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3. Mind, Brain, and the Experimental Psychology of Consciousness

It is in the work of Gustav Theodor Fechner (1801-1887) that we find the formal beginning of experimental psychology. Before Fechner, as Boring (1950) tells us, there was only psychological physiology and philosophical psychology. It was Fechner "who performed with scientific rigor those first experiments which laid the foundations for the new psychology and still lie at the basis of its methodology" (p. 275).

[Figure 37] Fechner [see figure 37] was born in Gross-Sächen, Prussia. At the age of 16 he enrolled in medicine at the University of Leipzig where he studied anatomy under Weber. No sooner had he received his medical degree, however, than his interest began to shift toward physics and mathematics. By 1824, he was lecturing in physics and in 1834, with over 40 publications to his credit, including an important paper on the measurement of direct current, he was appointed Professor of Physics at Leipzig.

Fechner's psychological interests began to manifest themselves toward the end of the 1830s in papers on the perception of complementary and subjective colors. In 1840, the year in which an article on subjective afterimages appeared, Fechner suffered a nervous collapse. Exacerbated by a painful injury to the eyes sustained while gazing at the sun during his research, Fechner's ailment manifested itself in temporary blindness and prostration. He resigned his position at Leipzig and went into a lengthy period of virtual seclusion during which his interests turned increasingly toward metaphysics. In 1848, the year of his return to the University as Professor of Philosophy, he completed Nanna, oder Über das Seelenleben der Pflanzen, a metaphysical treatise that contains his first explicit, philosophical treatment of the problem of the relationship of mind to body.

In Nanna, and in the more important Zend-Avesta (1851), Fechner sketched out a dual-aspect, monistic, pan-psychical mind/body view. In a famous metaphor, later adopted by Lewes, Fechner likened the universe, which is at one and the same time both active consciousness and inert matter, to a curve that can be regarded from one point of view as convex and from another as concave yet still retains its essential integrity. In line with this approach to mind/body, Fechner laid out a future program for psychophysics -- to demonstrate the unity of mind and body empirically by relating increase in bodily energy to corresponding increase in mental intensity.

[Figure 38] Between 1851 and 1860, Fechner worked out the rationale for measuring sensation indirectly in terms of the unit of just noticeable difference between two sensations, developed his three basic psychophysical methods (just noticeable differences, right and wrong cases, and average error) and carried out the classical experiments on tactual and visual distance, visual brightness, and lifted weights that formed a large part of the first of the two volumes of the Elemente der Psychophysik [39, see figure 38]. Fechner's aim in the Elemente was to establish an exact science of the functional relationship between physical and mental phenomena. Distinguishing between inner (the relation between sensation and nerve excitation) and outer (the relation between sensation and physical stimulation) psychophysics, Fechner formulated his famous principle that the intensity of a sensation increases as the log of the stimulus (S = k log R) to characterize outer psychophysical relations. In doing so, he believed that he had arrived at a way of demonstrating a fundamental philosophical truth: mind and matter are simply different ways of conceiving of one and the same reality.

While the philosophical message of the Elemente was largely ignored, its methodological and empirical contributions were not. Fechner may have set out to counter materialist metaphysics; but he was a well-trained, systematic experimentalist and a competent mathematician and the impact of his work on scientists such as Helmholtz, Ernst Mach, A.W. Volkmann, Delboeuf, and others was scientific rather than metaphysical. By combining methodological innovation in measurement with careful experimentation, Fechner moved beyond Herbart to answer Kant's second objection regarding the possibility of scientific psychology. Mental events could, Fechner showed, not only be measured, but measured in terms of their relationship to physical events. In achieving this milestone, Fechner demonstrated the potential for quantitative, experimental exploration of the phenomenology of sensory experience and established psychophysics as one of the core methods of the newly emerging scientific psychology.

[Figure 39] As Fechner was putting the finishing touches on the Elemente, a young physiologist, Wilhelm Wundt (1832-1920), was settling into a position as assistant to Helmholtz, who had come to Heidelberg from Bonn to direct the Physiological Institute. Wundt [see figure 39] was born at Neckarau, in the vicinity of Mannheim and received his early education at the hands of a private tutor and at the Bruchsal Gymnasium. At age 19, he set off to study medicine at Tübingen, where his uncle, Friedrich Arnold, held the Chair in Anatomy and Physiology. During his first summer semester, he worked intensively on the study of cerebral anatomy under Arnold's guidance and by the end of the summer he had decided to make physiology his career. When his uncle moved to Heidelberg to direct the Institute of Anatomy, Wundt followed, completing his medical studies in 1855. After a year of hospital work and a journey to Berlin for a semester of study under Müller and Du Bois-Reymond, Wundt returned to Heidelberg in 1857 as Dozent in Physiology, becoming assistant to Helmholtz in the following year.

During this period, Wundt seems to have availed himself but little of his contact with Helmholtz. Carrying out much of his experimental work in his own home and on his own time, Wundt began the study of sense perception that led to a series of publications collected, in 1862, as his Beiträge zur Theorie der Sinneswahrnehmung [40]. The Beiträge consisted of six previously published articles on sense perception preceded by a methodological introduction. In these articles, Wundt provided the basics of a psychological theory of the perception of space (including some discussion of the need for unconscious inference, apparently arrived at in independence of Helmholtz), reviewed the history of theories of vision, analyzed the psychological function of sensations arising from visual accommodation and eye movement, presented the results of experiments on binocular contrast effects and stereoscopic fusion, and argued, contra Herbart, that the content of consciousness at a given instant always consists of a single, unconsciously integrated, percept.

Although the body of the Beiträge is important in its own right for exemplifying the direction that Wundt' work was taking, it is his introduction on method, written specifically for the Beiträge, which marked the emergence of Wundt's plan for an experimental psychology. Rejecting a metaphysical foundation for psychology, Wundt argued for the need to transcend the limitations of the direct study of consciousness through the use of genetic, comparative, statistical, historical, and, particularly, experimental methods. Only in this way, he suggested, would it be possible to come to a needed understanding of conscious phenomena as "complex products of the unconscious mind" (p. xvi). As the young Wundt was engaged in thinking through the prerequisites of an experimental psychology, Helmholtz, his immediate superior, the Director of his Institute, was in many ways already engaged in carrying out such a program.

[Figure 40] Hermann Ludwig Ferdinand von Helmholtz (1821-1894) was born in Potsdam and educated at the Potsdam Gymnasium and at the Friedrich Wilhelm Medical Institute in Berlin. In Berlin, he came under the influence of Müller and in 1842, at 21 years of age, he graduated with a degree in medicine and entered the service as a Prussian Army physician. In reaction to Müller's vitalism, which he rejected, Helmholtz [see figure 40] became interested in clarifying the physiological basis of animal heat, a phenomenon that was sometimes used to help justify vitalism. This led in 1847 to a famous paper on the conservation of energy, which in turn brought Helmholtz the offer of a Professorship of Physiology at Königsberg, where he remained from 1848 to 1855. In 1855, he moved to Bonn and from Bonn, in 1858, to Heidelberg to serve as Director of the Institute of Physiology.

It was during the Bonn and Heidelberg periods that Helmholtz made his most fundamental contributions to the newly emerging experimental psychology. From 1856 to 1866, the Handbuch der physiologischen Optik [41] appeared in parts that were gathered into a single volume in 1867. In 1863, while the Optik was still appearing, Helmholtz published Die Lehre von den Tonempfindungen. While we will focus on the Optik here, these two works taken together defined the problematic for the experimental psychology of visual and auditory perception for decades to follow.

In the Optik, Helmholtz extended Müller's doctrine of the specific energies of nerves to offer a comprehensive theory of color vision and a famous unconscious inference theory of perception. In the theory of color vision, Helmholtz reasoned that just as the differences between sensations of sound and light reflect the specific qualities of auditory and visual nerves, sensations of color may depend on different kinds of nerves within the visual system. Since the laws of color mixture suggest that virtually all hues can be obtained by various combinations of three primary colors, it seemed to Helmholtz that the perceived hue, brightness, and saturation of color must be derived from varying activity in three primary kinds of nerve fibers in the eye.

In his theory of perception, Helmholtz started from the recognition that Müller's doctrine of specific nerve energies implied the fact that sensations do not provide direct access to objects and events but only serve the mind as signs of reality. Perception, on this view, requires an active, unconscious, automatic, logical process on the part of the perceiver which utilizes the information provided by sensation to infer the properties of external objects and events. In this regard, Helmholtz anticipated much of later top-down cognitive psychology.

In an earlier period, Helmholtz had also made another major contribution to physiology. Stimulating nerves at various distances from a muscle and measuring the time it took for muscular contraction, he estimated the rate of travel of the nervous impulse, and in the process incidentally introduced the technique of reaction-time into physiology. Between 1865 and 1868, another great physiologist, Franciscus Cornelis Donders (1818-1889) assimilated the reaction-time procedure to psychology, employing it to study the time taken up by mental operations.

[Figure 41] Donders [see figure 41] was born in the town of Tilburg, in the Netherlands, and entered the University of Utrecht as a medical student at the age of 17. Upon receipt of the degree, he joined the military as a surgeon and, at the age of 24, was invited to teach at the Military Medical School at Utrecht. Five years later Donders was offered a position as extraordinarius at the University of Utrecht, which he accepted, remaining there for the remainder of his career.

In 1865, Donders published a preliminary communication in which he reported work carried out with a student, Johan Jacob de Jaager, and summarized more fully in de Jaager's doctoral dissertation, De physiologische tijd bij psychische processen (1865). Reasoning that reaction time was additive, Donders separately assessed the time taken to respond to a stimulus under conditions of choice and simple non-choice. Subtracting simple from choice reaction-time, Donders computed the interval taken by the decision process. In 1868, in a classic paper appearing in German, "Die schnelligkeit psychischer Processe" [42], Donders provided the definitive report of the results of this work and its extension to discrimination times. Although the specifics of Donder's findings are of little interest today, his use of the reaction technique to measure the time taken by mental processes exerted a major impact on his contemporaries and reaction-time was installed, along with psychophysics, as a method of choice in the early experimental laboratory.

As Donders investigated reaction-time, Wundt, still at Heidelberg, began to work toward the conception of physiological psychology that was to serve as the basis for his systematic approach to experimentation. In 1867, in a new quarterly journal of psychiatry founded by Max Leidesdorf and Theodor Meynert, Wundt published an invited article, "Neuere Leistungen auf dem Gebiete der physiologischen Psychologie." Under the banner of physiological psychology, he reviewed recent literature on visual space perception and the measurement of the time taken by mental operations. As an outgrowth of this review, Wundt offered a series of lectures on physiological psychology in the Winter of 1867/1868. These lectures he repeated only once again, in 1872/1873, as he was preparing the text that Boring (1950), steeped as he was in the Wundt-Titchener tradition, called "the most important book in the history of modern psychology" (p. 322).

Issued in two parts, in 1873 and 1874, the Grundzüge der physiologischen Psychologie [43] was the first comprehensive handbook of modern experimental psychology. It was, as Boring tells us, "on the one hand, the concrete result of Wundt's intellectual development at Heidelberg and the symbol of his metamorphosis from physiologist to psychologist, and, on the other hand ... the beginning of the new 'independent' science" (Boring, p. 323). Although the theories elaborated in the Grundzüge changed over the five major revisions during which it grew from one to three volumes, the essential structure of Wundt's system, "his great argument for an experimental psychology" (Boring, p. 323), had been reasonably well worked out by 1874.

In that year, Wundt accepted a call to the University of Zurich, where he remained only a year, moving in 1875 to Leipzig to assume the chair in philosophy. Although Boring (1950) claimed that upon his arrival in Leipzig Wundt was allocated space for experimental demonstrations adjunctive to his lectures, there is no evidence to that effect (Bringmann et al., 1980). Indeed, it would appear that from 1875 to 1879, Wundt devoted himself largely to the duties entailed in his new teaching position.

[Figure 42] On the 24th of March, 1879, however, Wundt submitted a petition to the Royal Saxon Ministry of Education in which he formally requested a regular financial allocation for the establishment and support of a collection of psychophysical apparatus. Although his request was denied, Wundt seems as early as the Winter of 1879/1880 to have nonetheless allowed two students, G. Stanley Hall and Max Friedrich, "to occupy themselves with research investigations" (Wundt, 1909, p. 1). This research took place in a small classroom in the Konvict Building that had earlier been assigned to Wundt for use as a storage area. Humble though it may have been, this small space constituted the first laboratory in the world devoted to original psychological research [see figure 42].

Experimental psychology, born with Fechner, nurtured by Helmholtz and Donders, was to be raised by Wundt. Over the years until his retirement in 1917, Wundt served as the de facto parent of the "new" psychology. Students from all over the world, especially from the United States, journeyed to Leipzig to learn experimental technique and to return to their home institutions imbued with the spirit of scientific psychology.

Psychology In America

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Wozniak, Robert H. "Mind and Body: Rene Déscartes to William James";
Bryn Mawr College, Serendip 1995
Originally published in 1992 at Bethesda, MD & Washington, DC by the National Library of Medicine and the American Psychological Association.

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