Fechner, Gustav Theodor

(b. Gross-Särchen, near Halle, Germany, 19 April 1801; d. Leipzig, Germany, 18 November 1887)

psychology.

Fechner was the second of five children of Samuel Traugott Fechner, a rural, innovative Lutheran preacher, and Johanna Dorothea Fischer Fechner. The precocious child had learned Latin from his father by the time of the latter’s death, when Fechner was five. After attending the Gymnasium at Soran (near Dresden, where the family moved in 1815), in 1817 Fechner matriculated at the University of Leipzig, where he spent the rest of his life. He took the M.D. there in 1822 but never practiced medicine. In 1833 he married Clara Volkmann, the sister of his colleague and friend A. W. Volkmann, a physiologist in vision.

Fechner’s first writings were satirical pieces that he published under the pseudonym “Dr. Mises.” The first of these was written in 1821; they appeared sporadically over the next twenty-five years. Fantastical and by turns strained or brilliant, these pieces usually attack the materialism popular in Germany early in the nineteenth century—or Nachtansicht, as Fechner called it—in contrast with his own Tagesansicht, in which life and consciousness are coequal with matter.

Fechner’s first scientific work was in physics, lecturing on it in 1824 (as ordinarius, wihtout pay), translating physics and chemistry texts from the French (by which he earned his living), and conducting investigations in electricity, particularly on Ohm’s law. In 1831 he published Massbestimmungen über die galvanische Kette, a paper of great importance on quantitative measurements of the galvanic battery. This made his reputation as a physicist, and he was appointed professor of physics in 1834. During this period, the only indications of his future interest in psychological problems were his satires, two papers on complementary colors and subjective colors (1838), and his famous paper on subjective afterimages, published in 1840.

Fechner then plunged into a long, serious neurotic illness which necessitated his resignation from his chair of physics in 1839. This began somatically with a partial blindness brought on by gazing at the sun through colored glasses in the experiments on colors and afterimages; it then deepened psychologically into an inability to take food, various psychotic symptoms, and a year of severe autistic thinking. Then on 5 October 1843, having lived for three years in the dark and despairing of ever seeing again, Fechner ventured into his garden, unwound the bandages he wore around his eyes, and found his vision not only regained but abnormally powerful, since he had semihallucinatory experiences of seeing the souls of flowers. His recovery was then slow and progressive.

This peak experience in the garden is reflected in his next work, Nanna oder über das Seelenleben der Pflanzen (“Nanna, or the Soul Life of Plants,” 1848). In this philosophically diffuse book as well as in his 1851 book, Zend-Avesta oder über die Dinge des Himmels und des Jenseits (“Zend-Avesta, or Concerning Matters of Heaven and the World to Come”), Fechner developed what has been called his panpsychism, a development of his Tagesansicht; since mind and matter were two aspects of the same thing, the entire universe could be looked at from the point of view of its mind.

But how could this be made scientific? On the morning of 22 October 1850 (called commemoratively by psychophysicists Fechner Day), while Fechner was awaking in bed, the solution came. It was to make the relative increase of stimulation the measure of the increase of the corresponding sensation; and this suggested that the arithmetical series of perceived intensities might correspond to a geometrical series of external energies.

In part, this solution to Fechner’s problem was based upon Helmholtz’s famous “On the Conservation of Force,” published three years earlier. Since energy could neither be created nor be destroyed, all energy impinging on sense organs traversed the nervous system and ended in effectors. Sensation was the mental aspect of this, which had to be just as orderly and related to these physical events in an orderly manner. The relation between sensation and these neurological events he called “inner psychophysics.” This was impossible to study. It was, therefore, the relationship of sensation to the external stimulus energy, or outer psychophysics, that could alone be studied.

These ideas, after a decade of thought and experiment, resulted in 1860 in Fechner’s classic work, the Elemente der Psychophysik, a text of the “exact science of the functional relations or relations of dependency between body and mind.” Through its sometimes redundant details are developed three of the basic methods of a new science to be called psychophysics:

1. The method of just noticeable differences, later called the method of limits. The difference between two discriminable stimuli is gradually decreased until discrimination is just lost; and conversely, the difference between two stimuli that are not discriminable is gradually increased until discrimination is barely possible: the average of these two determinations is a measure of the just noticeable difference.

2. The method of right and wrong cases, later called the method of constant stimuli, or simply the constant method, which has become, since the work of G. E. Müller and F. M. Urban, the most important. A range of stimuli are used, none of which is adjustable; a standard stimulus is compared in some given respect with each of a series of similar stimuli, presented in chance order: from the percentage of correct judgments with each comparison stimulus, a threshold is mathematically determined.

3. The method of average error. Whereas the two foregoing methods are partly systematizations of work by others, this method was original with Fechner in collaboration with his brother-in-law, Volkmann. A variable stimulus is adjusted sundry times to apparent equality with a standard, the average adjustment being the “constant error” and its standard deviation the sensitivity. These methods were used by Fechner in classical experiments in lifted weights, visual brightnesses, tactual and visual distances, temperature sensitivity, and even a classification of stars by magnitude following Steinheil.

But this methodology is mere apparatus to carry the central and pervading conception of the Elemente, Fechner’s fascinating development of the Weber fraction into what has come to be known as the Weber-Fechner law. E. H. Weber, a senior colleague of Fechner at Leipzig, concluded after a series of elegant studies on lifted weights, judged line lengths, and various tactual sensations, that the just noticeable difference in stimulus intensity is a constant fraction of the total intensity at which it is measured. These experiments were first described in Latin in 1834 but achieved attention only when brought together with other facts in Weber’s famous chapter on touch in Rudolph Wagner’s Handwörterbuch der Physiologie (Brunswick, 1846). This may be expressed as

where R is Reiz, or stimulus, and ?R is the amount of increase in R necessary for a subject to see any difference. This is approximately true for the middle range of sensory stimulation in any modality in men, or in animals where a behavioral response takes the place of an introspected difference in sensation.

Fechner assumed that on the mental side there is a corresponding increase in sensation, ?S, and that all such ?S’s are equal and can be treated as units, whence

where C is the constant of proportionality. Integrating, and solving for the constant of integration at threshold where S = 0,

S = C log R,

where R is measured in units of its threshold value. This is the fundamental relation between mind on the left-hand side of the equation, and matter on the right. It is now known as the Weber-Fechner law, although Fechner with confusing generosity called it Weber’s law.

While the methodology of the Elemente is sound and permanent, its theoretical purpose and its working out into Fechner’s law kindled immediate controversy, which is still far from being resolved. Even before 1860, Fechner’s ideas resulted in papers by Helmholtz and Mach on the new psychophysics. And Wilhelm Wundt, in his first psychological publications from 1862 on, made Fechner’s work centrally important. His detractors, on the other hand, claimed that Fechner had not measured sensation at all. Their fundamental objections were (1) that it is meaningless to say that one ?S equals another unless S is independently measurable, and (2) what has been called the quantity objection: in experience, pink is not part of scarlet, nor a thunderclap a summation of murmurs.

As Fechner founded psychophysics with this decade of work, so in the next decade (1865–1876) he founded experimental aesthetics, publishing his Vorschule der Ästhetik in 1876. This work treats of its methods, principles, and problems, particularly that of the “golden section,” or most aesthetically pleasing relation of length to breadth of an object, a kind of Weber’s fraction for aesthetics. He endlessly measured the dimensions of pictures, cards, books, snuffboxes, writing paper, and windows, among other things, in an attempt to develop experimental aesthetics “from below,” in rebellion against the Romantic attempt “from above down” first to formulate abstract principles of beauty.

In the final decade of his life, the turbulent wake of his Elemente drew Fechner back into psychophysics. In 1882 he answered his critics with his last important book, Revision der Hauptpunkte der Psychophysik. This helped to place Fechner’s psychophysics even more securely as a cornerstone of the new so-called experimental psychology as it was to be developed in the latter part of the century by Wundt and others.

BIBLIOGRAPHY

I. Original Works. Fechner’s chief works are Massbe stimmungen über die galvanische Kette (Leipzig, 1831), which is available on microfilm in the “Landmarks of Science” series, I. Bernard Cohen, Charles C. Gillispie, et al., eds. (New York, 1967); Das Büchlein vom Leben nach dem Tode (Dresden, 1836; Leipzig, 1841, 1915, 1922; Hamburg, 1887, 1906), English trans. by H. Wernekke as On Life After Death (London, 1882; Chicago, 1906, 1914), another English trans. by M. C. Wadsworth, intro. by W. James, as The Little Book of Life After Death (Boston, 1904; New York, 1943); Nanna oder über das Seelenleben der Pflanzen (Leipzig, 1848, 1920; Hamburg, 1903); Zend Auesta oder über die Dinge des Himmels und des Jenseits, 3 vols. (Leipzig, 1851; Hamburg, 1906); Elemente der psychophysik, 2 vols. (Leipzig, 1860, 1889)—of which vol. I of the 1889 ed. includes a bibliography, originally compiled by R. Müller, of 175 of Fechner’s publications—English trans. of vol. I only by H. E. Adler, as Elements of Psychophysics, E. G. Boring and D. Howes, eds. (New York, 1966); Vorschule der Ästhetik (Leipzig, 1876); Die Tagesansicht gegenüber der Nachtansicht (Leipzig, 1879, 1904); and Revision der Hauptpunkte der Psychophysik (Leipzig, 1882).

II. Secondary Literature. On Fechner’s life, see the sympathetic biography by his nephew, J. E. Kuntze, Gustav Theodor Fechner (Dr. Mises), Ein deutsches Gelehrtenleben (Leipzig, 1892), which reprints the bibliography of Fechner’s works cited above. See also K. Lasswitz, Gustav Theodor Fechner (Stuttgart, 1896, 1910); and G. S. Hall, Founders of Modern Psychology, (New York, 1912), pp. 123–177.

On Fechner’s scientific contributions, see, in addition to the foregoing, T. Ribot, German Psychology of Today (New York, 1886), pp. 134–187; W. Wundt, Gustav Theodor Fechner (Leipzig, 1901); and M. Wentscher, Fechner und Lotze (Munich, 1925). Other bibliographical items on Fechner’s scientific work, as well as a good short introduction to him, are given in E. G. Boring, A History of Experimental Psychology (New York, 1929), pp. 265–287. William James’s scornful evaluation of Fechner and his work may be found in his Principles of Psychology, I (New York, 1890), 533–549. See also R. I. Watson, The Great Psychologists (Philadelphia, 1968), pp. 229–241.

Of recent revisions of the Weber-Fechner law, the most important are H. Helson and W. C. Michels, “A Reformulation of the Ferchner Law in Terms of Adaptation Level Applied to Rating Scale Data,” in American Journal of Psychology, 62 (1949), 355–368; S. S. Stevens, “On the Psychophysical Law,” in Psychological Review, 64 (1957), 153–181; R. D. Luce and W. Edwards, “The Derivation of Subjective Scales From Just Noticeable Differences,” ibid., 65 (1958), 222–237; and R. D. Luce and E. Galanter, “Discrimination,” in R. D. Luce, R. R. Bush, and E. Galanter, eds., Handbook of Mathematical Psychology, I (New York, 1963), 191–243, esp. 206–213.

See also H. Eisler, “A General Differential Equation in Psychophysics: Derivation and Empirical Test,” in Scandinavian Journal of Psychology, 4 (1963),1–8; M. Mashhour, “On Eisler’s General Psychophysical Differential Equation and His Fechnerian Integration,” ibid., 5 (1964), 225–233, a highly critical paper on Eisler; and J. C. Falmagne, “The Generalized Fechner Problem and Discrimination,” in Jounal of Mathematical Psychology, in press.

On the quantity objection specifically, see E. B. Titchener, Experimental Psychology, II, pt. 2 (London, 1905), xlvii–lxviii. E. G. Boring, “The Stimulus Error,” in American Journal of Psychology, 32 (1921), 449–471, particularly pp. 451–460, contains other references on the problem.

On Fechner’s more philosophical thought, see W. James, A Pluralistic Universe (New York, 1909), pp. 133–177; R. B. Perry, Philosophy of the Recent Past (New York, 1926), pp. 81–86; and G. S. Brett, History of Psychology, ed. and abridged by R. S. Peters (Cambridge, Mass., 1965), pp. 580–590.

Julian Jaynes