# Gustav Fechner

Gustav Fechner
Born
Gustav Theodor Fechner

19 April 1801
Died18 November 1887 (aged 86)
NationalityGerman
EducationMedizinische Akademie Carl Gustav Carus [de]
Leipzig University (PhD, 1835)
Known forWeber–Fechner law
Scientific career
FieldsExperimental psychology
InstitutionsLeipzig University
ThesisDe variis intensitatem vis Galvanicae metiendi methodis (1835)
Notable studentsHermann Lotze
InfluencesImmanuel Kant?
InfluencedGerardus Heymans
Wilhelm Wundt
William James
Charles Hartshorne
Ernst Weber
Sigmund Freud
Friedrich Paulsen
Ludwig von Bertalanffy

Gustav Theodor Fechner (/ˈfɛxnər/; German: [ˈfɛçnɐ]; 19 April 1801 – 18 November 1887)[1] was a German experimental psychologist, philosopher, and physicist. An early pioneer in experimental psychology and founder of psychophysics, he inspired many 20th-century scientists and philosophers. He is also credited with demonstrating the non-linear relationship between psychological sensation and the physical intensity of a stimulus via the formula: ${\displaystyle S=K\ln I}$, which became known as the Weber–Fechner law.[2][3]

## Early life and scientific career

Fechner was born at Groß Särchen, near Muskau, in Lower Lusatia, where his father was a pastor. Despite being raised by his religious father, Fechner became an atheist in later life.[4] He was educated first at Sorau (now Żary in Western Poland).

In 1817 he studied medicine at the Medizinische Akademie Carl Gustav Carus [de] in Dresden and from 1818 at the University of Leipzig, the city in which he spent the rest of his life.[5] He earned his PhD from Leipzig in 1835.

In 1834 he was appointed professor of physics at Leipzig. But in 1839, he injured his eyes in the research on afterimages by gazing at the sun through colored glasses,[6] while studying the phenomena of color and vision, and, after much suffering, resigned. Subsequently, recovering, he turned to the study of the mind and its relations with the body, giving public lectures on the subjects dealt with in his books. Whilst lying in bed, Fechner had an insight into the relationship between mental sensations and material sensations. This insight proved to be significant in the development of psychology as there was now a quantitative relationship between the mental and physical worlds.[7]

## Contributions

Fechner published chemical and physical papers, and translated chemical works by Jean-Baptiste Biot and Louis Jacques Thénard from French. He also wrote several poems and humorous pieces, such as the Vergleichende Anatomie der Engel (1825), written under the pseudonym of "Dr. Mises."

### Elemente der Psychophysik

Fechner's epoch-making work was his Elemente der Psychophysik (1860). He started from the monistic thought that bodily facts and conscious facts, though not reducible one to the other, are different sides of one reality. His originality lies in trying to discover an exact mathematical relation between them. The most famous outcome of his inquiries is the law known as the Weber–Fechner law which may be expressed as follows:

"In order that the intensity of a sensation may increase in arithmetical progression, the stimulus must increase in geometrical progression."

The law has been found to be immensely useful, but to fail for very faint and for very strong sensations. Within its useful range, Fechner's law is that sensation is a logarithmic function of physical intensity. S. S. Stevens pointed out that such a law does not account for the fact that perceived relationships among stimuli (e.g., papers coloured black, dark grey, grey, light grey, and white) are unchanged with changes in overall intensity (i.e., in the level of illumination of the papers). He proposed, in his famous 1961 paper entitled "To Honor Fechner and Repeal His Law", that intensity of stimulation is related to perception via a power-law.

Fechner's general formula for getting at the number of units in any sensation is Sc log R, where S stands for the sensation, R for the stimulus numerically estimated, and c for a constant that must be separately determined by experiment in each particular order of sensibility. Fechner's reasoning has been criticized on the grounds that although stimuli are composite, sensations are not. "Every sensation," says William James, "presents itself as an indivisible unit; and it is quite impossible to read any clear meaning into the notion that they are masses of units combined."

### The Fechner color effect

A sample of a Benham's disk

In 1838, he also studied the still-mysterious perceptual illusion of what is still called the Fechner color effect, whereby colors are seen in a moving pattern of black and white. The English journalist and amateur scientist Charles Benham, in 1894, enabled English-speakers to learn of the effect through the invention of the spinning top that bears his name, Benham's top. Whether Fechner and Benham ever actually met face to face for any reason is not known.

### The median

In 1878, Fechner published a paper in which he developed the notion of the median. He later delved into experimental aesthetics and thought to determine the shapes and dimensions of aesthetically pleasing objects. He mainly used the sizes of paintings as his data base. In his 1876 Vorschule der Aesthetik, he used the method of extreme ranks for subjective judgements.[8]

Fechner is generally credited with introducing the median into the formal analysis of data.[9]

### Synesthesia

In 1871, Fechner reported the first empirical survey of coloured letter photisms among 73 synesthetes.[10][11] His work was followed in the 1880s by that of Francis Galton.[12][13][14]

### Corpus callosum split

One of Fechner's speculations about consciousness dealt with brain. During his time, it was known that the brain is bilaterally symmetrical and that there is a deep division between the two halves that are linked by a connecting band of fibers called the corpus callosum. Fechner speculated that if the corpus callosum were split, two separate streams of consciousness would result - the mind would become two. Yet, Fechner believed that his theory would never be tested; he was incorrect. During the mid-twentieth century, Roger Sperry and Michael Gazzaniga worked on epileptic patients with sectioned corpus callosum and observed that Fechner's idea was correct.[15]

### Golden section hypothesis

Fechner constructed ten rectangles with different ratios of width to length and asked numerous observers to choose the "best" and "worst" rectangle shape. He was concerned with the visual appeal of rectangles with different proportions. Participants were explicitly instructed to disregard any associations that they have with the rectangles, e.g. with objects of similar ratios. The rectangles chosen as "best" by the largest number of participants and as "worst" by the fewest participants had a ratio of 0.62 (21:34).[16] This ratio is known as the "golden section" (or golden ratio) and referred to the ratio of a rectangle's width to length that is most appealing to the eye. Carl Stumpf was a participant in this study.

However, there has been some ongoing dispute on the experiment itself, as the fact that Fechner deliberately discarded results of the study ill-fitting to his needs became known, with many mathematicians, including Mario Livio, refuting the result of the experiment.[citation needed]

### The two-piece normal distribution

In his posthumously published Kollektivmasslehre (1897), Fechner introduced the Zweiseitige Gauss'sche Gesetz or two-piece normal distribution, to accommodate the asymmetries he had observed in empirical frequency distributions in many fields. The distribution has been independently rediscovered by several authors working in different fields.[17]

In 1861, Fechner reported that if he looked at a light with a darkened piece of glass over one eye then closed that eye, the light appeared to become brighter, even though less light was coming into his eyes.[18] This phenomenon has come to be called Fechner's paradox.[19] It has been the subject of numerous research papers, including in the 2000s.[20] It occurs because the perceived brightness of the light with both eyes open is similar to the average brightness of each light viewed with one eye.[18]

## Influence

Fechner, along with Wilhelm Wundt and Hermann von Helmholtz, is recognized as one of the founders of modern experimental psychology. His clearest contribution was the demonstration that because the mind was susceptible to measurement and mathematical treatment, psychology had the potential to become a quantified science. Theorists such as Immanuel Kant had long stated that this was impossible, and that therefore, a science of psychology was also impossible.

Though he had a vast influence on psychophysics, the actual disciples of his general philosophy were few. Ernst Mach was inspired by his work on psychophysics.[21] William James also admired his work: in 1904, he wrote an admiring introduction to the English translation of Fechner's Büchlein vom Leben nach dem Tode (Little Book of Life After Death). Furthermore, he influenced Sigmund Freud, who refers to Fechner when introducing the concept of psychic locality in his The Interpretation of Dreams that he illustrates with the microscope-metaphor.[22][23][24]

Fechner's world concept was highly animistic. He felt the thrill of life everywhere, in plants, earth, stars, the total universe. Man stands midway between the souls of plants and the souls of stars, who are angels.[25] God, the soul of the universe, must be conceived as having an existence analogous to men. Natural laws are just the modes of the unfolding of God's perfection. In his last work Fechner, aged but full of hope, contrasts this joyous "daylight view" of the world with the dead, dreary "night view" of materialism. Fechner's work in aesthetics is also important. He conducted experiments to show that certain abstract forms and proportions are naturally pleasing to our senses, and gave some new illustrations of the working of aesthetic association. Charles Hartshorne saw him as a predecessor on his and Alfred North Whitehead's philosophy and regretted that Fechner's philosophical work had been neglected for so long.[26]

Fechner's position in reference to predecessors and contemporaries is not very sharply defined. He was remotely a disciple of Schelling, learnt much from Baruch Spinoza, G. W. Leibniz, Johann Friedrich Herbart, Arthur Schopenhauer, and Christian Hermann Weisse, and decidedly rejected G. W. F. Hegel and the monadism of Rudolf Hermann Lotze.

Fechner's work continues to have an influence on modern science, inspiring continued exploration of human perceptual abilities by researchers such as Jan Koenderink, Farley Norman, David Heeger, and others.

## Honours

### Fechner Crater

In 1970, the International Astronomical Union named a crater on the far side of the moon after Fechner.[27]

### Fechner Day

In 1985 the International Society for Psychophysics called its annual conference Fechner Day. The conference is now scheduled to include 22 October to allow psychophysicists to celebrate the anniversary of Fechner's waking up on that day in 1850 with a new approach into how to study the mind.[28] Fechner Day runs annually with the 2021 Fechner Day being the 37th.[29] It is organized annually, by a different academic host each year.[30][31] During the pandemic resulting from COVID-19, Fechner Day was held online in 2020 and 2021.

## Family and later life

Little is known of Fechner's later years, nor of the circumstances, cause, and manner of his death.

Fechner was the brother of painter Eduard Clemens Fechner and of Clementine Wieck Fechner, who was the stepmother of Clara Wieck when Clementine became her father Friedrich Wieck's second wife.[citation needed]

## References

1. ^ "Gustav Fechner - German psychologist and physicist". Encyclopedia Britannica. Retrieved 18 January 2019.
2. ^ Fancher, R. E. (1996). Pioneers of Psychology (3rd ed.). New York: W. W. Norton & Company. ISBN 0-393-96994-0.
3. ^ Sheynin, Oscar (2004), "Fechner as a statistician.", British Journal of Mathematical and Statistical Psychology (published May 2004), 57 (Pt 1), pp. 53–72, doi:10.1348/000711004849196, PMID 15171801
4. ^ Michael Heidelberger (2004). "1: Life and Work". Nature from within: Gustav Theodor Fechner and his Psychophysical Worldview. University of Pittsburgh Press. p. 21. ISBN 9780822970774. The study of medicine also contributed to a loss of religious faith and to becoming atheist.
5. ^
6. ^ Boring, E. G. (1950). A history of experimental psychology (2nd ed.). (pp. 284-295) Appleton-Century-Crofts.
7. ^ Schultz, P.D., & Schultz, S.E. (2008). A History of Modern Psychology.(pp. 81-82).Thompson Wadsworth.
8. ^ Michael Heidelberger. "Gustav Theodor Fechner". /statprob.com. Archived from the original on 4 March 2016. Retrieved 5 January 2014.
9. ^ Keynes, John Maynard; A Treatise on Probability (1921), Pt II Ch XVII §5 (p 201).
10. ^ Fechner, G. (1876) Vorschule der Aesthetik. Leipzig: Breitkopf und Hartel. Website: chuoft.pdf
11. ^ Campen, Cretien van (1996). De verwarring der zintuigen. Artistieke en psychologische experimenten met synesthesie. Psychologie & Maatschappij, vol. 20, nr. 1, pp. 10–26.
12. ^ Galton F (1880). "Visualized Numerals". Nature. 21 (543): 494–5. doi:10.1038/021494e0.
13. ^ Galton F (1880). "Visualized Numerals". Nature. 21 (533): 252–6. doi:10.1038/021252a0.
14. ^ Galton F. (1883). Inquiries into Human Faculty and Its Development. Macmillan. Retrieved 2008-06-17.
15. ^ [Gazzinga, M.S (1970). The bisected brain. New York: Appleton-Century-Crofts]
16. ^ Fechner, Gustav (1876). Vorschule der Ästhetik. Leipzig: Breitkopf & Härtel. pp. 190–202.
17. ^ Wallis, K.F. (2014). "The two-piece normal, binormal, or double Gaussian distribution: its origin and rediscoveries". Statistical Science, Vol. 29, No. 1, pp.106-112. DOI: 10.1214/13-STS417 arXiv:1405.4995
18. ^ a b Levelt, W. J. M. (1965). Binocular brightness averaging and contour information. British Journal of Psychology, 56, 1-13. https://dx.doi.org/10.1111/j.2044-8295.1965.tb00939.x
19. ^ Robinson, T. R. (1896). Light intensity and depth perception. American Journal of Psychology, 7, 518-532. https://dx.doi.org/10.2307/1411847
20. ^ Ding, J., & Levi, D. M. (2017). Binocular combination of luminance profiles. Journal of Vision, 17(13, 4), 1-32. https://dx.doi.org/10.1167/17.13.4
21. ^ Pojman, Paul, "Ernst Mach", The Stanford Encyclopedia of Philosophy (Winter 2011 Edition), Edward N. Zalta (ed.)
22. ^ Nicholls, Angus; Liebshcher, Martin (24 June 2010). Thinking the Unconscious: Nineteenth-Century German Thought. Cambridge University Press. p. 272. ISBN 9780521897532.
23. ^ Freud, Sigmund (18 March 2015). The Interpretation of Dreams. Translated by A. A. Brill. Mineola New York: Courier Dover Publications. p. 35. ISBN 978-0-486-78942-2.
24. ^ Sulloway, Frank J. (1979). Freud: Biologist of the Mind.(pp. 66-67). Basic Books.
25. ^ Marshall, M E (1969), "Gustav Fechner, Dr. Mises, and the comparative anatomy of angels.", Journal of the History of the Behavioral Sciences (published Jan 1969), 5 (1), pp. 39–58, doi:10.1002/1520-6696(196901)5:1<39::AID-JHBS2300050105>3.0.CO;2-C, PMID 11610088
26. ^ For Hartshorne's appreciation of Fechner see his Aquinas to Whitehead – Seven Centuries of Metafysics of Religion. Hartshorne also comments that William James failed to do justice to the theological aspects of Fechner's work. Hartshorne saw also resemblances with the work of Fechner's contemporary Jules Lequier. See also: Hartshorne – Reese (ed.) Philosophers speak of God.
27. ^ Fechner, Gazetteer of Planetary Nomenclature, International Astronomical Union (IAU) Working Group for Planetary System Nomenclature (WGPSN)
28. ^ Kreuger, L. E. (1993) Personal Communication. ref History of Psychology 4th edition David Hothersal 2004 ISBN 9780072849653
29. ^ "Fechner Day 2018 – The International Society for Psychophysics". www.ispsychophysics.org.
30. ^ "FECHNER DAY 2018". fechnerdays Webseite!. Retrieved 18 January 2019.
31. ^ "Fechner Day 2017 — Welcome (index)". fechnerday.com. Retrieved 18 January 2019.