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For example, suppose that for a 20-gram standard mass, participants do not notice that an object is heavier until it weighs at least 22 grams and do not notice that it is lighter until it weighs less than 18 grams (these numbers are for illustration only). Then DI = 2, and DI/I = 2/20 = 0.1. According to Weber’s law, the jnd for a 60-gram standard object should be 60 grams * 0.1 = 6 grams, so participants should not notice a difference in weight between the standard object and a test object until the test object weighs 54 grams or less, or 66 grams or more. Similarly, there should be no noticeable differences between masses between 90 and 110 grams for a 100-gram standard object (100 grams * 0.1 = 10 grams), or between masses of 900 and 1,100 grams if the standard object weighs one kilogram (1,000 grams * 0.1 = 100 grams), and so on.
These findings provide Wundt with a reply to Kant’s first objection, that mathematical methods cannot be applied to perception. Wundt points out that time is not the only variable in experience: there is also the quality of the sensation, which is proportional to the stimulus. “But, as a matter of fact, our sensations and feelings are intensive magnitudes, which form temporal series. The course of mental events has, therefore, at any rate two dimensions; and with this fact is given the general possibility of its presentation in mathematical form” (1874, p. 6).
This takes care of Kant’s first objection to scientific psychology. Wundt also relies on psychophysics to rebut Kant’s claim that one cannot get knowledge of the mind from introspection. First, Wundt agrees with Kant that ordinary introspection is unreliable. Psychophysics, though, shows that one can nonetheless measure experience. It is worth quoting Wundt at length on this:
The arguments that Kant adduces in support of his second objection, that the inner experience is inaccessible to experimental investigation, are all derived from purely internal sources, from the subjective flow of processes; and there, of course, we cannot challenge its validity. Our psychical experiences are, primarily, indeterminate magnitudes; they are incapable of exact treatment until they have been referred to determinate units of measurement, which in turn may be brought into constant causal relations with other given magnitudes. But we have, in the experimental modification of consciousness by external stimuli, a means to this very end – to the discovery of the units of measurement and the relations required. Modification from without enables us to subject our mental processes to arbitrarily determined conditions, over which we have complete control and which we may keep constant or vary as we will. Hence the objection urged against experimental psychology, that it seeks to do away with introspection, which is the sine qua non of any psychology, is based upon a misunderstanding. The only form of introspection which experimental psychology seeks to banish from the science is that professing self-observation which thinks it can arrive directly, without further assistance, at an exact characterization of mental facts, and which is therefore inevitably exposed to the grossest self-deception. The aim of the experimental procedure is to substitute for this subjective method, whose sole resource is an inaccurate inner perception, a true and reliable introspection, and to this end it brings consciousness under accurately adjustable objective conditions. (1874, p. 7)
Here, Wundt not only gives a (partial) response to Kant, but also lays out the plan for the whole of his psychology. First, Wundt makes a distinction between inner and outer experience, acknowledging that inner experience is indeed inaccessible to experimental methods. Indeed, what is generally known as Wundtian psychology, the kind that was undertaken in his laboratory at Leipzig and in which he trained nearly every member of the first generation of scientific psychologists, is his science of outer experience. Wundt’s psychology of inner experience, called Völkerpsychologie, had virtually no influence on later psychology (Leahey 2000). Völkerpsychologie (Wundt 1912) applies historical and anthropological methods of the kind Kant recommended in his Anthropology from a Pragmatic Point of View (1798). So Wundt accepts Kant’s arguments about inner experience, but argues that it is possible to experimentally access outer experience using the method of psychophysics. Psychophysics does not do away with introspection, but uses trained introspectors in highly controlled circumstances to experiment upon the basic elements of conscious experience. Subjects, for example, are presented with a series of tones that are increasingly high in pitch and are asked to report when they experience a pitch difference; or they are asked to press a key when a light appears on a screen; or they are asked to press when a blue light (but not a red light) appears on a screen. Experiments such as these are used to examine the variety of sensations humans are capable of having, and the temporal duration of sensory processes.
Using psychophysics to study outer experience places strict limits on the scope of experimental psychology. According to Wundt, psychology is the study of the elements of immediate conscious experience:
Psychological analysis leaves us with two such elements [of conscious experience], of specifically different character: with sensations, which as the ultimate and irreducible elements of ideas we may term the objective elements of the mental life, and with feelings, which accompany these objective elements as their subjective complements, and are referred not to external things but to the state of consciousness itself. In this sense, therefore, we call blue, yellow, warm, cold, etc., sensations; pleasantness, unpleasantness, excitement, depression, etc., feelings. (1874, p. 12)
Sensations and feelings are the atoms of conscious experience. They are combined by unconscious processes to form the molecules: sensations combine to form ideas; feelings combine to form complex feelings. Wundt’s experimental psychology was reductionist in that it focused on the smallest possible bits of conscious experience. It was also atomistic in that it thought that the elements maintained their identities in whatever context they appeared. (“As conscious contents, blue is and remains blue, and the idea of an object is always a thing ideated in the outside world, whether the external stimulus or the thing outside of us be really present or not” [1874, pp. 13–14].)
Wundt’s pioneering scientific psychology was, thus, a reductionist, atomistic science of outer experience. It was a successful science, and Wundt was very influential. He published more than 60,000 pages during his lifetime, and educated thousands of students in his methods (Fancher 1995). One of these students was William James, the “founding father” of American psychology. James later became an opponent of Wundt’s methods, which he mocked as “brass instrument psychology.” Another was E. B. Titchener, a proponent of Wundt’s methods who founded the psychology department at Cornell. In his 1898 textbook Titchener claimed to have identified more than 30,000 elementary visual sensations (1898b, p. 40). Most importantly for current purposes, Wundt’s was the scientific psychology that was in place when Husserl began his work as a phenomenologist. Husserl criticized Wundt specifically in establishing his phenomenological methods. Moreover, the psychological theories of the first half of the twentieth century that we will discuss later in the book defined themselves explicitly in opposition to Wundt’s views. The Gestalt psychologists, who were profoundly influential on Merleau-Ponty and on Gibson, rejected Wundt’s atomism (see Chapter 5). The functionalists and pragmatists, who were profoundly influential on Gibson, also rejected Wundt’s narrow focus on conscious experience (see Chapter 10).
2.2 William James and functionalism
At the same time that Wundt developed his scientific psychology, William James was teaching a very different version of the science, one whose primary influence was Darwin. For Wundt, scientific psychology was the use of the methods of psychophysics to study simple sensations. As he wrote in his 1890 textbook The Principles of Psychology, James doubted that there even were simple sensations, and thought that Wundt’s focus on them was harmful to the science.
Most books start with sensations, as the simplest mental facts, and proceed synthetically, constructing each higher stage from those below it. But this is abandoning the empirical method of investigation. No one ever had a simple
