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History and Theory of Psychology: An early 21st century student's perspective

Paul F. Ballantyne, Ph.D. 2008©.

Section 3:

Bridging The Gap: British Associationism, Psychophysics, and the Founding of a Discipline

The descriptive term "bridging the gap" refers to the monistic strivings of the transitional period to be covered in this Section (roughly 1749-1890s). With historical hindsight, this period can be viewed generally as a set of varied attempts to bridge the gap between previous 17-18th century philosophical inquiry into mentality and the rise of a late 19th century experimental-science of the mind. More particularly, however, each of the main investigative movements involved in this transition had their own specific contemporaneous concerns as follows:

British Associationistsreal and perceived world; simple and complex ideas
Psychophysicistsmeasurement of the mental-physical world relation
Wundt's Laboratory measurement of Sensory, Ideational, Affective elements
Wundt's Studentsmeasurement of higher mental processes

From the 1860s onward, Wilhelm Wundt (the eventual founder of so-called "physiological" laboratory psychology), would attempt to draw the associationist and psychophysical themes together. In doing so he produced the initial formulation of what would become the "discipline" of psychological science. There were, however, certain built-in constrictive limitations contained within Wundt's methodological assumptions and empirical methods (e.g., the goals, style, and intended content of his "experimental" practice), which even his own students would rebel against. In this regard, we should be careful to mention upfront that all of the philosophical and empirical inquiries to be covered in this Section (up to and including those of Wundt) take place within a pre-evolutionary intellectual context which later psychological science would have to surmount.

British Associationism

We have already encountered early appeals to associationist principles in the positions of Locke (1690) who mentions associations between ideas; as well as in Berkeley (1710) and Hume (1739; 1748) who emphasize associations between sensations. Further, with Kant (1781) we encountered a rationalist (rather than empiricist) form of associationism which he conceived as an interaction between sensation and a priori categories of the mind.

The subsequent figures who (in the mid-18th through early 19th century) further elaborated this implied association theory as an explicit psychology, were called "associationists." They were almost exclusively British (including David Hartley, Thomas Brown, James Mill, John Stuart Mill), and as a school are therefore referred to as the British associationists.

The British associationists will be concerned with bridging the gap between the real and perceived world which was the "tension of the time" left to it by Hume and Kant. These efforts, which took place in the definitively pre-evolutionary era (up to 1859), were based predominantly upon varied sorts of mechanical-atomistic thinking passed down from Hobbes and Newton. Further, all of the various permutations of British associationism ended up proposing one form or another of psycho-physical parallelism and we will want to become clear as to why this was so.

Under the earlier and informal philosophical forms of perceptual associationism, there was always an implied assumption of atomism. Berkeley and even Locke, for instance, had argued that we take all the sensory elements as presented, somehow combine these, and that is how one gains an appreciation of objects in the world. Although the various associationist figures covered below each produce their own particular account of how such associations come about and also put forward specific "psychological" theories regarding the relationship between so-called simple and complex ideas accordingly, the basic methodological assumptions of atomism remain largely unchanged throughout.

The British associationists claimed that association is a basic explanatory principle which can account for mentality, so we will want to consider the varied methodological starting-points, the methods of inquiry utilized, and the eventual endpoint of their particular positions in some detail. From a commonsense point of view, one can most certainly talk about associations between things as occurring in our daily life. One might read something in a book, or see something either on television or more directly during your daily routine, which reminds you of a whole lot of other things. Poetry, musical lyrics, and even instrumental mood music, for instance, all work on that premise. Similarly, commercial advertisements associate their products with concepts like happiness, success, and prestige. So, association of some sort certainly does occur on a daily basis. The main question at issue here, however, is whether association principles of the sort proposed by these figures will account for everything which is going on in the mind.

David Hartley (1705-1757)

The first of these figures is David Hartley (1705-1757), an English physician and philosopher who attempted to extend Newton's physics into a methodologically materialist psychology of association between ideas. His Observations on Man (Vol. 1 & 2, 1749) was a wide-ranging synthesis of the neurology, moral philosophy, and spirituality of the era.

Hartley's (1749) work is most notable to us for its advocacy of an explicitly stated psycho-physical parallelism. Being more of a Lockean than a Humean, Hartley granted the existence of physical objects. He was an indirect realist of the objective idealist stripe. Being also an atomist, however, he conceived of the physical world as a system of "vibrations," an idea he got from Newton and Galileo.

"My chief design in the following... is... to explain, establish, and apply the [twin] doctrines of vibrations and association. The first of these doctrines is taken from the hints concerning the performance of sensation and motion, which Sir Isaac Newton has given at the end of his Principia, and in the questions annexed to his Optics; the last, from what Mr. Locke, and the other ingenious persons since his time, have delivered concerning the influence of association over our opinions and affections... [including that] commonly referred to [as] the power of habit and custom..." (Hartley, 1749; Chap. 1, Introduction; In R.I. Watson, 1979).

These physical vibrations in the world, he suggested, caused sympathetic movements in the brain called "vibratiuncules". What is interesting about this theory is that both the worldly vibrations and the cranial "vibratiuncules" were considered as strictly physical phenomena, which ran in "parallel" with the sensations and ideas without directly causing them. Hartley considers them as the original material substrate for later mental activity.

Heidbreder (1933) indicates that Hartley's principle of mental association is a fairly standard and familiar one:

"The general law of [mental] association is that if sensations have often been experienced together, the corresponding ideas will tend to occur together; if A has been associated with B, C, and D in sensory experience, the sensory experience A, occurring alone, will tend to arouse the ideas of b, c, and d, which accompanied it. Association may be either successive or simultaneous. The former determines the course of thought, in time; the latter accounts for the formation of complex ideas" (Heidbreder, 1933, p. 54; emphasis added).

There were, thus, two "classes" of associational laws to account for: One for sensation making ideas (mental association); and the other for vibrations getting together to form "vibratiuncules" (physical association -a.k.a., the "doctrine of vibrations"). Both classes took place on the basis of contiguity and repetition but Hartley postulated a differential role for each in the production of "original automatic" versus subsequent forms of "voluntary" or "secondarily automatic actions of the body."

The key to understanding his adoption of this psycho-physical parallelism is to recognize that Hartley's goal is to distinguish between originally "automatic" action (later called bodily reflex) and the subsequent development of both learned "voluntary" action and what can be called second order automatic operations ("secondarily automatic actions of the body").

Utilizing the examples of both the development of speech (Prop. 21) and of walking (Prop. 77) in an infant, Hartley elaborates his scheme as follows:

"The newborn Child is not able to produce a Sound at all, unless the Muscles of the Trunk and Larynx be stimulated by the Impression of Pain on some Part of the Body. As the Child advances in Age.... an articulate Sound, or one approaching thereto, will sometimes be produced by this conjoint Action of the Muscles.... After they have recurred a sufficient Number of times, the Impression which these Sounds, articulate and inarticulate, make upon the Ear, will become an associated Circumstance (for the Child always hears himself speak, at the same time that he exerts the Action) [is] sufficient to produce a Repetition of them. And thus it is, that Children repeat the same Sounds over and over again.... So that the Child's articulate Sounds will be more and more frequent every Day -his inarticulate ones grow into Disuse.... Speech will also become a perfectly voluntary Action, i.e., the child will be able to utter any Word or Sentence proposed to him by others... (Hartley, 1749, Prop. 21, In S. Diamond, 1974).

"And thus... we are enabled to account for all the Motions of the human Body, upon Principles which, tho' they may be fictitious, are, at least, clear and intelligible. The Doctrine of Vibrations explains all the original automatic Motions, that of Association the voluntary and secondarily automatic ones...." (Hartley, 1749, Prop. 21, In S. Diamond, 1974).

"Walking passes into the secondarily automatic State more perfectly perhaps, than any other Action;... Now this Transition of Walking, from its voluntary to its secondarily automatic State, must be acknowledged by all to proceed merely from Association..." (Hartley, 1749; Prop. 77; In S. Diamond, 1974).

In addition to the "commonsense" approach of Locke and in severe contrast to the "logical" or "professorial" approaches of Hume and Kant respectively, Hartley brought with him the empirical observational skills of a physician. The result is a the first thoroughgoing application of materialist plus associationist principles to topics which border on the kind of developmental observations which would be carried out routinely in the following century.

Despite occasional discursive overstatements, Hartley is someone who has turned to the developmental aspects of the Lockean issue of simple and complex ideas. He attempts to use both material and mental concepts to understand their development. Further, there is a notable aspect of historical self-awareness in Hartley's writings because he recognizes that the particular analytical concepts he is using may very well prove "fictitious" in the long run.

Thomas Brown (1778-1820)

After Thomas Reid and Dugald Steward, Thomas Brown can be considered the third member of the Scottish Realist School of Common Sense. Having studied both law and medicine at the University of Edinburgh, Brown produced An Inquiry into the Relation of Cause and Effect (1804) and was appointed professor of Moral Philosophy there in 1810 but died of exhaustion by 1820. His chief work, Lectures on the Philosophy of the Human Mind was published posthumously that year (see also T. Dixon, (Ed.)., Life and Collected Works of Thomas Brown, 2003).

Brown, Stewart, and the Scottish School, attempted to counter the growing skepticism about reality and religion as generated by Hume. Brown’s ambivalent attitude towards the teachings of Reid and Stewart, however, is apparent throughout his Lectures (1820). That work is most notable to us for three things: A theory of "muscle sense" as providing both a means by which reality is know and a principle which unifies the mind; his choice of the term "suggestion" rather than association in order to emphasize the active selective aspects of mind; and his rejection of "nominalism" (later called the naming fallacy).

In his analysis of the processes of sensation, Brown attaches great importance to muscular sense as the basis for "objective reference" (Brown, 1820, Vol. 2, Lect. 25). Physiologists had recently begun to realize that tactile sensory impulses arise, not only from the outside world, but also from the interior of the trunk and limbs, and that these impulses are important in forming an understanding of the general attitude of our bodies as well as in the development of coordinated movements.

It was here that Brown provided a constructive critique of Thomas Reid's (1785) discursive distinction between sensation and perception. Reid had suggested a working distinction between sensation (being the simple "feeling" that immediately follows the action of an external object on any of our organs) and perception (being the "attribution" of this feeling to the external body as its cause) as follows:

"Thus, if it is asked, whether the smell be in the rose, or in the mind that feels it, the answer is obvious: That there are two different things signified by the smell of a rose; one of which is in the mind,... the other is truly and properly in the rose. The sensation which I feel is in my mind.... But this sensation... is occasioned by a certain quality in the rose.... All the names we have for smells, tastes, sounds, and for the various degrees of heat and cold, have a like ambiguity;.... they signify both a [felt] sensation, and a [attributed] quality perceived by means of that sensation" (Reid, 1785, Chap. 16; In Herrnstein & Boring, 1966).

Brown (1820) attempts to close the argumentative gap apparently left open in Reid's above account by way of emphasizing that it is not merely the smell but the "handling" of the rose (the muscular feedback it provides) which allows us to directly attribute the smell of the rose to a real object. In other words, in opposition to the skeptics, Brown held that our belief in the existence of reality was based on muscular activity -i.e., due to the sensations resulting from palpable manipulation of and bodily effort toward objects (Stagner, 1988). This, of course, is more of a corrective clarification rather than a counter-argument to Reid's direct realism which Thomas Brown shared.

A second important aspect of Brown's (1820) account is that he had specific and explicit theoretical differences with the traditional account of "association" provided by both Hartley (1749) and the older British empiricists. While not completely abandoning the term "association," he tended to favor the term "suggestion" to demarcate his departure from the former physiologically reductive and mental mechanistic aspects of those positions.

In enunciating his two principles of mental life -which he called "simple suggestion" and "relative" suggestion- Brown was attempting to remedy some of the main deficiencies of former association psychology. His was trying to make it more useful and self-consistent than it had formerly been.

Brown's primary ("simple") laws of suggestion are roughly equivalent to those proposed by "associationism" proper including contiguity, resemblance, and recency. He points out, however, that even these primary laws do not derive "solely" from either mental or bodily-animal sources (the argumentative weakness of Hume and Hartley respectively) but from both. In other words, he is striving for a monistic account of bodily constitution and intellectual aspects which was formally lacking.

Further, Brown's account of "relative suggestion" (the power to see relations among thoughts or objects) goes well beyond the bounds of former accounts because it attempts to show in detail why associations take a particular path (or course) in any given case. As Flugel & West (1964) put it in their account of Brown: "This ability to see relations has been a regular will-o'-the-wisp in modern psychology. It has constantly been lost to sight, forgotten or neglected, and as constantly rediscovered" (p. 21).

Brown's secondary laws of suggestion include: constitutional differences of mind or temperament; differing circumstances of the moment; state of health or efficiency of the body; and prior habits. They are explicitly intended to modify the primary (abstractly stated, decontexualized) laws according to the prevailing concrete conditions of existence and thereby explain why "at this particular time and place, the thought of 'cold' brought forth 'dark' rather than 'hot'; why the image of 'butterfly' sometimes produced 'bird' and other times 'moth'" (after Watson & Evans, 1991).

It is as follows that Brown abjures from both the mechanistic mentalism of the older empiricism as well as the potentially physiological reductive implications of Hartley's (1749) account:

"The primary laws are modified, not by constitutional and permanent differences only, but by differences which occur in the same individual, according to the varying emotion of the hour.... The temporary diversities of state, that give rise to varieties of suggestion are not mental only, but corporeal; and this difference of bodily state furnishes another secondary law.... How different are the trains of thought in health and in sickness, after a temperate meal and after a luxurious excess! It is not to the animal powers only, that the burthen [burden] of digestion may become oppressive, but to the intellectual also; and often to the intellectual powers even more than to the animal...." (Brown, 1820, Vol. 2, Lect. 37, original emphasis, In S. Diamond, 1974).

Various reviewers of Brown's early 19th century observational-philosophical approach to "suggestion" have either introduced or concluded their coverage by drawing analogies to later efforts along the empirical-associationist line. Thus one reviewer claims that: No psychologists actually tried to study these "laws" experimentally for about another century but when they did, the variables were very like those that Brown listed. Another that: Similar laws would be mobilized by associationistic psychologists (particularly the behaviorists) to account for the strength of conditioning. And likewise, another that: Contemporary laws, similar to those of Thomas Brown, are also found in the learning theory of Clark L. Hull, in his book, Principles of Behavior (1943).

We should be careful, however, to take note of the third important aspect of Brown's (1820) argument -i.e., the one concerning "nominalism" (later called the naming fallacy, or more specifically the psychologist's fallacy). Brown was so concerned with getting his terminology right that he took issue with Reid over even the most finite points of psychological subject matter. He complained, for instance, that Reid's account of consciousness was written out as if consciousness existed as something separate from the contents of the mind. Stagner (1988) summarizes this point quite nicely:

"Brown objected to the fallacy of 'nominalism,' in effect, the assumption that because a phenomenon has a name, it must have a separate identity. Specifically, he opposed the belief that 'consciousness' has some kind of existence independent of the contents of consciousness. Rather, consciousness is a name for a class of events: "there are not," he wrote, "sensation, thought, passions, and also consciousness, any more than there is quadruped or animal, as a separate being to be added to the wolves, tygers, elephants, and other living creatures" (1820/1970, p. 336). There is a recurring tendency in the history of psychology for writers to confuse the name of an object with its reality. The fact that there is a name for digestion does not mean that you can put digestion on a scale and weigh it. The same holds for perceiving, learning, desiring, and so on" (Stagner, A History of Psychological Theories, 1988, p. 71).

In other words, just as Brown was so very careful to differentiate his position from those of even his closest and intellectually amiable contemporaries, so we should likewise be doubly careful to note the divergence as well as the overlap between Brown's attempt at concrete description of "suggestion" and the later methodology of quantitatively defined "association variables" used in 20th century "learning" theories (see Section 5). The oft repeated, supposed analogy of approach may turn out to be wildly overgeneralized indeed.

James Mill (1773-1836)

Mill (the senior) was a Scottish born British philosopher, economist, historian, and progressive "Utilitarian" social theorist. Originally educated as a clergyman at Edinburgh, Mill gave up the ministry and went to London in 1802 to pursue a career writing for and editing periodicals. Under the influence of his friend Jeremy Benthem (who popularized the slogan "the greatest good for the greatest number"), Mill adopted Utilitarianism -which argues that political theory should be based upon a sound understanding of "human nature." This in turn led him toward a consideration of psychological matters in the associationist manner of the era.

Mill's main work on associationist epistemology, Analysis of the Phenomenon of the Human Mind (Vol. 1 & 2, 1829), advocated a form of mental mechanics which he called "mental physics." It was heavily influenced not only by Hobbes, Locke, Hume, and Hartley whose theory of association he applied and elaborated further; but also by the French Materialist writers.

The physics of the era was still very mechanistic and additive rather than truly dynamic or developmental. Although motion and change in the universe were now take to be an established and measurable fact, its fundamental material constituents (the elements) continued to be conceived of as essentially static entities. Let's recall here that the universal laws of mechanical motion (proposed by Newton back in 1686) dealt merely with what Aristotle once called "efficient" causation. They were descriptions of the effect or lack of an effect of some external material force on a given physical object. Right up to Mill's time, the undeniable motion of physical objects and the observable changes in not only heavenly but also organic (living) bodies was still taken to arise from merely external material-mechanical sources and any appeal to "final" causality -i.e., to the ends or directional outcome of a given dynamic event or developmental process- was still viewed as unscientific or even teleological (in the religious and mystical sense of that term).

Accordingly, Mill's "mental physics" account of human mentality retains a strict adherence to the kind of passive-mechanical atomism (a.k.a., reductive mental mechanics) which the medically trained Thomas Brown, for instance, had explicitly attempted to overcome. As Heidbreder wrote: "James Mill is sometimes cited as the associationist par excellence, for in his writings the associationistic principles were applied with such thoroughness and in such detail that their limitations became apparent along with their possibilities" (1933, p. 55). More specifically, the two main "limitations" of James Mill's (1829) account of mental physics can be considered as the necessary respective consequences of: (i) his return to the Lockean representationalist theory of perception; and (ii) his a reliance upon a strictly "additive principle" to account for the relationship between simple and complex ideas.

With regard to the first limitation, Mill's (1829) account of the "order" of associated ideas does not carry forward either Reid's (1785) or Brown's (1820) "direct realist" approach to perception, but instead relies upon a full-scale return to a Lockean (1690) indirect realist "copy" theory of perception outlined as follows:

"As ideas are not derived from objects, we should not expect their order to be derived from the order of objects; but as they are derived from sensations, we might by analogy expect, that they would derive their order from that of the sensations; and this to a great extent is the case.... Our ideas spring up, or exist, in the order in which the sensations existed, of which they are copies" (James Mill, 1829; Chap. 3; In Herrnstein & Boring, 1966).

As a consequence, the passive aspect of Locke's perception theory is carried forward into Mill's description of the origin of the strength of associations. As one reviewer declared: "Nothing is left of Brown's [active] secondary laws but frequency and vividness" (Diamond, 1974, p. 292).

"The causes of strength in association seem all to be resolvable into two; the vividness of the associated feelings; and the frequency of the association.... In general,.... the sensation is more vivid than the idea; or the primary, than the secondary feeling; though in dreams, and in delirium, ideas are mistaken for sensations...." (James Mill, 1829; Chap. 3, emphasis added).

"Next, we have to consider frequency or repetition; which is the most remarkable and important cause of the strength of our associations.... Learning to play on a musical instrument is [a] remarkable illustration of the effect of repetition.... as the repetition goes on, the sight of the note, or even the idea of the note, becomes associated with the place of the key or the string; and that of the key or the string with the proper finger. The association for a time is imperfect, but at last becomes so strong that it is performed with the greatest rapidity, without an effort, and almost without consciousness" (James Mill, 1829, Chap. 3).

Mill clearly viewed the mind as passive with the laws of frequency and vividness determining the formation of associations accordingly. Mill's violin or keyboard player (described above) reduces down to a mere mechanical receptacle or conduit for frequently repeated and vivid occurrences which 'happen to' rather than which are carried out by 'it.' This is surely a passive mechanism par excellence!

The human mind is portrayed here as a passive accrual of associations rather than an active creative function (as implied by Kant and -for different reasons- by Brown). If this be so, one might ask why so many music students give up their lessons or remain mere amateurs while so very few go on to become virtuosos? James Mill's passive account of association provides no answer to this question other than the rhetorically, self-evident, tautology that practice makes perfect!

With particular regard to the second limitation of Mill's account, he likewise portrays the ontological status of "simple versus complex ideas" as being merely additive. Gone is the roughly developmental transition from "original (simple) automatic-to-"voluntary" (complex)-to similarly complex "secondarily automatic actions" described by Hartley (1749). Instead, the assumedly higher order complex forms of thought are merely described as "coalesced, compounded or composed" additive concatenations of lower forms:

"Thus two complex ideas may be united together, by a strong association, and coalesce into one, in the same manner as two or more simple ideas coalesce into one. This union of the two complex ideas into one, Dr. Hartley has called a duplex idea. Two also of the duplex, or doubly compounded ideas, may unite into one; and these again into other compounds, without end.... [For example] Brick is one complex idea, mortar is another complex idea; these ideas, with ideas of position and quantity, compose my idea of a wall.... How many complex, or duplex ideas, are all united in the idea of furniture? How many more in the idea of merchandise? How many more in the idea called Every Thing?" (James Mill, 1829, Chap. 3).

To utilize the kind of apt, though counterfactual, analogy which formal logicians are so very fond of: If James Mill were a geologist, he would be implying here that all rocks on earth are either igneous or sedimentary (which are at best "conglomerate") but never metamorphic. The higher "duplexes" and "double duplexes" of Hartley [who actually called them "decomplex"] are portrayed by Mill as mere "conglomerates" of simple ideas -"without end" perhaps, but also without their own distinctive qualities.

To sum up, James Mill (1829) started out by sidestepping the direct realist account of Reid (1785) and adopted instead an explicitly indirect realist (representational) epistemology similar to that of Locke (1690). Like Hartley (and many others afterward), he also believed that the primary mode of operation of the human mind is association, but his account of the transition between simple and complex ideas falls far short of the mark intended by even Hartley's (1749) account. Similarly, in contradistinction to Brown (1820), Mill not only constricted the number of possible laws of association to two but also portrayed the process of transition between associations as passive rather than active. Some of the deficiencies of James Mill's account were overcome, however, by his son John Stuart Mill who (albeit briefly) put forward a relatively progressive distinction between mental physics and "mental chemistry."

John Stuart Mill (1806-1873)

Mill (the younger) was a social theorist, British philosopher and liberal member of Parliament from 1865 to 1868. As the son of James Mill, he was initially educated along the lines of his father's mechanical approach to associationism. John, however, suffered a nervous breakdown at age 20 which he attributed directly to his rigid education (J.S. Mill, Autobiography, 1873). He subsequently sought to emancipated himself both personally and intellectually from this influence.

His best known political work is On Liberty (1859). It argues for personal freedom because such freedom allows creative individuals to better contribute to society. Mill also suggests that since free-market capitalism tends to result in inequity and poverty, society would be better served by adopting some form of liberal socialism.

His most important work as far as psychology and science are concerned is A System of Logic (1843, up to its 8th edition in 1874). Here, Mill drew upon a direct analogy to the burgeoning discipline of chemistry to argue that mind plays an active-creative role in the formation of simple ideas; and that "complex ideas" are more than the sum of their parts because they contain properties not found in simple ideas. He emphasized his departure from his father's mechanistic mental physics by calling his approach "mental chemistry."

At this time, the discipline of chemistry was shifting away from the mere "systematic art" of classifying elements (described by Kant, 1781) toward consideration of active-creative events like chemical reactions. It was becoming clear that in the case of chemical reactions, things did not simply "add up." If you consider all the properties of hydrogen (on its own) and all the properties of oxygen (on its own), you are in no position to know about the peculiar properties of water per se. The same can be said of the reaction between sodium and chlorine to make ordinary table salt. Such chemical reactions were beginning to be recognized as creative and also directional processes. When they occur, either in nature or in the laboratory, things happen which can't be predicted by mere insular reference to the properties of the original elements. The new properties of compounds (water, salt) can not be explained away as simply the additive sum of the original properties of their elements. A chemical reaction is a metamorphic, transformative, and directional event resulting in new properties in the compound.

Having noted these advances, J.S. Mill (1843) draws a pointedly direct analogy to them while contrasting the additive, mechanical and static associationism of the past with his more active and creative mental chemistry approach. To paraphrase the extract presented below: Just as in the case of chemical reactions, something appears in the formation of "complex ideas" that is not present in the simple ideas taken "separately." Complex ideas, therefore, are not merely additive compositions of simple ideas. They may be said to "result from," or be "generated by" the simple ideas, but they do not "consist of them."

"It is obvious that complex laws of thought and feeling not only may, but must, be generated from these simple laws [of association]. And it is to be remarked, that the case is not always one of Composition of Causes: the effect of concurring causes is not always precisely the sum of the effects of those causes when separate, nor even always an effect of the same kind with them.... [The] laws of the phenomena of mind are sometimes analogous to mechanical, but sometimes also to chemical laws. When impressions have been so often experienced in conjunction, that each of them calls up readily and instantaneously the ideas of the whole group, those ideas sometimes melt and coalesce into on another, and appear not several ideas, but one; in the same manner as, when the seven prismatic colors are presented to the eye in rapid succession, the sensation produced is that of white. But as in this last case it is correct to say that the seven colors when they rapidly follow one another generate white, but not that they are white; so it appears to me that the Complex Idea, formed by the blending together of several simpler ones, should,... be said to result from, or be generated by, the simple ideas, not to consist of them.... These, therefore, are cases of mental chemistry; in which it is proper to say that the simple ideas generate, rather than that they compose, the complex ones" (J.S. Mill, 1843, Vol. 2, Bk. 6, Chap. 4; emphasis added).

This was the first high-profile and influential step away from the former mechanistic model of associationism so it is worth dwelling on for a moment. In particular, we should note that Mill's (1843) argument contains two aspects which have been differentially taken up in subsequent history of psychology.

The first aspect, regarding part-whole relations, is the least exciting. Complex ideas are not simple additive "conglomerations" but are the products of some kind of interaction between the simple ideas which participated in their formation. The simple ideas are lost or no longer attended to in the eventual product. It was this part-whole aspect of Mill's (1843) argument that would be taken up by subsequent thinkers and mentioned in most subdisciplinary history books. E.G. Boring's (1942) account of J.S. Mill, for instance, runs as follows:

"The whole is less, as well as more, than the sum of its parts. John Stuart Mill had corrected his father on this point. Ideas, he had noted, combine in a kind of mental chemistry, for the parts are lost in the compound which also has properties that were not contained in the parts" (Boring, Sensation and Perception in the History of Experimental Psychology, 1942, p. 9; emphasis added).

There is, however, a second, more exciting though implicit aspect contained in Mill's (1843) use of the term "generated" which should also be highlighted and drawn into our understanding of the proper methodology or methods to be used in psychology. The formation of complex ideas from simple ones is a dynamic, transformative and directional (rather than merely a passive mechanical or interactive) process which contains its own internal motion. The simple ideas are not static constituents of the mind which are forced into motion by some external event, but are rather active participants in the generation of a complex idea. This aspect of the argument, while sometimes recognized by later historical accounts was not actually put into practice during the contemporaneous psychophysical or subsequent disciplinary-building eras of psychological inquiry and we should be careful to emphasize why this was so.

Briefly stated, part of the blame lies on Mill's own doorstep. There was an unsettling and regrettable disparity between his initial use of the active (part-whole, generative) mental chemistry analogy to account for the ontological aspects of "complex ideas" (1843) and his own subsequent more epistemological "theory of the object" presented some twenty-two years later (1865). So let's consider this argumentative disparity.

In his Examination of Sir William Hamilton's Philosophy (1865), Mill took up the issue of formulating a "psychological" theory regarding our belief in the external world:

"I see a piece of white paper on the table. I go into another room.... But, though I have ceased to see it, I am persuaded that the paper is still there. I no longer have the sensations which it gave me; but I believe that when I again place myself in the circumstances in which I had those sensations, that is, when I go again into the room, I shall again have them.... The conception I form of the world existing at any moment, comprises, along with the sensations I am feeling, a countless variety of possibilities of sensation.... These various possibilities are the important thing to me in the world. My present sensations are generally of little importance, and moreover are fugitive: the possibilities, on the contrary, are permanent, which is the character that mainly distinguishes our idea of Substance or Matter from our notion of sensation" (J.S. Mill, 1865, Chap. 11; emphasis added).

In this latter epistemological account, Mills seems to be attempting to maintain an active representationist view consistent with his earlier ontological approach and along the lines of Locke's theory of "reflection." But the static aspect of the new account can be appreciated when we recognize that in his effort to to explain how we maintain a previously "sensed" object in our consciousness, Mill (like Hume regarding "self") is seeking out something which "persists." Mill found this persistence in the "permanent" possibilities for sensation. Boring (1950) views this latter position as "modern" but he is completely wrong on that count. Mill's theory is surely a return to the ultimately phenomenalist search for an extra principle to account for the regularity of "fugitive" sensations. In this case the extra principle is not God (as in Berkeley), but the "permanent" possibility of revisiting or of expecting to experience a given set of sensations.

So, in the intervening years between his two accounts, Mill went from utilizing an initially tidy and concrete ontological analogy which emphasized the inherent activeness and albeit indirectly perceived correspondence between objects and ideas (1843), to a rather messy and abstract epistemological discussion of the "distinction" between ideas of "matter" (as "possibility of sensations") and the having of "sensations" (1865). We can look back and wonder how very much easier it would have been for Mill to have simply foregone that abstractness by adopting a direct realist account (along the lines of Reid or Brown), but that particular possibility appears to have escaped Mill altogether.

The typical historiographic procedure for dealing with this divergence between Mill's two accounts has been to pay cursory lip-service to the whole-part aspect of Mill's (1843) argument (regarding the irreducibility of the whole), -e.g., by suggesting that it was the source of Wundt's portrayal of perception "as a complex or an integration" (Boring, 1950, p. 231)- and to then acquiesce to Mill's (1865) sensationist position by advocating the use of methods which reduce the active whole down to static sensory parts anyway. Thus, instead of repudiating this later position, Boring embraces it and likens it to a forerunner of Titchener's (1909) highly elementist "context" theory in which "a potential [perceptual] context is... nothing else than a possibility of sensation or image" (p. 233). What Boring is implying here is that even though the "whole" (the "perceptual" products of the interaction between sensory or image elements) and the active aspects of perceptual processes are what we really want to understand, the de facto task of sensation psychology is to systematically rediscover and measure the relatively elementary parts in the hope of eventually putting Humpty Dumpty back together again. But as anyone who has heard the old nursery rhyme knows, this is an impossible task even for all the king's horses and all the king's men!

As outlined immediately below, the nearly hegemonic status of this supposed necessity to use element-seeking procedural methods in psychology has very deep roots going right back to the predisciplinary sensory research of Helmholtz. There are also origins in the manner in which Wundt considered J.S. Mill's (part-whole, generative) argument to apply to the circumscribed confines of his own "physiological" experimental psychology. It bears mentioning here too that Wundt was teacher to Titchener, who in turn was mentor to the young E.G. Boring in this respect. For these and other reasons, early 20th century sensation psychologists such as S.S. Stevens -who as we will see in Section 5 was influence by and exerted influence on Boring- routinely tore asunder that which was initially claimed to be the subject matter under of investigation, "active" human perception and thinking.

Müller's Vitalism, Fechner's Psychophysics, and Helmholtz on sensory elements

We now turn to a heterogeneous group of three scientific figures who are located precisely in the formative mid-through-late 19th century disciplinary gap between philosophy of mind and the established science of psychology. They were predominantly German, Continental, figures who while sensitive to the philosophical gap left to them by Kant and Hume, were also scientists seeking a scientific-empirical solution to the issues they considered as most pressing. For Johannes Müller this meant focusing on the active (a.k.a., "vital") organism, for Gustav Fechner it was "psycho-physical" relations, and for Hermann Helmholtz it was a search for the "elements" of sensation.

In this era of research, the former predominantly epistemological debates (between Hume, Berkeley, and Kant through to the two Mills) were informally bracketed (shelved if you will) in favor of more empirical or procedural concerns. The primary intellectual effort of these figures was directed toward how to carry out empirical research into the mental-physical world relation, and they un-apologetically utilize the methods of physiology, mathematics, and the physical sciences to investigate questions regarding life-processes; organizational or active aspects of the perceptual apparatus; and its material basis accordingly.

We can look back upon the collective works of these three figures and observe that their methodological decisions (their weighing of one assumption versus another) were guided more considerably by the question of how to conduct physiological or psycho-physical research rather than by the former philosophical (ontological or epistemological) concerns of their intellectual predecessors. The main strength of their work is that they each (to varying degrees) take up one or another aspect of new advancements in early 19th century science. Their shared limitation is that they are all proposing, either temporally or intellectually speaking, pre-evolutionary approaches to the empirical investigation of mentality. Further, the respective strengths and weaknesses of their work became the very starting point for Wundt's initial methodological propositions regarding the scope and methods of his laboratory based "physiological" psychology, so we will want to review the relevant details in that regard.

Johannes Müller (1801-1858)

Müller was a German experimental physiologist. As the first "Professor of Physiology" at the University of Berlin, he not only carried out laboratory research but also attempted to draw together the empirical and theoretical advances made in the life sciences to date. His major work Handbuch der Physiologie des Menschen [Handbook of Physiology of Humans] (Vol. 1 & 2, 1834–40), was translated as Elements of Physiology (1843).

The particularities of that work include: Müller's "Vitalism" (a pre-evolutionary anti-reductive corrective to the new rise of mechanistic assumptions); its elaboration on the "Doctrine of the Specific energies of Nerves" (originally proposed by him in 1826); and its representationalism which acted as an unfortunate foil to his otherwise progressive physiological account.

With regard to understanding Müller's advocacy of vitalism (a life force which accompanies the material aspects of physiology) we should note the "empirical and theoretical" aspects of the pre-evolutionary intellectual context in which it was proposed.

First of all, the "empirical" (observational-experimental) aspects of physiological research had been accruing steadily since the time of Descartes (1662) and the later French materialists (La Mettrie, 1748; Cabanis, 1795). As indicated in the above "Chronology of Reflex Action" (from Fearing, 1964), Müller was one among many 18th-19th century figures to have tackled the issue of mechanical versus human existence. Between Descartes and Hartley, for instance, 18 figures are listed; with 20 more up to Müller; and a further 17 up to the time of Wundt.

Secondly, physiological "theory" regarding the active organism had also progressed, but only somewhat. By Müller's time, for instance, it was considered rather passé to attempt to avoid reductive mechanism (of the Hobbesian sort) by way of appeal to "the immaterial soul" as in Descartes' interactive dualism. Similarly, although it was still acceptable to adopt either the seemingly contradictory "self-winding machines" argument of La Mettrie (1748); or even the explicitly agnostic "psycho-physical parallelism" argument (a la Hartley, 1749) -for each would allow empirical research to continue- it seemed far easier to many of the younger early 19th century researchers to just assume a "materialist" harmony and reciprocal organization of parts stance (after the manner of J.C. Reil, 1795). This situation, however, was bothersome to Müller's systematic mind and he set out on various occasions to advocate the virtues of a "vitalist" alternative.

Müller recognized that contemporary empirical advances in the biological and physiological sciences were bumping up against the boundaries of typical mechanistic-materialist theoretical doctrines regarding the primary questions of life: "What distinguishes a living organism?" "How does the mentality of animals differ from that of human beings?" "How do higher voluntary actions differ from lower reflexive ones?" Simply shelving the metaphysical aspects of these inquiries in favor of carrying out research would not, in the long run, be the best course for the new discipline of "physiology" to take because these larger issues guide the structure of (and conclusions drawn from) that research.

More specifically, Müller's, motive for his 1830s-40s appeals to some -as yet unexplained- "vital" principle was that he recognized the nervous system was in some respect prepared to meet the world. Human beings are not simply lumps of inert matter waiting for something to come along and physically shove them into motion, nor are they machines which require energy to be injected from an external source, but are "active living substance." Similarly, the perceptual apparatus used during such active life processes is itself not simply a "passive receptacle" but has its own special properties which physiology should set out to study and explain.

The point of his vitalism is that the passive mechanistic view of the living human being, and animals for that matter, was becoming increasingly inadequate in the light of what was already known about living organisms. The organization of the brain and nervous system in whole and in part had to be put there somehow and for Müller, it was the appeal to a "vital principle" which fulfilled this role albeit inadequately. Reil's (1795) strictly materialist account had also recognized the importance of observing "organizational relations between parts" but had remained mute as to the origin or importance of that organization for understanding the activeness of the whole organisms under study. So, having started out as a good Kantian, Müller rejects Reil's somewhat emergent materialist position.

To the modern post-evolutionary reader, Müller's (1843) appeal to vitalism reminds us of Anaxagoras (his principle of "nous" as a special substance that is present only in living beings). When we haven't got any other explanation of how something got there, we can always draw upon some abstract principle like 'nous,' or in this case, the 'vital' principle. It is important to note, however, that Müller's principle of vitalism was stated prior to Darwin's (1859) Origin of Species. After 1859, this kind of solution would be both unnecessary and untenable. Müller's, as it happens, was almost the last major call for a vitalistic principle. After 1859 the solution became obvious to all concerned that how this kind of organization got there was through some kind of selective evolutionary process. Only then did it became possible to account for such active life processes in an emergent materialist (rather than a mechanistic materialist) manner.

It was not at all uncommon for the senior physiological researchers of Müller's time to insist upon a "vital principle" because they could not see how such organization, which they were beginning to understand quite well, could have come about otherwise. After 1859 this sort of idea would not occur again because -whether they understood the theoretical details or not- the newer generation of practicing physiological scientists recognized that (with a general concept of evolution) we could conceivably account for how the organization got there and therefore account for life itself without any need for an extra appeal to something non-material.

The next major point regarding Müller's (1834-40) account, is to understand how his adoption of representationalism undermined the potential explanatory impact of his major life contribution to physiology "the Doctrine of the Specific energy of nerves." What we have in Müller is a correct account of what nerves do, which is embedded within an incorrect and counterproductive indirect theory of perception.

Against the older (mystical-theological) "incorporeal copy" theory of the nerves (a la Descartes, 1662) -which portrays them as passive, indiscriminate conduits through which immaterial copies (a.k.a., images) of objects pass into the soul,- Müller proposed a relatively more ontologically materialist, active, and selective alternative. This specific energy of nerves doctrine (as he called it) states simply that: Stimulation of a given nerve produces only one form of sensation regardless of how it is stimulated. Under conditions of natural (everyday) stimulation, each of the five sensory modalities is "specific" in that each is responsive to its own kind of stimulation. Further, under the exceptional conditions of illness, injury, or artificial electrical stimulation the resulting experience is specific to the nerve which is stimulated.

We should note here that Müller's role in proposing and elaborating the doctrine (1826 and 1843 respectively) was one of drawing together the results of a long chain of basic neurological observations under a single label. The examples he uses reflect the empirical gains and past efforts of many other figures. With regard to the optic nerve: electrical stimulation; pressing the eyes mechanically in the dark; and blows to the head all stimulate experience of light. Likewise, the auditory nerve will conduct only one kind of energy (sound energy) and it doesn't matter how it is stimulated that's what is produced. Humming of the ears, for instance, is produced when the ear becomes infected as well as under conditions of electrical stimulation to the auditory nerve in the laboratory. In other words, Müller's doctrine argues that "copies of objects" per se do not enter (passively or otherwise) into the mind, but rather that the nerves provide us with specific "information" about the world around us in an active and rather selective manner.

These are the fundamentally correct aspects of his "selective irritability" doctrine regarding the nerves. The actual discursive manner in which the doctrine was stated, however, was highly problematic. In short, the potential emergent materialist implications of the doctrine are completely undermined by Müller's adoption of an indirect theory of perception so we will have to cover the details of his epistemological account (as well as their immediate disciplinary aftermath) before elaborating those implications.

Müller was a representationalist but he wasn't alone in adopting this position. We don't, in fact, find anyone overcoming this aspect of his work for some time to come; even Darwin doesn't do that. More immediately, this indirect theory is a common theoretical problem for all three of the main transitional 19th century figures we are currently considering (Müller, Fechner, and Helmholtz). Being representationalists they are unable to bridge that gap between the thing-as-known and the thing-in-itself. But from a scientific psychological point of view bridging this gap is quite important. All three of these figures intuit that the gap is both bridged in actual life and thus potentially bridgeable in theory. The old "being versus discourse" dialectic was recognized but despite their successive efforts to do so, none of them found the way. Understanding the details of Müller vs. Fechner, vs. Helmholtz in this respect will therefore be highly instructive.

With regard to Müller's particular approach to perception what interests us most is that although the three functional stages he postulates are an active version of Locke's methodologically materialist (outside inward) account, the crucial structural aspect (the assumed a priori status of the nervous system) is rather Kantian because it is through the nerves that the mind is prepared to meet the world as it were.

First of all with regard to the functional aspects, Müller portrayed perception as a physiological version of Locke's three stage theory. The names for his three stages (as depicted below) are identified a little differently but their general functional relationship (from outside inward) conforms to that of Locke:

The Lockean-like (outer to inner) function of Müller's three stages theory of perception: 1= External nature; 2 = Senses (including the specific energy of "material" nerves); 3 =the Sensorium (which is conceived of as an active perceiving mind or brain).

Secondly, however, we have already seen (in Section 2) that the old Lockean empiricism does not stand up very well on its own. This was what Berkeley and particularly Hume had pointed out to us. Kant then came along to "save empirical science" from skepticism by postulating rational "categories" of understanding because without some sort of fundamental reciprocity between mind and world we can not account for the order and necessity of our experience. Kant, therefore, attempted to account for such order by showing how perceptual order is impressed upon worldly experience by the a priori categories of understanding.

For Kant such order and necessity comes from inside the mind. Similarly, Müller's account of the structural aspects of perception, fit right in here with the Kantian view because his order and necessity are also going to come from inside: They are going to be "given" by the nerves. From a structural perspective, then, Müller's doctrine of specific energy of nerves will be a physiological or anatomical equivalent of the sort of thing that Kant was taking about. As R.I. Watson (1979) pointed out: "Müller saw his doctrine as supporting the nativistic views of Kant about that which we perceive. After all, what is more innate than the nervous system itself?" (p. 104).

Without the aid of evolutionary theory to back him up, Müller ran into considerable difficulties while walking the fine line between Lockean and Kantian accounts. Note, for instance, that according to the above diagram the nerves are portrayed as material "intermediaries" between perceived objects and the mind (Sensorium). Further, according to Müller, it is this very "materiality" of the nerves which guarantees the functional reciprocity between the "Sensorium" and external material nature. This is the strongest aspect of Müller's epistemological position and the modern reader might be tempted to assume therefore that he would simply adopt an explicit direct realism (along the lines of Reid or Brown); but not so in the case of Müller!

Unfortunately, his actual epistemological account of what is immediately perceived does not name objects but rather the "conditions of the nerves." Through Müller's embedding of the specific energy of nerves inside an indirect realist account, he initially asserts what can be read as a typically representationalist conclusion; the denial of direct contact with "external bodies" as follows:

"Sensation consists in the sensorium receiving through the medium of the nerves, and as the result of the action of an external cause, a knowledge of certain qualities or conditions, not of external bodies, but of the nerves of sense themselves; and these qualities of the nerves of sense are in all different, the nerve of each sense having its own peculiar quality or energy" (Müller, Elements of Physiology, 1843; Vol. 2, Bk. 5, Pt. V; emphasis added).

According to him, what we are "immediately" perceiving is not the world per se but "certain qualities or conditions" of our nerves. Well, Socrates said, "Know thyself," but he didn't know that he was talking about the nerves!

Müller, however, later clarifies this seemingly solipsistic basic position and attempts to reassert our contact with the world by way of calling attention to the "materiality" of the nerves:

"The immediate objects of the perception of our senses are merely particular states induced in the nerves, and felt as sensations either by the nerves themselves or by the sensorium, but inasmuch as the nerves of the senses are material bodies, and therefore participate in the properties of matter generally occupying space, being susceptible of vibratory motion, and capable of being changed chemically as well as by the action of heat and electricity, they make known to the sensorium [or brain], by virtue of the changes thus produced in them by external causes, not merely their own condition, but also properties and changes of condition of external bodies. The information thus obtained by the senses concerning external nature, varies in each sense, having a relation to the qualities or energies of the nerve" (Müller, Elements of Physiology, 1843; Vol. 2, Bk. 5, Pt. VIII; emphasis added).

Müller's argument is that because the nervous system itself is "material," it provides us with a way of contacting the matter 'out there.' In his terms, the nerves are giving us "information" about "external bodies." Again, there is an element of truth to Müller's appeal to the materiality of nerves as guaranteeing reciprocity between the perceiver and the world, which I don't think anyone (especially Müller) would wish to deny. That is, when we come into the world, we are born with a particular kind of nervous system that does prepare us to receive the world in a particular way.

The question at issue, however, is whether such a nervous system allows us to perceive the world per se or simply allows us to construct the world in our own heads. By adopting an indirect realist position to epistemology, Müller was initially forced into discursive language which implies the latter position. Müller's theory of perception is Kantian in that we only have direct access to the phenomena of the nerves. It is also as indirect as that of Locke's appeal to "experience", or Hume's appeal to "sensual image plus habit", and therefore runs into the same logical reductio.

In the final analysis, Müller becomes rather desperate to make that connection to the world, because he knows that if there is no such connection, the whole science of physiology goes out the window. Being couched within representationalism, however, his argument is circular, self-contradictory and dogmatic. If we adhere strictly to the logic of his epistemology all we can really know is the particularities of Müller's own nerves. So his adoption of an indirect realism augmented by an appeal to the materiality of the nerves doesn't work. It is still left with the tension between the real and perceived world handed down to physiology by Hume and Kant.

Müller doesn't solve the problem of knowledge but at least he made an attempt. Müller's particular contributions to later disciplinary developments include his anti-mechanistic position regarding physiology; his account of the selective irritability of the nerves; and his day to day professorial role in teaching laboratory skills to a new generation of researchers (such as Th. Schwann, R. Virchow, Helmholtz, and Emil DuBois-Raymond) who would in turn became notable founding figures in "neuropsychology."

Finally, it should be noted that although Müller seems to have implicitly favored the nerves as the "seat" of the selectivity of sensation, he was also careful enough to defer explicit judgment on that issue for it would have gone beyond the available contemporary evidence. Subsequent modern research would show that it is not the properties of the nerves themselves per se but rather their normal functional relationship with the particular brain centers at which they terminate that is the decisive source of their specificity. In other words, peripheral and central nerves can now be transplanted in lower animals and they function relatively normally in their new location.

To sum up our coverage of Müller: While his twin doctrines of vitalism and the specific energy of nerves did much to focus the research interests of most physiologists on an active organism; his adoption of an indirect realist theory of perception did much to focus others' attention away from appeal to objects and toward the mathematical measurement of so-called psycho-physical (Weber-Fechner) or sensory (Helmholtz) elements. Notice that the problem which Kant had drawn our attention to was the problem of sensation. Müller tried to provide an approach which would bridge the gap between the organism and the world but failed.

In the aftermath of Müller, Fechner's "psycho-physics" will make a similar attempt, while Helmholtz (in contradistinction to both attempts) believed more modestly that if we could just find a way to measure sensation better, perhaps these metaphysical issues would work themselves out eventually. But before moving on to Helmholtz, we should first give some account of the advancement of so-called psychophysics by mentioning the positions of Weber and Fechner.

Ernst Weber (1795-1878)

Born in Wittemburg, Germany, the third of 13 children, Weber received his doctorate in physiology from the University of Leipzig in 1815. He began teaching there immediately after graduation and continued until retiring in 1871.

Weber was a fairly inauspicious gentleman who began his career by carrying out basic physiological research measuring the smallest "noticeable distance" between two points for touch sensation on various parts of the body. Later, however, he carried out research regarding the somewhat more complicated issue of "sense discriminations" (judgments) of weight; successively presented line lengths; and illumination. While these findings were all reported by him in a Latin language booklet (1834), it was not until his Handworterbuck der Physiologie [Handbook of Physiology] (1846) that they attracted much attention. Further, Weber's main importance for us is that the more complicated aspects of his research helped set the stage for Gustuv Fechner (1860) to officially launch the new field of "psycho-physics."

Regarding the simplest aspects of his cutaneous (skin) sensation research, Weber used the dulled points of a standard compass to find that the "two-point threshold" on the skin varied with the body part investigated. The threshold for the tip of the tongue (1 mm), for instance, was found to be more than fifty times as precise as that of the upper arm or thigh; and similarly, that the back had the largest two-point threshold (60 mm). Later, he explained these results by suggesting that the skin is divided into areas ("sensory circles") with the respective sensitivity of any specific area corresponding directly to the relative distribution of the nerve endings in that area (1852).

Regarding the more complicated, seminal, aspects of his research, Weber (1834) also reported carrying out "just noticeable differences" (JND) research for judgments of weights under two conditions. In the first condition, weights passively rested on the hand of a subject. In the second condition, the weights were actively handled by the subject. Two important discoveries were forthcoming: (1) that active perception is finer than passive perception; and (2) that the JND in both conditions was always a "constant fraction" of the basic noticeable increment of weight involved.

To elaborate on the first discovery, Weber wanted to know "how much heavier" does the second weight have to be before it is judged to be different from the first. Under the condition of passive judgments, where the weight is simply placed on the subject's hand, the difference has to be fairly large (1 part in 30). But under conditions of active discrimination, where the weights are picked up by the subject, the required difference is considerably smaller (1 part in 40). We gain more discriminating information from our active perceptual activity. This was the first empirically measured indication that such active perceptual discrimination is important.

To elaborate on the second discovery, each subsequent detectable increase in weight sensation occurs only when the basic incremental difference for that modality has been surpassed. Double the weight, double the required increment of increase in weight; half the weight, halve the required increment. For instance, in the second active condition of weight discrimination, if you are holding a 40 pound weight in one hand, you will be able to recognize that a 41 pound weight in the other hand is in fact different by hefting it upward. But if the first weight is 20 pounds, you could detect a mere half pound difference. In other words, with regard to active weight discriminations, we can recognize a 1/40 difference, whatever the particular weights involved are. Weber's point was that the same relative "ratio" is "constant" across comparisons of the same kind.

Further, Weber presented empirical evidence that this observational regularity was not just peculiar to weight judgments but also generalized to visual judgments regarding lines presented successively; as well to judgments of luminosity; and he further stipulated that it might also apply to other senses like sound too.

"I have shown... that one can still perceive a difference between two lines when one is 100 millimeters long and the other 101, so that the difference is 1/100 of the length of the constant line, but that the lines seem to be equal if the difference is still less, e.g. when one line is 100 millimeters and the other 100.5. Under these circumstances one does not perceive the .5 millimeter by which one line is longer than the other. But under other circumstances, e.g., if one line is 4 millimeters long and the other 4.5, one perceives the difference of .5 millimeter very clearly. From this we see that with lengths, just as with weights, we perceive in comparison not the absolute but the relative difference -a fact which can also be confirmed in hearing, and from which one can draw a number of conclusions as to how we go about comparing two magnitudes by means of our senses...." (Weber, 1835, In Diamond, 1974; emphasis added).

Weber (1835) suggests the perceived difference between the two experimentally presented sensory stimuli is dependent not upon the "absolute" size of the difference but upon the "relative" ratio of difference of the "constant standard" for that particular sensory modality (e.g., 1/40 for active weight discriminations; 1/10 for illumination, and 1/100 for visual line judgments).

This empirical regularity was later labeled by Fechner (1860) as "Weber’s law" or the Weber "fraction" and was given a formal generalized mathematical expression as follows: dR /R = k, which means simply that the proportion of the minimum detectable change (dR) to the strength (size) of the stimulus (R) is a constant (k) across varying levels of intensity (with R standing for "Reiz" in German, meaning stimulus). What is constant is the ratio between the basic stimulus size (e.g., weight, line length, or luminosity) and the extra amount required to bring a discrimination of change about.

In anticipating later refinements, we should mention here that although this "constant" ratio holds true for a wide range of medium intensities it was eventually found to break down for very low and for very high intensities. So, today's psychophysicists have much more complicated formulas to account for these extreme conditions.

Even though Weber considered his observational generalization as important as any other empirical physiological regularity, he did not consider it as having any far reaching philosophical significance. Gustav Fechner, however, places it in the very center of a new psychological movement:

"To Fechner, its significance lay in the fact that it revealed a connection between the physical and the psychical -an exact mathematical relationship- and a connection of some sort between the two worlds was what Fechner had been seeking for long, anxious years with all the terrible earnestness of his unity-loving nature" (Heidbreder, 1933, p. 79).

Gustav Fechner (1801-1887)

After receiving an MD in 1822 at the University of Leipzig, where Weber had been teaching physiology since 1815, young Fechner initially failed to receive any official position in physiology and made ends meet by translating various physics textbooks (from French to German). This, in turn, led to a teaching position in physics at Leipzig from 1824-1839. At that point, however, he fell into 11 years of depression until October of 1850 when he believed he had found a "psycho-physical" basis for a spiritualist philosophy of science.

During this middle depressive period, in which he was wrestling with the problem which Kant had left us (the supposed disconnect between the perceiver and the world), Fechner was initially influenced by Schelling who considered philosophy as the science of the absolute in its double manifestation: nature and mind. Fechner was then rather profoundly influenced by Weber's (1846) modest summary of his basically empirical work -especially the mathematical constant which Fechner now labeled "Weber's Law."

Fechner suggested that the true significance of this empirical law lay not in its mere empirical-descriptive aspects but in the methodological realm. For according to him, it revealed a long sought after connection between the physical and the psychical. Fechner's Elements of Psychophysics (1860) was the culminative summary of his own work during this period, and while it did not immediately (or even ultimately) "turn the world's ear" toward his philosophical view, it did spur others including Helmholtz, Volkmann, and then S.S. Stevens onto their elaborations of psychophysical measurement.

Fechner's major preoccupation during his personal depressive phase was with finding a way to establish a relationship between the seemingly separate physical-scientific and the spiritual-ethical world views. Here he was influenced by Schelling (1775-1854) who, like Fichte, was part of that whole turn of events in philosophy which followed from Kant's supposedly unresolvable antinomies. Schelling and Fichte rejected Kant's convenient appeal to merely logical antinomies and pointed out that in "practical" terms all philosophers and scientists are required to abide by the "theoretical imperative" -they must take a stand on controversial issues instead of just living with them as ultimately unresolvable quandaries. In considering this post-Kantian period of philosophy Ilyenkov (1977) encapsulates it into what he calls the "monistic strivings" of the times. This was a period in which figures like Schelling and Fichte are attempting to work out a "unitary conception" of the world which overcomes the logical quandaries of the past:

"That is the point that divided Fichte and Schelling from Kant; the intellectual culture of humanity cannot lie eternally like Buridan’s ass between two equally logical systems of ideas about the most important things in life. Mankind has, in practice, to act, to live; but it is impossible to act simultaneously in accordance with two opposing systems of recommendations. We are forced to choose one of them and then to act strictly in the spirit of its principles.

Kant himself, it is true, demonstrated in his last works that the arguments of practical reason must all the same tip the scales in favor of one system or the other, although on a purely theoretical plane they are absolutely equal. But with him this theme only broke through as one of the trends of his thinking, while Fichte and Schelling transformed it into the starting point of all their meditations. Hence the slogan about victory, too, in the theoretical sphere. One of the clashing logical conceptions must still prevail over the other, its opposite, and for that it must be reinforced by arguments no longer of a purely logical, rather purely scholastic quality, but armed with practical (moral and aesthetic) advantages as well. Then it was assured of victory, and not simply of the right and the chance of waging an eternal academic dispute" (Ilyenkov, Dialectical Logic, Essays on its History and Theory, 1977, Chap. 4, Pt. II; emphasis added).

With regard to how these "monistic strivings" were picked up by Fechner as a basis for scientific psychophysical investigations, we can not do better than to turn directly to Edna Heidbreder's masterful account:

"But if psychology is looking for a picturesque ancestor, it can hardly make a happier choice than Fechner, a simple, subtle, profoundly learned man, in the grip of an irresistible impulse to take ideas seriously, and utterly at the mercy of his intellectual sincerity. Fechner was at once a scientist and a mystic. Torn by rival intellectual claims, he was totally incapable of giving up one for the other and equally incapable of peace without victory....

[Not] only was he thoroughly conversant with the science of his day; he was profoundly impressed, both emotionally and intellectually, by science as such -by its exact and rigorous methods, by the orderly nature of the world it it revealed. He found its views and its ways impossible to ignore. But over against the world of science he set the world of values, which [empirical] science did not heed, but which he found equally real, equally legitimate, and equally compelling as an object of intellectual concern. In his youth, Fechner had been deeply impressed by the philosophy of Schelling and the experience left him with a lasting sense that to ignore the immediate appeal of life and mind was to turn aside from immediately felt reality....

Under the strain his health gave way but in spite of his illness, he conducted experiments on positive afterimages -borderline phenomena, it is to be noted, between the mental and the physical worlds. In doing so he injured his eyes nearly to the point of blindness. His health broke completely. He resigned his position and lived for three years almost completely cut off from the world, a victim of illness, pain, and depression....

He recovered, ... on the morning of October 22, 1850... [when] he came upon an idea that satisfied both the scientific and the humanistic demands of his nature. It occurred to him that there might be an observable, even measurable relationship between the stimulus and the sensation and therefore between the physical and the mental worlds.... It is possible, then, that sensation may increase in arithmetical progression as the stimulus increases in geometrical progression. Sensation itself cannot be measured directly, but the stimulus can, and it may be possible to show that an increase in the stimulus by a constant fraction of itself is regularly correlated with every discernible increase in the sensation. In other words, an exact quantitative relation may be found between the physical and the mental worlds. To Fechner, the conception was an utterly satisfying one; if confirmed, it would bind together what had seemed disconnected and irreconcilable; it would give him the sense of world-unity that he had always craved -a world-unity, moreover, that he would be able to demonstrate by exact, mathematical evidence" (Heidbreder, 1933, pp. 79-81; emphasis added).

We should note that Heidbreder's use of terms like "victory, rival claims, values, and unity" are not accidental. They reflect the continuing disciplinary situation which Fechner was facing and attempting to surmount. She also does a very good job of relating Fechner's enthusiasm and genuine concern on issues which concern us all, including the issue of the possibility of psychology "as a science." Kant (1781), in particular, had claimed that psychology could never become a science because mind could not be subjected to "mathematical or experimental" methods of investigation. The activities and the contents of the mind could not be "measured," and therefore an objectivity such as that achieved in physics and chemistry was out of reach. Psychology would forever remain subjective. Fechner's (1860) counter-argument was that since psychological events are in fact tied to measurable physical events in a systematic and predictable way, psychology could be a science after all!

The specific means of Fechner's solution was to convert "Weber's constant" into an equation which is now known as the Weber-Fechner law (S = k log R) -with sensation on one side and stimulus on the other. More specifically, S and R stand for German words, where S is sensation (not stimulus) and R is "rinem," stimulus (not response). Thus, reasoned Fechner, any given sensation could be predicted as equivalent to the constant (k, or the Weber fraction determined empirically for that sense modality), times the logarithm of the particular stimulus in question. The equation, Sensation=k log R(Stimulus), says literally that the strength of a mental sensation equals a constant logarithmic (mathematical) function of the strength of the stimulus. In other words, it says that as the discriminated 'mental series' increases arithmetically, the 'stimulus series' must increase geometrically.

The important thing for us, however, is not to get bogged down in these specific details, but to recognize that this formula was intended by Fechner as a "mathematical bridge" between the object (stimulus) on the one side and the perceived sensation on the other. He believed he had thereby overcome the Kantian epistemological object-subject dualism. What he actually did, however, is replace it with a psychophysical version of double-aspect theory in which the strength of unobservable mental events would be physicalized operationally by way of mathematics. This is a description of, and means of predicting, the strength of the resulting isolated sensations arising from a given laboratory situation, but it is hardly an explanatory account of the nature of those sensations as they occur to or function within the perceiving organism. Fechner's equation simply defines the "sensation end" of the formula in terms of the "stimulus end." It does not state the practical, developmental, or organismic relations between them.

As in the case of Müller, what we can appreciate most about Fechner is his recognition of and motivation to find a solution for the methodological (subject-object) problem, but we must also acknowledge that given the pre-evolutionary context of his thought, he was unable to resolve it sufficiently. Subsequent workers in psychophysics (including Helmholtz) would consequently abandon Fechner's wider "metaphysical" concerns and concentrate instead on the more myopic pursuits of measuring what they could.

The mathematical-measurement side of Fechner's efforts (the belief that one can measure specific psychological characteristics albeit indirectly and perhaps learn something about them) can be said to have helped stimulate subsequent experimental psychology and individual differences research. I suppose, however, that it is just as apt to close our coverage of Fechner by mentioning that this was just the sort of empirical-experimental psychology which the quintessential late 19th century evolutionary thinker William James (1890; 1892) found so very sterile and dull (see Section 4).

Hermann Helmholtz (1821-1894)

Born in Potsdam (near Berlin) to parents of modest teaching and military backgrounds, young Hermann showed early promise in physics, but was trained as a surgeon at the Berlin Institute in exchange for service to the Prussian Army. During this period of training (1838-1842) Helmholtz studied physiology under Johannes Müller (then at the height of his institutional power), and actively mixed with Müller's University of Berlin students. It was at this time that Helmholtz established long-lasting relationships with DuBois-Raymond, Virchow and Ludwig who all swore to reject vitalism.

While serving out his military obligation in Potsdam, Helmholtz set up a makeshift physiological laboratory. Due to the wider import of his initial research (on metabolic processes in frogs) as well as his active discursive role (1847) in the ongoing emergence of the conservation of energy doctrine, Helmholtz was released early from Army service. Between 1849 and 1871, he went on to three professorships in physiology. At Königsberg (Kant's university) he both measured the rate of nervous impulse (in frogs and humans) and invented the ophthalmoscope (1851). At Bonn (1856-1858) he extended his interests to acoustics. During a longer stay at Heidelberg he proposed the Young-Helmholtz theory of color vision (1860) and the resonance theory of hearing (1863). In 1871, however, Helmholtz was finally appointed to the University of Berlin (in physics) where he occupied himself with the further application of the conservation law to the areas of hydrodynamics and electrodynamics.

We will consider four aspects of his approach to the physiology of the senses: (1) his rejection of vitalism in favor of a reductive experimental-materialist account of nervous impulse and sensory transduction; (2) his adoption of an indirect realist "enrichment" theory of perception -whereby undifferentiated sensory elements plus unconscious inference are said to establish contact with the world; (3) his rationale for favoring "empiricism" rather than nativism regarding perception of space; and (4) his disciplinary import for later developments including the limiting of empirical method to well-trained, immobile, adult human subjects.

James J. Gibson's (1966, 1979) direct realist "differentiation" theory of perception will also be introduced here as a basis upon which to surmount the difficulties of points 1-4 above, as well as to provide a standard by which we can then evaluate post-Helmholtzian disciplinary debates in Wundt, Külpe, and Titchener regarding the issue of higher mental processes. For to really understand Helmholtz is to understand the initial means by which active, everyday, natural observers looking around or listening to objects in the world become analytically reduced to passive, constrained, though well-trained "observers of sensory elements" (looking at, or receiving auditory stimulation from laboratory apparatus).

Opposition to Müller's vitalism

Back in his Berlin student days, Helmholtz entered into an antivitalist alliance called the "Physicalist Club" and promised to appeal to "No other forces than common physical-chemical ones... within the organism." This was to be a reductive "physiological" rather than a mechanical materialist position. Its aim would be to apply the "law of the conservation of energy" (i.e., that energy could be transformed from one state to another, but never created or destroyed) to "living organisms."

Similarly, in opposition to the nativist structural aspect of Müller's position on perception (which seemingly locked the organism into a loop of reference merely to its own nervous energies), Helmholtz would adopt a practically guided Lockean position which "got on with the job" of empirically investigating the senses without becoming mired in the metaphysical debates of German philosophy. As Boring (1950) points out, Helmholtz was more "British" than German in this aspect of his basic methodological assumptions. His was to be an experimental-physiological account of both the rate of nervous impulse and sensory transduction which appealed to no mysterious vital force or unknowable object.

The questions Helmholtz asked were essentially empirical: "How fast is the neural impulse of motor versus the sensory nerves?"; "By what means is physical energy from objects transduced in the senses of vision and hearing?"; and "Is perception of space learned or given to the senses innately?" With regard to the first two questions, we should note upfront that they are relatively straightforward matters of experimental evidence which Helmholtz answered very well. The latter question, however, was framed within an implicitly held enrichment theory of perception which he shared with his nativist opponents and therefore was not answered well by Helmholtz or by many others who followed.

Speed of nervous conduction

For Helmholtz, casting off the belief in any ubiquitous non-material force led him to question Müller's unexamined position that the brain delivered willful commands to the muscles in an instantaneous unmeasurable manner. The immediate impetus for his empirical interest in this issue of nerve conduction rate was the theory of DuBois-Raymond (1845) -a fellow Physicalist Club member- who suggested that if the nervous impulse involved a physical-chemical transduction rather than an immaterial act of will, it might also take enough time to be measurable.

By 1850 Helmholtz was measuring the rate of impulse in the motor nerve of severed frog legs. This was done by setting up a laboratory galvanometer with a known rate of deflection of its needle so that it is switched-on when the nerve is stimulated and switched-off when leg contraction disconnects the circuit. Thus, deflection of the galvanic needle provided a time interval for each of the successive stimulations applied at known distances along that motor nerve. A simple mathematical computation of known distance versus known time-lapse could then be worked out to establish the average rate it took for the impulse to traverse each distance:

"I have found that there is a measurable period of time during which the effect of a stimulus consisting of a momentary electrical current applied to the iliac plexus of a frog is transmitted to the calf muscles at the entrance of the carrel nerve.... the stimulation of the nerve was given by means of an induction coil. By means of a special mechanical device, a second electrical current was transmitted to a galvanometer at the moment the original current was transmitted to the induction coil.... The current flowed through the induction coil until the stimulated gastrocnemious muscle had contracted sufficiently to lift a weight... The lifting of the weight interrupted the current to the induction coil and to the galvanometer. The duration of the current, therefore, was exactly equal to the period elapsing from the application of the stimulation of the nerve to the commencement of the mechanical reaction of the muscle" (Helmholtz, 1850, In W. Dennis, 1948, Readings in the History of Psychology, p. 197).

Finding the results fairly regular and consistent, Helmholtz estimated the overall average speed of the frog's motor nerve conduction to be about 30 meters per second. Baxt (1867) modified the procedure for human subjects estimating the rate of motor impulse at about 33 meters per second. This was done by stimulating the nerve to the ball of the thumb, either at the wrist or above the elbow (thereby producing a twitch), while the hand, forearm and elbow were held motionless in a plaster cast.

Meanwhile, back at Königsberg, Helmholtz had already moved to the more tricky task of measuring sensory nerve conduction in intact human subjects. This was done by way of stimulating the toe or thigh (respectively) and having the subjects 'report' (by pressing a telegraph key) as soon as they detected each stimulation. The results were so variable that Helmholtz declined to make any proclamation on the speed of sensory nerves. It was only later that F.C. Donders (1868), -who had initially set out in searching for a universal mathematical psychological constant similar to that of Newton's law of gravity- distinguished between simple discrimination and choice reaction times (which he found to increase in duration and variability respectively). In other words, the task of estimating sensory nerve impulse rates turned out to be far more complex than first anticipated.

Thus, aside from having obtained a positive answer to the old Kantian question regarding measurement ("Can we measure psychic events?"), the most important methodological generalization made from this Helmholtzian era research was that the merely additive model doesn't work. It was too simplistic to cover the observed irregularities of the measurements made. More complex mathematical and theoretical models of the nervous system (those beyond the scope of the contemporaneous pre-evolutionary knowledge) would be required to account for the observed empirical variability of such data.

Helmholtz, however, was content to put aside these deeper methodological considerations (for later analysis by others), and moved on instead to a closer consideration of the anatomical-physiological aspects of sensory transduction in particular. For, unlike Fechner or Donders "Helmholtz was not given to brooding about the unity of the universe. He wanted to know, among many other things, exactly how the eye and the ear worked... [So] he invented apparatus, devised experimental methods, and constructed theories [accordingly]" (Heidbreder, 1933, p. 85).

Account of sensory transduction

Instead of getting bogged down in metaphysics, Helmholtz held to the attitude that the more we learn about sensation the better; and, further, that perhaps by virtue of carrying out empirical research (and by proposing albeit contentually circumscribed theories), the metaphysical issues might someday resolve themselves. His two major works along this line of inquiry (Treatise on Physiological Optics, 1856-1866; and Sensations of Tone, 1863/1875), therefore, are characterized by a convenient convergence of the physiological, philosophical, and experimental traditions of empiricism as they applied specifically to the empirical aspects of sensory transduction.

While the experimental aspects of these works foreshadow the Wundtian laboratory psychology to follow, their equally prevalent reductive sensory-element aspects were then picked up by E.B. Titchener, brought over to America, and still live on in the contemporary (and highly problematic) subdiscipline called "Sensory Processes." As for the philosophical assumptions, they remained muted in Helmholtz and became unquestioned in the subsequent North American elaboration. They did not, however, go away. Nor did they resolve themselves as Helmholtz had hoped. So, we will want to understand a bit about each of these 'experimental, reductive, and philosophical' aspects as we proceed.

The primary and explicit focus of the Helmholtzian empirical research was on the distinctly physiological investigation of sensory transduction in the retina (of the eye) and in the cochlear membrane (of the ear) respectively. In part, this empirical focus was an extension of Müller's "specific energies of nerves" hypothesis to the qualities of particular sensory modalities. In other words, both his trichromatic theory of retinal transduction and his resonance theory of auditory transduction were posed as accounts of how physical energy was being transduced into the neural energy of Müller. This is all well and good (as far as it goes); and his account of such sensory transduction still holds up relatively well today.

Physiological optics versus psychology

The issue for us, however, is to recognize that in his initial attempts to apply the procedures of the physiological laboratory to psychological topics, certain problematic assumptions were imbedded in the way Helmholtz laid out the respective tasks to be addressed by the physicist, physiologist, and psychologist. Helmholtz (1866) certainly recognized that there must be a division of labor in the science of the senses and (as Brauns, 1997, points out) he laid out this division as follows:

"Whereas physical optics deals with the 'pathway of light in the eye' and physiological optics focuses on the 'theory of sensations in the visual apparatus,' psychology is concerned with 'the theoretical understanding of visual sensations, including the ideas, which are developed about objects in the external world on the basis of visual sensations'" (Helmholtz, 1856-1866, p. 30; as quoted in Brauns, 1997, p. 109).

The work of Helmholtz shines brightly with regard to the first two tasks outlined above, but it is in the definition of the latter psychological task as well as in the limitations on method imposed by that definition where the problems of his admittedly early account reside. Stated plainly, we are about to show that his definition of the psychological task starts from a rather reductive assumption that perception is built up from sensory elements and, further, that the indirect (enrichment) theory of perception which he adopts as a result of this definition imposes (in turn) unwarrantable limitations on both his account of proper experimental method and on his application of this method to specific psychological topics like space perception. We must, therefore, highlight these implied aspects of his work in a manner which Helmholtz would not have been able, or perhaps even willing, to do himself.

Indirect realist (enrichment) position

First off, Helmholtz takes it for granted that perception is built up from combinations of sensory elements which are concurrently supplemented with intellectual qualities (along the line of Locke's secondary qualities). Perception, he suggests, begins with simple undifferentiated sensations received rather passively through anatomical channels in the sensory apparatus of both humans and animals. But as Gibson (1966) would later point out, whenever the world is considered as not directly revealed to us but only signified indirectly through undifferentiated sensory elements, some additional intellectualizing principle is required to get out there to the external world. In order to avoid being trapped in the old philosophical 'barrier of the senses,' therefore, Helmholtz suggests that elementary sensory elements are supplemented by unconscious inferences which attribute these elements to external objects:

"The general rule... whenever an impression is made on the eye, with or without the aid of optical instruments [(spectacles, telescope, or microscope)], is that such objects are always imagined as being present in the field of vision as would have to be there ... under ordinary normal conditions.... The psychic activities that lead us to infer that there in front of us at a certain place there is a certain object of a certain character, are generally not conscious activities, but unconscious ones. In their result they are equivalent to a [logical] conclusion.... But, moreover, just because they are not free acts of conscious thought, these unconscious conclusions from analogy are irresistible, and the effect of them cannot be overcome by a better understanding of the real relations" (Helmholtz, 1866; In Herrnstein & Boring, 1966).

Note that according to Helmholtz, the "real relations" means simply that sensations and not objects are the stuff to which our perceptual apparatus (retinas, choclear membrane, etc.) refers; and that he is also implying that while this is especially true in the physiological vision laboratory, it is also true of "ordinary normal conditions" in everyday life. It is in this manner that Helmholtz presents his rather static, anatomically fixated account of perception which retains an albeit intellectually qualified indirect perception theory.

As Boring (1950) pointed out, this is an account of perception which is very similar to that of J.S. Mill's (1865) -where perception is defined as the "permanent possibilities for sensation." Having made this cogent observation, Boring promptly drops the matter (p. 313). Indeed, until relatively recently (with Gibson's respective 1966 and 1979 critiques) this sort of indirect account (that we are acquainted only with the qualities of our nerves, or neurons, or retinal locales; but not with the properties of the external world) seemed to be the unassailable basis for any physiological theory of perception.

Knowledge for Helmholtz and many others thereafter begins with uninterpreted sensory building blocks which can not be appreciated except by a special act of attention and which are typically then unconsciously and automatically supplemented by unconscious intellectual inference. After all, if we only have the anatomical deliverance of sensation to go by, we must have to somehow intellectually deduce or induce the worldly causes of these sensations, for we can not detect them directly.

As for the kind of "special acts of attention" he is referring to, Helmholtz suggests that if one is standing on a hilltop surveying a wooded landscape, the normal blending of color in green foliage and blue sky can be appreciated as being made up of fine gradations of a multitude of simpler shades if one turns one's back from that landscape and views it upside down though one's legs! Other special acts of attention can be carried out by trained laboratory observers too, and it is here that we begin to gain a better appreciation of how the assumed indirect perception theory of perception can lead (so to speak) researchers toward investigating very abstract (unnaturalistic) forms of questions through highly constrained laboratory procedures.

Definition of "vision" and proper method

Just how this inferential (enrichment) theory played out in terms of defining appropriate subject matter for and methods of investigation can be shown by looking at comments made by Helmholtz on vision and methods. First of all, Helmholtz defined vision itself as "pointing the eyes" (as looking-at rather than looking-around).

"[T]he intent of vision, is to see as distinctly as possible various objects or parts of an object in succession. This is accomplished by so pointing the eyes that an image of the given object is projected on the fovea of each retina. The governing of the ocular movements is wholly subordinated to this end; both eyes are adjusted and accommodated together so as to permit this light absorptive pointing" (Helmholtz, Physiological Optics, 1866/1925, p. 56).

According to this definition, "vision" (at best) involves eye movements relative to the head. The implication for method of study, therefore, is that the natural proclivity of a naive observer to look around must be constrained and controlled out of the laboratory setting. In such studies, the eyes of an observer would sometimes be allowed to scan a stimulus display with the "field of view" being limited to that of a stationary head which was often physically restrained by an apparatus such as a chin rest. At other times, however, the eyes of the observer would have to be held as still as possible so that the stimulus display would fall on the foveal region of the retina (on the anatomical region of maximum acuity). The sensitivity of various points on the retina to color or level of illumination could thereby be mapped.

Helmholtzian type sensory research. Left: Monocular acuity study with presented stimulus display; Right: Vertical section of an observer's monocular field of view. At this temporary (and stationary) eye and head posture, the surfaces projected into the retinal image are indicated by solid lines and the remaining surfaces by dashed lines. The "awareness of the here-and-now surfaces might be called viewing the room as distinguished from seeing the room" (from Gibson, 1979, p. 196).

The question we repeatedly bump up against when considering Helmholtzian type sensory research, is one of levels of analysis: Is some sort of stimulation of the retina necessary for visual perception to take place? Yes! Is such anatomical stimulation sufficient for perception to take place? No! Recall, for instance, that Müller pointed out that mechanical stimulation of the retina by a finger (in the dark) produces sensations of light without perceptions thereof. Similarly: Is the constrained looking of the physiological laboratory one aspect of vision? Yes. Is it sufficient to explain vision? No! As J.J. Gibson (1966; 1979) would later point out, normal (everyday, active) visual perception (looking around) is not a matter of intellectual enrichment of inputs to discrete anatomical sensory receptors but rather one of differentiation of the environment by way of sensory systems:

"One sees the environment not with the eyes but with the eyes-in-the-head-on-the-body-resting-on-the ground.... The perceptual capacities of the organism do not lie in discrete anatomical parts of the body but lie in systems with nested functions" (Gibson, 1979, p. 205).

Gibson (1979) also comments directly on Helmholtz stating that:

"He assumed that [sensations from] objects and parts of objects are what we perceive and that these are limited to objects in the fixed field of view. He would be astonished at the assertion that a man perceives his surroundings, including the environment behind his head, for that is not 'the intent of vision'" (Gibson, 1979, p. 206).

Since, according to Helmholtz (1866), the analysis of perception into its sensory constituents takes place by a special act of attention, only trained subjects who can accurately report on sensations must be used because our naive attention is constantly directed back at objects and wholes:

"Another general characteristic... of our sense-perceptions is, that we are not in the habit of observing our sensations accurately.... thus in most cases some special assistance and training are needed.... [Experience] shows that for the discovery of subjective sensations some special talent is needed, such as Purkinje manifested.... [or as in] the phenomena of the blind spot... discovered by Mariotte.... Even the afterimages of bright objects are not perceived by most persons at first except under particularly favorable external conditions. It takes much more practice to see the fainter kinds of afterimages.... Accordingly, the first thing we have to learn is to pay heed to our individual sensations. Ordinarily we do so merely in case of those sensations that enable us to find out about the world around us. In the ordinary affairs of life the sensations have no other importance for us.... The same difficulty... occurs... in trying to analyze the compound sensations... excited in ... connection by any simple object, and to resolve them into their separate components. In such cases experience shows us how to recognize a compound aggregate of sensations as being the sign of a simple object. Accustomed to consider the sensation-complex as a connected whole, generally we are not able to perceive the separate parts of it without external help and support.... For instance... being able to distinguish those parts of the retina where light falls from those parts where it does not fall" (Helmholtz, 1866, In Herrnstein & Boring, 1966, pp. 155-156).

Helmholtz is attempting here to emphasize the careful procedures to be followed in the training of subjects, yet in doing so he makes rather manifest the lack of wider (ecological) validity of such research. If we are in fact naturally drawn to wholes and to perception of visual laboratory displays as objects, the logical question to ask is: Why would this be the case? Even though he is writing during a period in which the theory of evolution has yet to be drawn into psychological discourse, Helmholtz does answer this question in part when he says: "In the ordinary affairs of life the sensations have no other importance for us." Put this statement together with his other statements on the importance of light itself and one has the makings of a solution to the problem.

It would be a very long time, however, before Gibson (1966) would push this admittedly honest analysis by Helmholtz (1866) one step further by giving up the fundamental assumption of the retinal image as anything more than just that -a stimulus for retinal transduction. In the following extract, Gibson admits openly that this was, even for him, a gradual and uneasy theoretical shift to make:

"Only in the last few decades has the evolution of vision become clear, with some understanding of function as well as of anatomy. The long treatise by Walls on The Vertebrate Eye (1942) is a monument to this progress, and it provides much of the groundwork for this chapter. The comparative study of visual perception is now possible, and evidence is accumulating. This approach is quite different from the traditional one [which Gibson himself had held to for many years]. The classics of vision were unaffected by evolutionary considerations or by knowledge of animal behavior but nevertheless they [still] dominate the theories of perception. The two greatest were probably Berkeley's New Theory of vision in 1709, and Helmholtz' Physiological Optics in 1865. Both were preoccupied with the puzzle of how men could see depth and distance in the face of the fact that retinal images were flat and visual sensations were depthless. Another landmark in the history of the subject, Koffka's Principles of Gestalt Psychology (1935), was mainly concerned with how we see an object in relation to its framework, a figure on a background, and it kept to the question of why things look as they do to us.

In my book, The Perception of the Visual World (1950), I [originally] took the retinal image to be the stimulus for an eye [along the lines of Helmholtz]. In this book I will assume that it is only the stimulus for a retina and that ambient light is the stimulus for the visual system. This circumstance, the fact of information in the light falling upon an organism, is the situation to which animals have adapted in the evolution of ocular systems. The visual organs of the spider, the bee, the octopus, the rabbit, and man are so different from one another that it is a question whether they should all be called eyes, but they share in common the ability to perceive certain features of the surrounding world when it is illuminated. The realization that eyes have evolved to permit perception, not to induce sensation, is the clue to a new understanding of human vision itself" (Gibson, 1966, p. 155).

This theoretical shift, from retinal image to ambient light as the stimulus for visual perception, was not only required to reassert theoretical parsimony and ecological relevance back into the area (see Reed & Jones, 1982), it was also necessary to explain the many empirically untidy loose ends left dangling and unresolved by the older theory. In short, the cumulative mass of data which had accrued in the ensuing 100 years between Helmholtz (1866) and Gibson (1966) was yet to be sifted through and ordered. Foremost among the data left unexplained by the older theory was Eleanor Gibson's research on the "visual cliff," which presented a distinct and particular challenge to the Helmholtzian view of space perception. So, we will want to drive the point home by considering how this shift in theory supports and improves the positive aspects of Helmholtz while surmounting its weaknesses.

Perception of space

In opposition to the Kantian aspects of Müller's approach to spatial perception, Helmholtz (1866) puts forward an attempted strickly physiological Lockean position. His statement of why he holds to an empiricist position regarding perception of space is quite telling in this regard:

"I am aware that in the present state of knowledge it is impossible to refute the [Kantian] intuition theory. The reasons why I prefer the opposite [empiricist] view are because in my opinion: ....the adherents of [the nativist] theory are, ... obliged to make the questionable assumption, that the space sensations, which to them are present originally, are continually being improved and overruled by knowledge which we have accumulated by experience.... In that case it would seem to me much easier and simpler to grasp that all apperceptions of space were obtained simply by experience..." (Helmholtz, 1866, In Herrnstein & Boring, 1966; emphasis added).

The main point of departure between Helmholtz and those he is arguing against is one regarding the matter of what is being "improved" (enriched) to gain perception of space: For Descartes it was innate ideas; for Kant, it was our appreciation of a priori categories of the mind; but for Helmholtz, it was original sensory elements that are being enriched. He considered the relevant disciplinary divide to be addressed as one between nativism and empiricism. What he didn't recognize, however, was that he shared a long-standing and discursively embedded idol of the theater with those who he was arguing against: The Indirect (enrichment) theory of space perception.

The key point for us to note is that Helmholtz holds to an enrichment theory of perception (which is a shared limitation with nativists like Descartes, Kant, and Müller) rather than a direct differentiation theory which only appears periodically before 1866 (in Reid and Brown) and even thereafter (in James, the Gibsons and their students). This shift in thought regarding perception from indirect representationalist theory toward direct ecologically valid theory is the most significant movement in psychological thought to have occurred in the 20th century and its far-reaching implications for method and subject matter are still being worked out.

With regard to its implications for the particular limitations of Helmholtzian views on space perception, however, it has been pointed out by Fancher (1990), that Eleanor Gibson's visual cliff experiments present a significant challenge to the learning hypothesis as stated in the Physiological Optics (1866). So, let's briefly consider what the exact challenge actually is, as well as introduce the wider disciplinary implication of that challenge.

First of all, Helmholtz (1855) had observed that young children make many perceptual mistakes such as believing that people in tall towers are "dolls" which can be reached out to and grasped (see Herrnstein & Boring, 1966, pp. 128-129). Later on, he also carried out experiments with adult subjects showing that the use of special spectacles which displaced the normal visual angle (say 5 degrees left or right) presented immediate difficulties to reaching and pointing, which after a few minutes are adjusted to by way of active practice under these new conditions. Helmholtz (1866) called this "perceptual adaptation" and suggested that, at the very least, this sort of evidence indicates that space perception is experientially malleable. Subsequent versions by Stratton (1897) and then Ewert (1930) were carried out using prismatic goggles, -which took longer to adjust to because they distorted the normal visual field more severely- but produced similar results. Subjects would learn to move about the laboratory and the university campus after a time and would also have to unlearn the adjustments upon removing the goggles (see also T. Erismannn & I. Kohler "Living in a Reversed World"; and I. Kohler, 1962 in this regard).

As a result of his own observations and experiments, Helmholtz invoked the principle of theoretical "parsimony" to argue that space perception is probably a learned (acquired) ability in the first place. In the ensuing years after Helmholtz, it was well recognized that: "The [original] question separating empiricist for nativist -Helmholtz from Kant- was not whether any perceptual processes were acquired through experience, but how many and to what extent" (Fancher, 1990, p. 126).

What was not widely recognized, however, was that both nativists and empiricists (up to and including J.J. Gibson, 1950) all adhered to various versions of the same enrichment theory of space perception. Simply stated, this theory has to be shed if one is to appreciate the disciplinary significance of the "visual cliff" experiments. Thus, when Eleanor Gibson & Richard Walk (1960) presented their visual cliff data in Scientific American, their results were immediately (and mistakenly) taken as support of the nativist side of the old enrichment argument. In fact, however, neither their data nor their analysis of it supports either side of that old pseudo-dichotomy. Instead, it supports a 'third' alternative (or rather kind of approach) to space perception which falls well outside them both! So, let's finally look at the studies that caused such a fuss and consider their implications.

Visual Cliff Research (after Gibson & Walk, 1960, Walk & Gibson, 1961). E.J. Gibson and Richard Walk (1960) studied infant’s depth perception by using a small cliff with a drop-off covered by glass. The visual cliff apparatus consists of a raised central platform with a horizontal sheet of plate glass on either side. Under the glass, on one side only, there is a large drop to the ground below -this is the 'cliff'. Walk & Gibson (1961) expanded the analysis to the comparative realm by assessing the performance of other species on the same apparatus. The empirical question at issue was rather straightforward: At what age will different animals, placed on the central (raised) platform, move only to the shallow side and avoid the 'visual drop'? -thus signifying that they can perceive the difference in distance to the ground below. The proper theoretical interpretation of the results, however, is still a matter of debate between those who retain the problematic enrichment theory of perception and those who have now accepted the Gibsonian differentiation theory.

In Gibson & Walk (1960), 36 human infants (between the ages of 6 and 14 months) were placed on the central board of the visual cliff apparatus, between the two surfaces. Their mothers called to them from the cliff side of the setup and from the shallow side successively. Of the 27 infants who moved off the central board, all of these crawled to the shallow side indicating their depth perception is well enough developed to avoid the potentially dangerous deep side.

Similarly, Walk & Gibson (1961) tested the performance of other species on the visual cliff apparatus under the conditions of food incentive. Chicks (under 1 day old), lambs, goat kids, normally raised kittens, and monkey infants all avoid the deep side of the visual cliff as soon as they can move about on their own. Exceptions to this rule, however, were found including: 4-week-old kittens that had been reared in the dark (which did not avoid the deep side); and rats that could apparently detect the glass surface with their whiskers (see also Walk, Gibson, & Tighe, 1957; Walk, 1966).

The visual cliff apparatus was originally designed to test infants old enough to crawl but research by Campos showed that 9-month-old infants had faster heart rates than normal when placed on the deep side (presumably because they were frightened) while infants aged 2-5 months actually had slower heart rates than usual (suggesting that they were not frightened). This slowing of heart rate certainly indicates that they detected some difference between the deep and shallow sides of the visual cliff situation and probably reflected interest in this difference (Campos, Langer, & Krowitz, 1970; Campos et al., 1978). Later studies with human infants also confirmed that experience with crawling is related to avoiding the deep side of a visual cliff (Rader, Bausano, & Richards, 1980; Richards & Rader, 1981). Further, Rader's experiment noted that pre-toddler babies avoid a visual cliff when crawling but go over the edge when in walkers. Hmm, that's interesting, why the heck would they do that?

While all of this initial empirical data was fairly uncontroversial, the theoretical interpretation thereof has been a more complex matter of debate. First of all, proponents of the old enrichment theory were immediately divided (amongst themselves) along traditional nativist vs. empiricist lines. Thus, 1960s-1980s textbook accounts claimed that either the data indicates that some aspects of depth perception are "inborn," while others claim it is "learned," and still others suggest a "bit of both."

Simply stated, if one attempts to utilize the old enrichment theory in considering this data, you are left scratching your head. For instance, if past experience is brought to bear on sensory inputs to produce perception of depth (as Berkeley, Locke, and Helmholtz had suggested), then why do day-old chicks avoid the visual cliff? On the other hand, if inborn categories or abilities are involved (as Kant and Müller had suggested), then why aren't 2-5 month old infants afraid of being placed over the deep end of the apparatus? Similarly, if depth perception is fully active in babies who can crawl, why do they willingly traverse the visual cliff when they are set into walkers? Why do they fail to attend to the cliff when afforded this greater mobility?

This latter empirical observation, in particular, posed a significant logical conundrum for subsequent cognitive theorists (including Neisser, 1967) whom would initially argue against the reductive (passive-mechanical) behaviorist position by suggesting that "learning and cognitive development" was a matter of active (though roughly additive) attentional accrual and transfer of past associations. But the visual cliff experiment had already shown that the development of space perception in pre-toddlers is by no means an additive affair! In other words, the enrichment theory (in either its extreme or even moderate forms) is not sufficient to explain the known facts and therefore must be abandoned in the light of those facts.

Parenthetically, during the late 1980s and early 1990s the tendency in introductory psychology textbooks was to pull back from earlier nativist or additive associationist overstatements by either omitting mention of the visual cliff data altogether (e.g., Levine & Shefner, 1991); or by avoiding making any theoretical statement on the disciplinary significance of the data (e.g., Atkinson et. al., 1990; Garrison & Lefton, 1994; Myers, 1995).

Fortunately, however, that defensive posture began to be overcome in 'perception' textbooks (e.g., Goldstein, 1989; Sekuler & Blake, 1990; Matlin & Foley, 1992) and in 'cognition' texts (e.g., Neisser, 1976, 1982, 1987; Benjafield, 1992; Neisser, 1993) which started to mention that an alternative "Gibsonian theory" exists. In short, it is becoming clearer that the traditional innate vs learned dichotomy was just a counterproductive disciplinary side-issue and that the real theoretical issue to be considered is between the old indirect "enrichment" theory (in its various formulations) and the relatively newer direct "differentiation" theory of perception (Gibson & Gibson, 1955; Gibson, 1966, 1979).

As Lombardo (1987) put it, both Eleanor and James Gibson (1960 onward) viewed perceptual learning not as matter of indirect "supplementation" but rather of direct developmental "differentiation" (see E. Gibson, 1969, 1984; Lombardo, 1987; Reed, 1988a). Perceiving gets wider, longer, richer, and fuller as the organism investigates the environment over time; and the kinds of things it investigates (becomes aware of) includes surface layout. While visual perception predominates in adult human beings a host of other sensory systems are also used in perceptual learning and these other systems actually predominate during the early ontogenetic development of human infants. Further, the relative importance of each system varies depending upon the organism under consideration (e.g., human, kitten, rat, goat, etc.).

The Gibsonian account of perception is therefore both evolutionary in that it includes a comparative-vertical 'levels of analysis' aspect and functional-developmental in that it includes an active-temporal-ontogenetic aspect. Intellectual enrichment of impoverished, transitory, sensory snapshots or other forms of supplementation of elemental sensory building-blocks are given up for reference to successively wider differentiation (pickup) of perceptual information from the world over time.

In the particular case we are considering, the only way to account for the observed empirical facts of the visual cliff experiments is to accept that a third dimension (space) is not added to impoverished visual sensations (to two-dimensional retinal images), and recognize instead that the development of depth perception itself is a nonadditive, emergent, "reciprocal" process involving both education of attention in the organism and successively expanding differentiation of a visual system which that education allows.

The visual depth information is there in the optic array to be had by the normally developing organism (regardless of past experience) and as the organism matures it learns to differentiate (pickup) more of this information. The development of visual perception does not just involve changes in the organism itself, but rather in the wider reciprocal (subject-object) relation. The task for comparative and developmental psychology therefore becomes one of working out the continuities and discontinuities (phylogenetic, ontogenetic, and socio-historical) in that active, expanding, subject-object unit of differentiation.

As for the lack of visual space perception in the case of the dark-raised kitten, this is to be expected due to the artificially contrived deprivation conditions in which it has been raised. These kittens, in fact, are approaching the world from the standpoint of their other sensory systems, just as in the rat which relies primarily not on its visual system but on its proprioceptive whiskers and kinesthetic-body system to pickup surface layout (see Harvey Carr's classic "Kurplunk" maze experiment where maze-trained rats were found to smash headlong into new barriers place in the path of a previously learned route). The visual cliff is simply not ecologically relevant for the rat because its whiskers and front paws have already informed it that the glass surface affords walking.

Finally, the willingness of pre-toddlers to traverse the visual cliff when placed into baby-walkers remains to be explained. This can be done by noting the relative shift in dominance between proprioceptive-kinesthetic and visual perceptual systems which is occurring along with the normal, active, developmental transition from crawling to walking. First of all, although the original Gibson and Walk studies found that competently crawling infants avoid the 'deep side' of the visual cliff, later research by Campos and colleagues found that infants who have just started crawling are more likely to cross over the deep side of the visual cliff (while infants who have been crawling for about 4-6 weeks are significantly less likely to do so). Thus, while heart-rate data seems to indicate that non-crawling infants can detect and even fear the cliff (by 9 months), the greater mobility afforded by (and the greater mental effort required by) the new crawling ability seems (for a time) to overcome this fear.

In other words, when we consider what the newly crawling baby is attending to while traversing the world, the solution to this conundrum becomes clear. Like the rat, the proprioceptive-kinesthetic support provided by the glass is the deciding aspect. The visual system still does not fully predominate while performing these new crawling actions. Subsequent mastery of the mechanical aspects of crawling (thereby freeing the mental attention) and experience with falling soon thereafter brings about a gradual shift toward visual aspects of surface layout. Similarly, for a pre-toddler (already reticent to cross the visual cliff by way of crawling), the use of a baby-walker requires that attention must be given to its use. Further, the supportive proprioceptive-kinesthetic aspects of the walker (the still predominant means by which crawling babies move about in the world) afford the pre-toddlers with a confidence to traverse the cliff which they would not otherwise attempt.

Incidentally, as anyone who has visited the glass-floored "observation deck" of the CN Tower (in Toronto) will note, by the time of early toddlerhood, children will readily cross that visual cliff because they already understand that the glass affords walking. This is, however, in the CN Tower case a surprisingly more difficult task for adults to perform; and here we must refer to the influence of higher mental processes (and grave concerns) which go well beyond the abilities or considerations of the toddling child.

Disciplinary Importance of Direct Perception

It should be noted that the 1960s era Gibsonian (evolutionary, functional-developmental) approach to perception moves well beyond the influential though constrictive-reductive confines of "psychological" concerns proposed by Helmholtz (1866). Accordingly, any future systematic adoption of that newer approach will involve both a repudiation and reformation of numerous falsely restrictive representationalist approaches adopted during the interim (late 19th century) "disciplinary building" and (early 20th century) "schools and systems" eras of general psychology.

By emphasizing the methodological solution of direct perception at this early juncture, however, we will be in a better position to appreciate how adopting a non-reductive (emergent evolutionary and levels of analysis) definition of perception implies the further disciplinary need for a non-reductive redefinition of higher mental processes (see Reed, 1987, 1988). Having noted, rather provisionally, that the vertical dimension (higher-lower manifestations) of psychological processes still remains to be addressed in more detail, we'll now turn to the initial round of debates which occurred during the early years of the founding of the discipline now called psychology.

It was the issue of whether higher mental processes are able to be studied in the psychological laboratory; and/or whether they are reducible to lower "elements" of consciousness, that constituted the main matters of contention between Wundt and his students such as Külpe and Titchener. It will be demonstrated that it is Külpe that provides the soundest contemporaneous empirical-theoretical foundation for the discipline because while (unlike Titchener) he agreed with Wundt's antireductive account of higher mental "states," he suggested (along with Ebbinghaus and Titchener) that they could be studied within as well as beyond the psychological laboratory.

Definition of psychology

Before continuing on, it must be explicitly reiterated that the adoption (or lack thereof) of a direct theory of perception is fundamentally important to our very definition of psychology itself. As we will see, the various early textbook definitions of psychology (as opposed to physics) provided by Ernst Mach (1886), Wilhelm Wundt (1896), and E.B. Titchener (1896, 1910) were all framed within the constraints of an indirect representationalist position. That theory (as shown previously) provides no unequivocal access to objects or events in the world. The resulting early disciplinary definitions, therefore, divided up the respective subject matter of the sciences not with reference to existing levels of worldly processes but with reference merely to kinds of experience as follows:

Machimmediate experiencemediate (inferential) experience
Wundtmediate experienceimmediate experience
Titchener (point of view)independent experiencedependent experience

By way of dividing up the respective territory of the physical/natural sciences versus psychology on the basis of the old doctrine of primary (given) and secondary (inferred) qualities, Mach (1886) -the physicist turned part-time psychological investigator- suggested that physical facts (though only available to us by way of Humean sensations) constituted "the given" while psychological facts were definitively inferential (because in that case our "experience" works from the inside outward rather than from the outside inward).

"A color is a physical object so long as we consider its dependence upon its luminous source, ... upon space, and so forth. Regarding, however, its dependence upon the retina... it becomes... psychological..., a sensation. Not the subject, but the direction of our investigation, is different in the two domains" (Mach, 1886, Contribution to the Analysis of the Sensations, Sect. 8).

But Wundt (1896) -the physiologist turned psychologist- disagreed, suggesting instead the converse because (as Helmholtz seemed to have shown) physical facts (events in the world) must be inferred on the basis of immediately given sensory experience. Wundt turns Mach's "directional" argument around as follows:

"The expressions 'outer experience' and 'inner experience' do not indicate different objects, but different points of view from which we take... the scientific treatment of a unitary experience.... [E]very concrete experience... divides into two factors -a content that is presented to us, and our apprehension of this content. The first of these factors we designate as objects of experience, whereas the second is the experiencing subject.... The point of view of natural science may, accordingly, be designated as yielding mediate experience, since it becomes possible only after abstracting from the subjective factor... The point of view of psychology, on the other hand, may be designated as that of immediate experience..." (Wundt, Outlines of Psychology, 1896, Introduction to Sect. 1).

In other words, it was as though 'whomever gets there first' claimed the "immediate" (given) experience for their favorite scientific domain and left the relatively more problematic inferential ("mediate") experience for the others.

This dogmatic standoff over 'the given' of research domains did not escape the attention of Külpe or Titchener and they both appealed instead to the only other contemporaneously available 'alternative' view -that of Richard Avenarius; whose writings were suitably vague and voluminous enough to not only meet with the assent of Mach himself but also to avoid translation into English for many years (thereby affording Titchener relatively safe passage to America in the interim).

Külpe's Outlines of Psychology (1893; English Trans. 1895), for instance, defined psychology as the science of the "facts of experience" and suggested that our understanding of psychological content (experimental or otherwise) is characterized by the "dependency" of these facts on the experiencing individual. It was a variation of Külpe's approach, therefore, that was brought over to America by Titchener and elaborated in his "structuralist" system of psychology:

"If it is true that all the sciences have the same sort of subject-matter [experience], there can be no essential difference between the raw materials of physics and the raw materials of psychology.... All human knowledge is derived from human experience; there is no other source of knowledge. But human experience, as we have seen, may be considered from different points of view.... First, we will regard experience as altogether independent of any particular person; we will assume that it goes on whether or not anyone is there to have it. Secondly, we will regard experience as altogether dependent upon the particular person; we will assume that it goes on only when someone is there to have it.... In principle, then, introspection [in psychology] is very like inspection [in physics]. The objects of observation are different; they are objects of dependent, not of independent experience.... And the standpoint of the observer is different; it is the standpoint of human life and of human interest, not of detachment and aloofness. But, in general, the [observational] method of psychology is much the same as the method of physics" (Titchener, A Textbook of Psychology, 1910, pp. 16-27, emphasis added).

Similarly, the lack of unequivocal resolution in the initial round of disciplinary debates (in Germany) over the respective import or applicability of introspective, experimental, and phenomenological methods also springs from the commonly held problematic methodological assumption of indirect perception. An ostensibly "methodological" (rather than purely metaphysical) psycho-physical parallelism -portrayed as an interim working hypothesis- was assumed by Wundt (in his Logik, 1880-1883) with respect at least to experimental physiological psychology. Both Külpe (who demurred from Wundt's approach only with respect to the possibility of studying higher mental processes by way of experiment) and Titchener (who reduced higher states of consciousness to the lower elements which supposedly made them up anyway) conveniently fell into line along with Wundt in this regard.

Stated more plainly, no resolution on the issue of the respective import of the various empirical methods (let alone an unequivocal definition of psychology itself) could be worked out from within the constraints of the enrichment theory of perception. Since the supposed 'barrier of the senses' separates the subject from the object, some form of equivocal, self-serving psycho-physical parallelism whether it be claimed 'metaphysical' or not is always necessary given that indirect realist presupposition and only by rejecting it can we build anew.

It is only with the more "pragmatic," direct realist, and "functional" psychology of William James (and others up to about 1920) that the makings of a solution to these various disciplinary issues were first presented. But by that time classical behaviorism (a reductive, antimentalist trend to be sure but one that at least assumed unequivocal access to observable "behavior") and other forms of Logical positivist or operationist accounts were already on the rise in American general-experimental psychology (see Section 5). These latter trends, in slightly modified forms, were then carried forward into the late 20th century cognitive psychology era and would have to run their course before the developmental-evolutionary Gibsonian sorts of solutions would begin to be recognized as opening up new vistas for consolidation of definitions and for the resolution or surmounting of long-standing (previously unresolvable) issues.

Wundt, the Leipzig laboratory, and his rebellious students

Wilhelm Wundt began in the 1860s to expand what had been essentially physiological (psychophysical and reaction time) methods with the explicit disciplinary-building aim of objectively measuring a circumscribed set of rather basic psychological phenomena. He then moved on (after a considerable period of professional struggle) to found the first definitively experimental psychological laboratory in 1879 as well as to train-up the first generation of German and American "experimental" psychologists. Wundt also remained active in the ensuing disciplinary debates right up to his death in 1920.

In this subsection, we will emphasize three aspects of this initial formulation of psychological science: (1) the methodological structure of Wundt's system of psychology (including his successive demarcations between experimental physiological versus "folk psychology"); (2) the circumscribed content of experimental research carried out in the Leipzig laboratory (on sensation, perception, reaction time, attention, feeling); and (3) the eventual disciplinary challenge presented by Külpe and Titchener regarding the issue of the status of higher mental processes.

Wilhelm Wundt (1832-1920)

Born in Baden (a suburb of Mannheim, Germany), where his father was a Lutheran pastor, Wilhelm received a private education from a vicar-friend of the family until age 13 when he began attending public Gymnasium schools at Bruschal and Heidelberg. His initial university studies (beginning in 1851 at Tubingen followed by 3.5 years at Heidelberg) were embarked upon with the intent of becoming an experimental physiologist. When his father passed away, however, Wundt was counseled for pragmatic reasons to pursue a medical degree.

After receiving two years of medical training at Heidelberg, as well as doing a 3rd-year medical clinic practicum, Wundt revived his earlier experimental-academic interests by slipping off to Berlin for a semester (of the 1856 term) at Johannes Müller's institute of physiology before returning to Heidelberg for the obligatory completion of his doctorate in medicine.

Between 1857-1864, Wundt made ends meet by serving as a Dozent, guiding Heidelberg students through the physiological practicum component of their medical degrees. The primary notable written product of this early formative period (from our perspective) was Wundt's book on the theory of perception (Beiträge zur Theorie der Sinneswahrnehmung, [Contributions to the Theory of Sensory Perception], 1858-1861). That work not only drew upon the physiological work of E.H. Weber, J. Müller and Lotze; but also included a direct call for the development of an "experimental psychology" (thereby foreshadowing later developments).

In the fall of 1858 too, Helmholtz came from Bonn to Heidelberg. Wundt (11 years his junior) was immediately appointed assistant to Helmholtz and held this position for 13 years until 1871 (when Helmholtz left for Berlin). Although Wundt did not receive the vacancy left open by Helmholtz, he stayed on at Heidelberg to lecture on experimental physiology and medical physics until 1874.

During these "formative" Heidelberg years, Wundt was clearly shifting away from physiology and toward psychology as a potentially viable career path. As Fancher (1990) outlines quite nicely, it was in 1861 that Wundt rigged up the first primitive "thought meter" from a pendulum clock and started advocating mental chronometry of central psychological processes as a possible answer to the old astronomer's problem of differential judgments regarding the transit of stars. Similarly, at Heidelberg in 1862, Wundt began presenting a course of lectures initially called "psychology from the standpoint of the natural sciences," changing the title to "physiological psychology" in 1867. By then he was already running a privately funded (out of pocket) laboratory in Heidelberg, 1865-1874 (see Bringman, et al., 1997). Most notably, however, it was during the Heidelberg period that Wundt wrote up his Principles of Physiological Psychology which originally appeared in two volumes (1873-74). This latter work was a drawing together of prior physiological, psychophysical and reaction time research which served as "the first constitution for psychology as an independent science" (Heidbreder, 1933, p. 93).

In 1874, Wundt took up a one year appointment in inductive philosophy at Zürich before moving on to Leipzig under the stipulation that he would be provided with storage space for his experimental apparatus. In this sense, the fundamental material technology and intellectual aspects of his "system of psychology," which was then constantly revised and augmented throughout his subsequent career preceded the move to Leipzig. Wundt remaining at Leipzig, however, to both found and slowly expand the now famous psychological laboratory from 1879 onwards.

This was the manner in which Wilhelm Wundt became the first figure we have covered whom can unequivocally be called a "psychologist." The systematic outline contained in his successive writings (including the Groundwork of Psychology, 1896; later translated to English as Outlines of Psychology); the founding of the first empirically productive "psychological" laboratory; and his eventual overseeing of 200 odd student theses, all had profound effects on the future development of the discipline.

Wundt's system and the Founding of a Discipline

Wundt exemplifies a kind of disciplinary turning point from philosophical and physiological research toward the founding of a stand-alone psychological science. In the preface to the first part of his Physiological Psychology (1873), for instance, he had clearly separated himself off from: British empiricism in that he was explicitly seeking to accomplish a "reform" of the former philosophically guided tradition of psychological investigation by way of "the introduction of the experimental method"; and from the German physiological tradition in that he was outlining a method of investigating "conscious processes" and the "modes of connection particular to them" rather than their "bodily substrates" per se.

Wundt was now embarking upon a 35 year program of research at Leipzig which would also separate his initial late 19th century formulation of psychology from what came afterward in the early 20th century American context. So, let's take some time to understand the fundamental systematic aspects of his initial formulation of psychology including: (1) his successive demarcations between experimental physiological versus "folk psychology"; and (2) the circumscribed content of experimental research carried out in the Leipzig laboratory.

Systematic aspects

Wundt's Physiological Psychology (1873-4), was a formal attempt to work out a new domain of science and would undergo six expansive editions (up to 1911) as the program of research at Leipzig pressed forward. Our primary concern with regard to the systematic aspects of Wundt's initial account is why he called it "physiological" psychology. He called it "physiological" because it would use the available empirical methods of physiological science to study conscious process. These methods, he argued, would render "the same help to psychology as it had itself received from physics" and further, in as much as this new domain of research "receives assistance from physiology in the elaboration of experimental methods, it may be termed experimental psychology..." (Wundt, 1873, preface).

Before preceding on with a substantive account of the research carried out in the Leipzig laboratory, however, we must deal (as Wundt was forced to do) with the somewhat thorny methodological issues of: (i) the nature of "scientific" psychological introspection; (ii) his understanding of the "content" of consciousness; and (iii) the resulting limits of the applicability of experimental method (which for him had to be augmented by other methods of inquiry).

On "scientific" introspection, experimentation, and conscious contents

First of all, it must be mentioned that Wundt started out by accepting the Kantian (and then Comtean) criticism of simplistic introspective analysis of mental events. These criticisms sprang from their common acceptance of the enrichment theory of perception and argued that the isolated individual mind could not, therefore, observe itself without changing its own content. "Pure" introspective analysis as they understood it could never be scientifically measurable in the quantitative sense of the word.

By way of drawing upon the arguments of both Herbart who had suggested that psychology could be quantitative and Fechner who had already carried out various experiments along the psychophysical line of inquiry, however, Wundt counter-argued. He suggested there are special circumstances under which such general criticisms do not hold. These special circumstances could be realized in the psychological laboratory in which "scientific introspection" can be carried out:

"It is only with grave reservations that what is called 'pure self-observation' can properly be termed observation at all, and under no circumstances can it lay claim to accuracy. On the other hand, it is of the essence of experiment that we can vary the conditions of an occurrence at will and, if we are aiming at exact results, in a quantitatively determinable way.... it alone makes a scientific introspection [of conscious contents] possible" (Wundt, 1873, preface).

As Boring (1950) notes, even from the time of appending the general introduction to his Beiträge (1862), for Wundt (as it was with Fechner) scientific meant experimental. Wundt (1873) was now bringing his initial call for experimental psychology one step closer to reality by proposing that we use the controlled conditions of the laboratory to make our fleeting awareness of so-called inner experience of "conscious content" (that which he saw as the psychological aspect of Fechnerian experimentation) out into the open.

For Wundt, creating a scientific psychology meant finding ways to objectify mental events (to make them public) by forcing them to approximate so-called outer experiences which are more stable. This could be done by limiting the scope of experimental study to those experiences evoked by external stimulation by exposure to reaction-time apparatus, controlled sensory displays, and/or visual or verbally presented word combinations of known complexity.

The experimental situation, as envisioned by Wundt (1873), would thus not only determine the kinds of mental events to be reported upon by an "observer," it would thus hold them still long enough to be reported upon as well:

"The endeavor to observe oneself must inevitably introduce changes into the course of mental events, .... and [the] consequence is that the very process which was to have been observed disappears from consciousness. The psychological experiment proceeds very differently. In the first place, it creates external conditions that look towards the production of a determinate mental process at a given moment. In the second place, it makes the observer so far master of the general situation, that the state of consciousness accompanying this process remains approximately unchanged" (Wundt, 1873, preface).

Under these controlled conditions, descriptive reports of individual psychological experience ("states of consciousness") as analyzed into their (Sensory, Ideational, and/or Affective) "associational" elements or complexes; and/or "apperceptive" judgments or concepts (depending upon both how sophisticated that external stimulation was and how far they are brought into the "focus" of consciousness) comprised the subject matter of the Wundtian program of experimental research (in its matured 1893 onward form). Further, it was suggested (from the beginning) that carefully structured empirical measurement using the subtractive technique of Donders could also outline the duration of such central psychological processes (much as Helmholtz had done for the speed of peripheral nerve impulses).

We will cover shortly how the above encapsulation of the experimental aspects of inquiry both guided the structure of and was adjusted according to the results obtained in the research of the Leipzig laboratory (including the respective speed of peripheral versus sensory reaction times), but one other crucial aspect of Wundt's constantly expanding systematic outline of psychology must be mentioned before proceeding: his "Volkerpsychologie" (folk psychology) which was cultural-historical rather than experimental.

Wundt's non-experimental aspect of psychology

As far as the subject matter (the normal individual human mind) of his experimental psychology is concerned , Wundt was quite conservative. The empirical program for experimental psychology involving both scientific introspection and measurements of the duration of individual psychological experience, though innovative, was also explicitly outlined (in Wundt, 1873) as pertaining only to a circumscribed set of elementary processes (including sensation, perception, reaction time) and was subsequently expanded to "attentional and feeling aspects" of mental associations and apperceptions.

While the adoption of experimental methods would provide a foothold for the discipline, the ultimate aim and results of such basic research, (as stated by Wundt, 1873), must eventually be applied to "other mental phenomena," (higher mental processes) which were not directly studyable by way of experimental manipulation due to their collective cultural-historical nature. These "complex mental processes," must be 'got at' by the careful observational study of the history of human nature which he called variously "ethnic" and "Volkerpsychologie".

The disciplinary function of this wider "department" of psychological inquiry was to both augment and inform the narrower concerns of the experimental aspect of the discipline. These "two principal departments" of psychological inquiry were to be "supplemented" by other specialized branches of inquiry as well:

"We may add that, fortunately for the science, there are other sources of objective psychological knowledge, which become accessible at the very point where the experimental method fails us. These are certain products of the common mental life,... chief among them are language, myth and custom. In part determined by historical conditions, they are also, in part, dependent upon universal psychological laws, and ... form the subject-matter of ... ethnic psychology. [Their results] ... constitute... our chief source of information regarding... complex mental processes. In this way, experimental... and ethnic psychology form the two principal departments of scientific psychology at large. They are supplemented by child and animal psychology.... Finally, ... animal... and ethnic psychology form the two halves of a generic or comparative psychology.... [E]thnic psychology, must always come to the assistance of individual [child and experimental] psychology, when the developmental forms of the complex mental processes are in question" (Wundt , 1873, preface).

So, from the very beginning, a methodological dichotomy was set up by Wundt between experimental laboratory psychology (an individual affair which held inherently dynamic mental content still enough to be measured), and other proposed sources or methods of wider psychological inquiry (which were observational, developmental, cultural-dynamic, and collective). Thus, child and animal psychology (in conjunction with ethnic psychology) "attempt to resolve the problems of psychogenesis" but experimental psychology attempts to hold mental processes still so that they can be observed as static mental states.

Clearly, Wundt's original intent was that these "two principal departments" as well as the "supplemental" branches should inform each other. He would later attempt to exemplify this disciplinary ideal too; rounding out the above system through the successive publication of his ten-volume tome Volkerpsychologie (1900-20). The first volume of that work, in particular has been noted for its progressive treatment of language and for expressing the view that mental differences among the peoples of the world are culturally determined (Blumenthal, 1970; 1997).

Investigation of higher mental processes including what came to be called thinking or cognition, emotion, and motivation must proceed, according to Wundt, from the assumption that they are determined by culture. This notion of cultural determination directly influenced both Franz Boas (then a young anthropology student in attendance at Wundt's lectures) as well as Emile Durkheim (the influential sociologist to be), who also studied with Wundt on these topics. Such a view was, however, at odds with the opinions held by many contemporaneous intellectuals who saw mental differences among societies as racially based (Brock, 1992; Jahoda, 1997).

In practice then, experimental and ethnic-cultural studies initially proceeded along parallel lines. The eventual result of the original methodological dichotomy was that some figures concentrated on the former experimental aspect of Wundt's program and became known as psychologists while other figures concentrated on the latter aspect and became sociologists or anthropologists.

Along the way, Wundt (in the 4th edition of his Principles of Physiological Psychology, 1893) attempted to elevate the initially supplemental status of Volkerpsychologie to one of equality with experimentation. By the turn of the century, however, he was lamenting the emphasis upon laboratory apparatus which was beginning to dominate American psychology -referring to the new breed of apparatus men as "mere technicians" having a very constricted vision of the greater goals and potential of the science as a whole (Blumenthal, 1997; see also Wundt, Elements of Folk Psychology, 1912). But before there was any hint of lamentation, there was an exciting era of institutional expansion and carrying out of basic empirical research in the Leipzig laboratory. So it is to these developments that we now turn.

Expansion and Research of the Leipzig Laboratory (1879-1920)

Upon arriving at Leipzig in the fall of 1875 to assume his teaching duties in the philosophy department, Wundt was initially allotted a mere storage space for the purposes of demonstrating experimental apparatus "in connection with his lectures" (see Boring, 1950; Bringmann et al., 1997). In other words, despite having already worked out a rather weighty outline of experimental-psychological science in considerable detail, Wundt was now faced with the task of building up the institutional standing and auspices of a functioning laboratory in stages over time.

The psychological laboratory activities and facilities at Leipzig evolved gradually from informal bull sessions between Wundt and some of his earliest students (following class lectures); to the carrying out of research practica or student projects (assigned by Wundt); and only then to the running of an officially recognized psychological research institute with subdirectors reporting to Wundt (Bringmann et al., 1997; Blumenthal, 1997). Three distinct cohorts of students can also be noted as being produced during this three-step process of institutional expansion with Oswald Külpe (whose stay was the longest) serving as either a personal or theoretical 'bridging figure' between all three.

The first psychology lab at Leipzig (1879-1892)

The first step in this expansive direction came in 1879 when, without ceremony, Wundt moved his experimental apparatus to a room in the cafeteria building (shown right) with the operational expenses being funded until 1881 out of his own pocket.

The initial study originating from this seminar-practicum stage of the laboratory was that of Max Friedrich's doctoral research published under the title "On the Duration of Apperception for Simple and Complex Visual Stimuli" in the first volume of Wundt's own journal, Philosophical Studies (1883). This journal functioned as the primary publication vehicle for the lab between 1883-1903.

Friedrich found that "apperception" times decreased over the course of experiments, and that this decrease was more marked for "complex" relative to simple visually presented stimuli. There was, for instance, a greater decrease in reaction times across trials to presented numbers, than to colors. The issue was thus raised how far the respective reaction times could be reduced with practice and what psychological laws might govern the respective decreases.

During G. Stanley Hall's postdoctoral stay at Leipzig (from the winter term of 1879 through to the following summer term), he participated (along with Wundt, Friedrich, and another student Ernst Tischer) as one of the four subjects in Friedrich's study. What most impressed Hall, however, was not the laboratory itself but Wundt's lectures on folk psychology which contained an account of the cultural-historical aspects of the discipline.

While it is Friedrich who best exemplifies the kind of German student which Wundt (1873) probably had in mind for the pursuit of the experimental aspects of the discipline (see Behrens, 1997), it must also be noted that by 1880, Hermann Ebbinghaus an outsider to the lab who was then serving as an untenured instructor at Berlin had already carried out his experimental work on "memory" (a higher mental process) and was now repeating various aspects of this initial (1878-1879) research in preparation for publication (Lander, 1997). The eventual appearance of the resulting monograph On Memory (Ebbinghaus, 1885) constituted the initial disciplinary challenge to Wundt's institution-building efforts at Leipzig because by utilizing a simple and inexpensive empirical technique (the retention of nonsense syllables), Ebbinghaus had seemingly proved Wundt wrong regarding the measurability of higher mental processes just as his apparatus-intensive laboratory was getting off the ground. However, Wundt's definition of collective higher mental processes (such as memory, language, etc.) went well beyond the bounds of the individual physiological retention studied by Ebbinghaus. We will return to this rather fundamental point periodically, but for now we should simply note this theoretical difference as one reason why Wundt didn't simply 'close up shop' at that point in time.

After Hall, another American, James McKeen Cattell came to Leipzig to carry out doctoral research under Wundt (from 1883 to 1886). While there, Cattell built both a "gravity chronometer" apparatus (utilized to present and time reactions to visual stimuli) as well as a "lip-key" apparatus which (upon movement of the lips) functioned like the "finger-key" of prior studies to turn off the chronometer. The empirical results of Cattell's varied investigations were published in the British journal Mind -founded by Alexander Bain in 1876- under the collective title: "The time taken up by Cerebral Operations" (1886).

Two aspects of Cattell's research at Leipzig are notable as indicating similarity and divergence between Cattell and Wundt:

First of all, finding that reaction times for the visually presented short words were only negligibly longer than for individual letters, Cattell concluded that we "do not... perceive separately the letters of which a word is composed, but the word as a whole" (see also Fancher, 1990, pp. 159-161). This aspect of his analysis falls within Wundt's view of "creative synthesis" (which states that some psychical resultants are not reducible to the lower elements from which they are produced but possess their own properties) in the fashion of the mental chemistry originally proposed by J.S. Mill.

Secondly, Cattell (1886) observed individual differences -between himself and the other student serving as subject- on their respective reaction times for "verbal association" tasks (such as replying to a German word with its English translation; or naming the country in which a presented city name resides). The manner by which Cattell interpreted these results, however, indicates an important divergence from the Wundtian program of experimental psychology and preludes Cattell's later promotion of "mental tests" (at Penn and Columbia). More specifically, although the reaction time structure of the research itself (and even the notation of individual differences of performance) bears some relation to the initial (1861) "mental chronometry" research which launched Wundt's professional career toward psychology, Cattell's (1886) suggestion that such particular performance differences (on reaction time tasks) might be somehow representative of more general intellectual differences between people digressed considerably from Wundt's cultural-historical views on higher intellect.

As Boring (1950) points out, Wundt explicitly distanced himself from Cattell's interpretation of such results by calling it the "ganz Amerikanisch" [literally: 'all American'; but figuratively: the 'wholly American idea, issue, or problem'] (see also Cattell, 1928 where he lets it slip that he already had this intellectual differences hypothesis in mind prior to starting his Leipzig research). In any case, the ensuing so-called "mental" and "intelligence" testing movement in America, as well as the rise of the college-entrance exam tradition, would remained an ongoing problem even long after Cattell's anthropometric approach to it (which he borrowed from Francis Galton, a Brit) was empirically discounted and abandoned (see Ballantyne, 2002).

Also instructive with regard to gaining an understanding of the early phase of the Leipzig laboratory is the arrival in 1884 of a third American, Harry Kirke Wolfe, who had previously come under the influence of Ebbinghaus at Berlin but then completed an 1886 doctorate under Wundt on "memory for tones" (see Benjamin, 1991; 1997). This was an unusual topic for a Wundtian student but one that might also reflect the practicalities of the institution-building motives of Wundt himself; for an experimental study of retention under any other name would smell as sweat when it came to forwarding the disciplinary status of the laboratory.

It was a German, Ludwig Lange, however, whose 1888 study marked a definative shift away from reaction time studies at Leipzig toward the study of "attention" (which characterizes the upper bounds of the experimental method according to Wundt's outline). Lange compared "simple" reaction times (with one presented stimulus and one required physical response) obtained under two experimental conditions: (i) when a subject's attention was focused on the expected stimulus (called sensory reaction time); and (ii) when the subject's attention was focused on the response to be made (called muscular reaction time). That is, in one experimental condition the subject focused on what he was about to see, and in the other to what he was about to do. Reaction times in the first case were found to be about 1/10th of a second longer than those in the second case.

The discovery that such "muscular" reaction times were generally 1/10 of a second less than sensory reaction times was taken to mean that the latter involved time of apperception of a sensory impression while the former did not. In interpreting these results, it was Wundt who borrowed Leibniz's distinction between sensory perception and "apperception" with the former being portrayed as automatic and the latter requiring one's full attention to be focused.

Aspect of mindMechanismExamples
ApperceptionActive attention judgments, ideas, concepts
Sensory AssociationPassive, automaticsensory fusion, assimilation, complications

The actual contemporaneous breakdown between 'passive sensory association' and 'active apperception' (as shown above) doesn't matter as much to us as simply noting that the overall methodological approach being attempted is an anti-reductive one running along the lines of mental chemistry (al la J.S. Mill) rather than the agglomerative conjunction of James Mill. Wundt believed "apperception" to be a relatively more complex psychic resultant which contained an active 'cognitive' property (judgments, ideas, concepts) produced by way of a "creative synthesis" of constituent elements. Simply stated, "apperception" contains properties of conscious content which went beyond the bounds of mere sensory-perceptual associations.

Thus Wundt (1896; 1911 respectively) utilized the examples of tonal clangs and metronome beats to illustrate this anti-reductive point. A single recurring beat (produced by a metronome or other laboratory apparatus) constitutes "a sensation," but the combination of two or more beats combine and constitute an "idea." Similarly, a single clang (produced by the striking of a metal object or by a musical instrument) is a "psychic element" but simultaneous clangs can sometimes produce musical "chords," which although they can be analytically broken down into harmonics, constitute (phenomenologically speaking) a larger unit (a "psychic compound") for the listener (see the Wundt extracts contained in R.I. Watson, 1979, pp. 132-136).

"A compound clang is more in its ideational and affective attributes than merely a sum of single tones. In spatial and temporal ideas the spatial and temporal arrangement is conditioned, to be sure, in a perfectly regular way by the cooperation of the elements that make up the idea, but still the arrangement itself can by no means be regarded as a property belonging to the sensational elements themselves. The nativistic theories that assume this, implicate themselves in contradictions... they are ultimately driven to the [recognition] of the rise, to some extent at least, of new attributes. Finally, ... the aggregate idea itself is a new psychical content that was made possible, to be sure, by these elements, but was by no means contained in them. This appears most strikingly in the more complex productions of apperceptive synthesis, as, for example, in a work of art or a train of logical thought.... The law of psychical resultants thus expresses a principle which we may designate, in view of its results, as a principle of creative synthesis. This has long been recognized in the case of higher mental creations, but generally not applied to the other [lower] psychical processes" (Wundt, 1896/1907, Outlines of Psychology, Sect. 23).

Given that Wundt believed (from the mid-1880s onward) that psychic resultants of this 'lower' "apperceptive" sort could be investigated experimentally, various studies on the "span of apperception" (how many presented stimuli could be attended to simultaneously) were forthcoming. It was found that when an array of random letters was flashed, subjects typically recalled 4-6 of them. Similarly, if the array was comprised of words (of six or less letters) 4-6 of those were also picked up by the subjects. The span of apperception, therefore was established experimentally, and these findings corroborated Cattell's two earlier findings (that familiar words could be reacted to as quickly as individual letters and that they could be treated as wholes rather than additive collections of individual letters).

Boring (1950) names Dietze (1884) on the "range of auditory attention," as well as Tchisch, Pflaum, and Geiger (working from 1886-1902) in this regard. Experimental work of this sort, therefore, continued through the second and third expansive stages of the laboratory (1892 and 1897 respectively).

Wundt and Külpe versus Titchener on psychological methodology

In the years just prior to the second laboratory expansion, Wundt believed that he had already extended the reaches of the experimental method as far as it was applicable. He gradually began withdrawing from the day to day running of experiments, redirecting his energies successively toward preparing for the further institutional expansion of facilities and the writing of a formal elaboration of his Volkerpsychologie.

Oswald Külpe (who arrived in 1886 after having spent three semesters at Göttingen working on his dissertation under Georg Elias Müller), received a doctorate under Wundt in 1887, and was selected from the remaining first stage cohort of students to oversee the activities of the laboratory (a posting he retained from 1887-1894 when he left for Würzburg to found his own school). Edward B. Titchener (an Englishman initially trained at Oxford in a blend of British associationism and biology), was also there during the last two years of the initial Leipzig lab carrying out research on "The chronometry of the act of recognition" between 1890-1892 (published as Zur Chronometrie des Erkennungsactes, Philosophische Studien, 1893, 8, 138-144).

While these two latter individuals maintained a cordial personal as well as a professional relationship thereafter, the work being carried out in the lab at the time was as Boring (1950) states, showing that the differences between 'sensory and muscular' reaction times "is to be laid at the door of... predisposing attention" (p. 342). This evidence, while exciting, eventually produced a three-way methodological splitbetween Wundt, Külpe, and Titchener which is important to mention.

ProponentView of Conscious ContentHigher Mental Processes (method of study)
Wundt (1874; 1896)mostly elemental but some psychical resultants (like attention)Volkerpsychologie
Külpe (1893; 1912) non-elemental (including meaning, set, and intentions)experimental
Titchener (1896; 1901-1905; 1909; 1910) elements and attributes ('meaning' is at worst a "stimulus error" and at best a "context" of unconscious elements)experimental reduction

Wundt interpreted the work on attention as reflective of the "principle of psychical resultants" and considered the experimental methods used on this highest reach of "conscious content" as not to be extendable to higher mental processes; which required their own branch of psychology utilizing comparative, historical, non-experimental methods. As he defined them, the higher mental processes could not be studied by looking at conscious contents (imaginal, sensory, and affectional elements or resultants) alone.

While Külpe concurred with Wundt's anti-reductive approach to attention as a psychical resultant, he argued that experimental methods could be extended further. His successive research programs at Würzburg (1894-1909) and then Bonn (1909 onward) would help Külpe refine this methodological divergence from Wundt's original outline more fully, but divergence on the fundamental methodological point of experimentation was already in evidence prior to Külpe's departure from Leipzig. In 1893, for instance, his Grundriss der Psychologie appeared. Although dedicated to Wundt, it contains a rather bold assertion too:

"In principle there is no topic of psychological inquiry which cannot be approached by the experimental method. And experimental psychology is, therefore, fully within its rights when it claims to be... general psychology" (Külpe, 1893; translated by Titchener as Outlines of Psychology; Külpe, 1895).

In the succeeding years, Külpe remained in agreement with Wundt regarding the irreducibility of higher mental processes but refined his argument by suggested that they are part of conscious content broadly defined to include "determining tendencies" like attention, mental set, and intentions. The divergence between Wundt and Külpe is one of how far to push experimental methods and how seriously to take the "new properties" (psychical resultants) present in such processes as attention, thought, meaning, language, etc.

In Titchener, we get a third methodological position which is markedly reductive and more static than either of the other two. He agrees with Külpe that higher mental processes are part of conscious contents and that they can be studied by way of experiment, but defines the structure of such content more conservatively than even Wundt's (1880s onward) 'elements or psychical resultants' position. Titchener's definition of conscious content seems to have been arrested at a reductive interpretation of the attention research being carried out at Leipzig when he left that initial laboratory setting. Titchener would stand almost alone in his continuing commitment to Wundt's 1860s-70s additive-conglomeration view of so-called psychical resultants (which Wundt had initially borrowed from British associationism but which Wundt gave up later on).

According to Titchener (1908, 1909; 1910) 'attention' and so-called 'imageless' thought (as well as the 'determining tendencies, sets, and meanings' later studied by Külpe's students) could all be reduced (if carefully reflected upon by way of experimental introspection) to contentual elements of images, sensations, and affections. In this respect his views on psychology reflect both a conservative drive for simplicity (regarding the number of mental elements to be brought into the discipline) and the primarily British associationist background of his initial education (see R.I. Watson & Evans, 1991; Tweney, 1997). His principle of elemental combination (that of "accrual") does not go beyond the additive model of James Mill's classical views on association of ideas.

In his "context theory" of meaning, for instance, a theory which Titchener (1909) put forward as part of the 'imageless thought controversy' (between himself and the Würzburg school), both of the above italicized aspects of his methodological approach are in evidence. "Meaning," for him, is merely an additive (accruing) context of either conscious or unconsciously held (inadequately reflected) sensory-imaginal elements and their attributes:

"My mind... is of the imaginal sort, -I wish that we had a better adjective!- and my ideational type is of the sort described in the psychologies as mixed. I have always had, and I have always used, a wide range and great variety of imagery; and my furniture of images is, perhaps, in better than average condition because.... I have made a point of renewing it by practice.... Whenever I read or hear that somebody has done something modestly, or gravely, or proudly, or humbly, or courteously, I see a visual hint of the modesty or gravity or pride or humility.... A great many of these [visual] sketches are irrelevant and accessory; but they often are, and they always may be, the vehicles of a logical meaning.... I hold that, from the psychological... point of view, meaning -so far as it finds representation in consciousness at all- is always context.... And I understand by context simply the mental process or complex of mental processes which accrues to the original idea through the situation in which the organism finds itself -primitively, the natural [object-oriented] situation; later, either the natural or the mental.... My task has been to persuade you that there is no need,... to swell the number of the mental elements; that the psychology of thought, so far as we have it, may be interpreted from the sensationalistic standpoint" (Titchener, Lectures on the experimental psychology of the thought-processes, 1909).

The following passage from Boring (himself a Titchener student) summarizes the relevant contrast between Titchener's context theory and Külpe's imageless-thought school of meaning quite nicely:

"Titchener's interest in thought was conditioned upon the work of the Würzburg school. He took his stand for the sensory and imaginal nature of the thought-processes. He opposed the belief in imageless thought and argued that, because some thought-processes resist analysis, that fact does not mean that they are not actually sensory-imaginal patterns. Thus at Cornell the 'conscious attitude' came to mean a pattern of the older mental elements.... In Thought-Processes [1909] he put forth his context theory of meaning, which makes meaning the conscious sensory or imaginal context that accrues (associatively, it would seem) to the initial sensory core of a perception or the initial imaginal core of an idea. However, this law of meaning holds [is introspectively evident], he thought, only for new perceptions and ideas; in old habituated ones the core [typically] occurs without conscious [awareness] and the meaning is 'carried unconsciously.' It was in this way that he sought to explain the paucity [scarcity] of conscious [imaginal] content in thought at Würzburg" (Boring, 1950, pp. 415-416).

Külpe's position was nonreductive and emergent. His Würzburg school was an assertion of the possibility of replacing a purely elemental understanding of thought-processes. Meaning (as in the case of verbal reasoning tasks) is there and it is often not reducible to mere elements contained in presented stimuli, nor to imaginal (visual) elements produced in an experimental subject. When one is asked to assess the meaning of an ambiguous verbal statement (e.g., "Thinking is so extraordinarily difficult that many prefer to judge") some sort of determining tendencies (toward one assessment or another) need to be referred to, and although these tendencies do not reside per se in the statement itself (the presented stimulus) but in the assessment produced by the subject, they can (under controlled conditions) be investigated by way of experiment. Similarly, if one is asked to recall a poem, the individual words or mental images aroused by these may be forgotten but the meaningful content can be stated anyway (see Külpe, 1912).

Wundt's methodology was nonreductive too. Both psychical resultants (like attention) and higher mental processes (like the meaningful thought-processes studied by the Würzburg school) are there, and they are not reducible to elements. Higher mental processes, in particular, must be sought outside conscious content (as defined by him) altogether.

Titchener's methodological position, however, is completely reductive. Higher mental processes are these elements and their attributes. He carries out a direct translation of the methodological assumptions of late 19th century positivism (the "Empirio-Criticism" of Mach and Avenarius) to psychology. Therefore, we see a Humean epistemology (e.g., Titchener's equation of image with idea and denial of "imageless" thought). We also see an eschewing of anything deemed to be "metaphysical" or "teleological" -including any reference to 'functions, intentions, mental acts, or commonsense meanings' (the latter of which Titchener viewed as a "stimulus error"). His psychology is a methodological elementism which imposes a complete reduction of all higher processes to 3 "elements" (sensations as elements of perception; images as elements of ideas; and affections as elements of emotion) and 4 "attributes" (quality, intensity, duration, and clearness).

In her coverage of Titchener, Heidbreder (1933) touches on some of these points by outlining his reductive methodology and its application to the "problem of attention" as follows:

"Out of these elements -sensation, image, and affection- is made the whole structure of the psychic life.... the fundamental assumption is that in some way the more complex states of consciousness are always made up of elementary processes, that different combinations of elements.... [sometimes blend]... But always the more complex states are in some sense compositions of the elements; and the task of psychology is to show how the [so-called] higher mental processes can be accounted for in this way....

At the threshold of this task lies the problem of attention. Titchener's [1901-1905; 1910] treatment of this problem is strongly characteristic, revealing as it does the distinctively 'structural' features of his psychology. In attention, [as] in any mental process, there [may seem] to be something actually working, [such as a prescientific active power or 'faculty of attention']. But there is no place in Titchener's psychology for 'powers' and 'faculties' nor, ... for the 'acts' and 'functions' of rival contemporary schools. In his hands, even attention becomes a matter of content; and [experimental] introspection is consulted... to discover its [arrangement].... In the state of attention, consciousness falls into focus and margin, the... difference between the two being a difference in clearness. Attention, then, is essentially clearness, .... a patterning of consciousness [rather than a power or act]" (Heidbreder, 1933, pp. 138-139).

Despite all its talk of mental "processes," Titchener's system was passive, static, mechanical, and anti-applied to the extreme. We will pick up on this theme in Section 4 by contrasting Titchener's "structural" psychology more fully with the "functional" psychology founded by William James but suffice it to say that all the active processes referred to in Külpe's work (attending, meaning, intending, thinking, etc.) become passive states of structural content in Titchener. Attention, for instance, is not portrayed as 'something you do' but as 'something which happens to you.'

Subsequent expansions and interests (The Psychology Institute)

While Titchener left for America in 1892 (bringing his elemental methodology to Cornell along with him), Külpe stayed on at Leipzig for a time to both continue lecturing as an untenured professor and to oversee the next expansive stage of the laboratory. Külpe, therefore, was the functional head of the lab both prior to and after its second (1892) move to the third floor of the main Leipzig classroom building (shown right).

This second facility (which had previously housed the department of gynecology) now provided 11 work rooms all equipped with electrical connections. These were valuable not only for the operation of existing laboratory apparatus but also for advancing the material technology of the trade (Bringmann et al., 1997; Blumenthal, 1997). In this regard Wundt's own description of the development of "The Institute" to 1909 (Transl. by Murray, et al., 2002) highlights the successive efforts of the Leipzig laboratory technicians (K. Krille in the first two facilities; and E. Zimmermann in the third); as well as touching upon the subsequent refinements and inventions made by Wilhelm Wirth -student, lab assistant, and eventual codirector (see also Schroder, 1997; Gundlach, 1997).

After Külpe's 1894 departure, there was a third expansion of facilities which was connected with a wider rebuilding effort at Leipzig University. In the fall of 1897, Wundt's institute was moved to the top floor of two new buildings (Paulinum and Johanneum), which had been designed to his specifications and which served as a model for similar laboratories in Germany and abroad. Wundt (1909) provides a detailed floor plan and description of this new facility as well as an account of its funding arrangements and teaching versus research roles.

A considerably older looking Wundt is shown (right) demonstrating a 'choice reaction time set up' and accompanied by contemporaneous figures from this third institutional setting (Ca. 1910). From left to right: M. Dittrich, W. Wirth, W. Wundt, O. Klemm, and F. Sander (Bringmann & Tweney, 1980).

Both Wundt's (1909) report on the institute, and Boring's (1929; 1950) assessment concur that research carried out in the laboratory began predominantly with sensation and perception (including 'time sense'); shifted to include reaction time and attention (mid-1880s); and only then moved onto consideration of topics like memory (e.g., see Wirth's "Memory apparatus"), volition, and feelings (the latter of which Boring reports as an entirely 1890s onward affair).

While no mention of "Volkerpsychologie" is made in Wundt's (1909) account, Blumenthal (1997) reports that:

"By the onset of W.W.I, Wundt's facilities at Leipzig had grown into a multistoried institute with subdivisions for cultural psychology, psychophysics, developmental psychology, psycholinguistics, and more; each under the leadership of a subdirector who reported to Wundt. But... this grandest moment, [was] on the eve of a great decline [in Germany] caused by war, then economic chaos, then Hitler, and the World War II bombing raids that destroyed it" (Blumenthal, 1997).

If by the above term "grandest moment," Blumenthal means the full fruition of Wundt's institutional strivings at Leipzig, then this is all well and good. However, from the perspective of early through mid 20th century "general-experimental" subject matter in psychology, it was Külpe's Würzburg school (not Wundt's institute) that best succeeded in addressing the issues of higher thought-processes. To do this work, they had to break free of the restrictive prescripts of Wundt's system (even during its latter relatively more inclusive stage).

Külpe versus Wundt: Thought-processes, experimental tasks, and subject-experimenter relations.

Oswald Külpe (1862-1915) -shown right- produced a summary statement of the way things stood (both methodologically and theoretically) in 1912 which is very informative. The "New psychology" of Wundt's institute was "so busy bringing order [to]... sensations, images and feelings," that it was "quite late" before anyone in Germany began addressing "airy thoughts." When they did, the concepts of association psychology including mental chemistry failed to come up with anything more than a "descriptive" analysis, and even ruled out consideration of certain aspects of the experimental situation which Külpe found to be of vital importance including the tasks being carried out by subjects. Subsequent analysis of the Külpe versus Wundt divide have also emphasized the differential social-power relations between subject and experimenter in the two respective institutes.

"The first mental contents to be noted in consciousness [by Weber, Fechner, and Helmholtz] were those of pressures and punctures, tastes and smells, sounds and colors.... That there was anything else without the palpable constitution of these formations escaped the eye of the scientist who had not been trained to perceive it. [In Wundt's laboratory:] The... researcher's attention [was directed] toward sensory stimuli and sensations, afterimages, [or] contrast phenomena.... Furthermore, [in Titchener and Wundt's institute] the commitment to the traditional concepts of sensations, feelings, and images prevented the observation or labeling of that which was neither sensation nor feeling nor image. However, as soon as persons trained in self-observation [the Würzburgers] were allowed to make complete and unprejudiced reports about their experiences of an experiment... [along the intentional lines of Brentano] the necessity for an extension of the previous concepts and definitions became obvious. We found in ourselves processes, states, directions, and acts which did not fit the schema of the older psychology. Subjects started to speak in the language of everyday life and to give images only a subordinate importance in their private world. They knew and thought, judged and understood, apprehended meaning and interpreted connections..." (Külpe, 1912).

Under Külpe's direction the Würzburg institute published some 50 experimental studies before his departure for the University of Bonn in 1909. Studies indicative of this newer kind of research include those by Karl Marbe (1901); Narziss Ach (1905); and Karl Bühler (1907). For an account of how the intentional ('Act psychology') content, and assumed social roles of 'experimenter and subject' in those respective studies were a break with the Wundtian tradition (see: Kleining, et al. "Roles of Researchers in Introspective Psychology"); and for an albeit brief sketch of how they collectively compare with later roles assumed in American applied and behavioral psychology (see Table 1 in Ballantyne, 1996). It should suffice for our present purposes, however, to return to Külpe's (1912) summary:

"Although one once could ... construct a mosaic... of the coming and going of conscious elements, such a simplification and dependence upon chemical analogies has now lost its footing.... Just as perception could not be characterized as a mere having of sensation, no less could thinking be conceived as the associative course of images. Association psychology, as it had been founded by Hume, lost its hegemony.... [Now] thoughts became not only signs for [passive visual] sensations but independent [active intentional processes along the lines of Brentano].... And now many acts were recognized which previously had not existed for psychology: Attending and recognizing, willing and rejecting, comparing and differentiation, and many more.... [P]revious psychology [defined] these acts through their symptoms. Attention was considered as a group of tension and muscle sensations, because so-called strained attention gives rise to such sensations [see Titchener (1908; 1910) and Wundt (1912) in this regard]. Similarly, willing [volition] was dissolved into images of motions because they usually precede an external act of the will.... With the recognition of these [as] acts... The center of gravity of mental life had to be moved. Previously one could say: We are attentive because our eyes are fixed on a particular point in the visual field and the muscles that keep the eyes in that position are tensed. It now became clear that this conception inverted the real state of affairs and that what it should rather say is: We direct our eyes toward a certain point and strain our muscles because we want to observe it. Activity became the central focus, receptivity and the mechanism of images secondary" (Külpe, 1912).

From Külpe's above comment about the "center of gravity" shifting toward "activity," one can understand that his approach was not just a rejection of the radical elementism of Titchener (who portrayed higher mental processes as merely additive combinations of elements), but also an attempted remedy for the passivity of Wundt's 'creative synthesis' approach by rejecting the analogy to "chemistry" altogether. The active organism (in particular the adult human mind with its determining tendencies) is being appealed to as a molar unit of analysis for psychological experiments on thought-processes. Elementism is avoided by showing that meaning (as in the case of verbal reasoning) has an existence and properties of its own, and Wundt's passive account of the emergence of these new properties is remedied by introducing the concept of determining tendencies (that the organism is doing something with information it receives in an active, intentional way).

The implication for experimental method of Külpe's departure from Wundt's position is a new emphasis upon the "tasks" being carried out in experimental situations. For they are just as important (he maintains) as the structure, control and measurement of external stimuli that was emphasized in Wundt's approach to experimentation:

"No psychological experiments are imaginable without tasks! The tasks must, therefore, be considered just as important an experimental condition as the apparatus and the stimuli that it presents. A variation in the task [e.g., instructions as to what is to be attended to], is at least as important an experimental procedure as a change in external experimental conditions [those emphasized by Wundt]....

This importance of the task and its effect on the structure and course of mental events could not be explained with the [theoretical] tools of association psychology. Rather, Ach [1905] was able to show that even associations of considerable strength could be overcome with a counteracting task. The force with which a determining tendency [from the organism] acts is not only greater than the familiar reproductive tendencies [from varied conditions of stimulation], it also derives from a different source and its effectiveness is not tied to [merely passive] associative relations" (Külpe, 1912).

The systematic strivings of the Würzburg school can be summed up as an attempt to expand 'that which would need to be referenced to' by psychologists in the method of scientific introspection. In the area of attention, for instance, Wundt's (1912) analytical distinction between "apprehension" versus its creative resultant "apperception" was a position very similar to Titchener's (1910) openly additive treatment of "focus and margin." In both of these conservative theoretical treatments, attention is portrayed as a passive occurrence, as an unexplained shift in the mental state of the organism. Külpe is attempting to expand experimental analysis beyond the merely descriptive (additive and mental chemistry) models of attentional states (that which happens to the observer) toward working out an active account of the intentional process of attention (how and why attentional shifts take place). Such an account requires reference to preparatory mental sets and determining tendencies.

Concluding Remarks for Section 3:

Hopefully you will be starting to get a feel for what the empirical and theoretical implications are of taking a specific set of constrained philosophical assumptions and attempting to build a psychological system upon that basis. The main problematic assumptions adopted by the figures covered in this Section have been representionalism, vitalism, methodological parallelism, and the "Critical positivism" of Mach and Avenarius.

Representationalism (a.k.a., indirect realism or the indirect theory of perception) featured prominently in the views of British associationist thinkers (David Hartley, James Mill, John Stuart Mill) with Thomas Brown being an exception because (as part of the Scottish School) he followed the so-called naive direct realist approach of his mentor Thomas Reid (see Section 2). Various forms of the indirect (enrichment) theory of perception were also carried forward into the German physiological and psychophysical traditions of research (as exemplified in the views of Johannes Müller, Fechner, and then Helmholtz); as well as into the very definition of psychology postulated by Wundt (1896), Titchener (1896) and Külpe (1893).

Instead of suggesting that physics deals with events in the world and psychology deals with consciousness or mental life (or any number of seemingly obvious direct realist ways in which to divide up the subject matter of the sciences), all three of these early "discipline-building figures" (Wundt, Titchener, Külpe) started out by defining the territory of psychology in terms of "sensory experience" -i.e., into "mediate versus immediate experience" or the rather more equivocal independent versus dependent "point of view."

At some point in his career, however, Oswald Külpe, -probably at the time of writing his Einleitung in die Philosophie (Introduction to Philosophy) 1895- started to come under the influence of Franz Brentano (1838-1917). Brentano (a philosopher at Würzburg from 1866-1873 and then at Vienna 1874-1880) was also working within the confines of the representationalist assumption, but his solution to the logical limitations which it imposed was a much more interesting one. That which is "psychological," he suggests, is "intentional" and that which belongs to physics is not:

"Every mental phenomenon is characterized by what the Scholastics of the Middle Ages called the intentional... what we might call... reference to a content, direction toward an object... Every mental phenomenon includes something as object within itself, although they do not all do so in the same way. In presentation something is presented, in judgment something is affirmed or denied, in love, loved, in hate, hated, in desire, desired, and so on" (Brentano, Psychology from an empirical standpoint [Psychologie vom epirischen Standpunkte], 1874).

Brentano stressed that psychic processes (ideas, judgments, emotions) are acts which are intentional (directed toward something). In other words, when we look at a book the book doesn't look back at us. The book does not take us as an object, we take it as an object. Brentano's philosophy was an attempt to divide up the world in terms of the subject-object relationship and it constitutes a first step (in Germany) to break free from the traditional constraints of representationalism. Out of his position grew various forms of phenomenological analysis of thought-processes including that of Edmund Husserl and Oswald Külpe's Würzburg school of psychological researchers.

But reference to such intentional acts and final causes (the teleological ends of the mental acts being carried out) were inimical to Titchener's elemental positivism because they were considered "metaphysical." Similarly, the active phenomenological aspects of the tasks being referred to in the Würzburg studies were inimical to the passive creative synthesis account of Wundt. It was on such methodological grounds, therefore, that both Titchener and Wundt critiqued the Würzburg experiments. The three-way split between Wundt, Titchener, and Külpe was not one of point of fact but one of the method of collection and theoretical interpretation of those facts.

The resulting disciplinary controversy (regarding the respective import of phenomenological, experimental, and cultural methods, as well as the very definition of psychology), however, was never satisfactorily resolved in Germany, partly because Külpe died of influenza in 1915 at age 53. Wundt outlived his most rebellious student to retire in 1917 (at the age of 85) and even published his memoirs in 1920 before passing away two weeks after his 88th birthday. Meanwhile, Titchener, who from 1909 onward adopted the self-serving authoritative attitude that there is "less prospect of gain from a revolution than from persistent work under the existing regime", stubbornly adhered to his orthodox "structural" psychology (which recoiled from the wider American context of functional-developmental, comparative-animal, and applied psychology) until his death in 1927.

Resolution of the philosophical and disciplinary issues raised by the initial round of disciplinary strivings in Germany would come only after evolutionary theory was adopted, applied, and refined in both Britain and America. It is to these early years of the adoption and application of evolutionary theory in psychology that we turn to in Section 4.

With regard to how Section 4 relates back to the content covered in Section 3, let's emphasized that William James will be the first major late 19th century figure that does not define psychology by its relationship to physics. There are two very good reasons for that: (1) James was not a positivist (but rather an explicit anti-positivist who openly embraces 'pragmatic' metaphysical positions like direct realism); and (2) his approach to psychology was informed by evolutionary theory (which for him requires an appeal to the developmental aspects of psychological processes).

In other words, having considered in Section 3 the numerous methodological similarities between Wundt, Titchener, and the early Külpe (whose pre-evolutionary positions dominated the initial German tradition of psychological discourse), what we should be prepared for now is something very different in William James. You will detect throughout that I have tremendous sympathy for figures like James and I will not attempt to hide that fact because part of my job is to make recommendations to you. The object lesson in this respect will be: If you are looking for a disciplinary model to emulate, don't pick Titchener, pick James. You'll see why.

Posted while in progress: Sept-Nov, 2003; Minor Grammatical changes: January & April, 2008.

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