Fechner, Gustav Theodor (g

s`täf tā`ōdōr fĕkh`nər), 1801–87, German philosopher and physicist, founder of psychophysics, educated at Dresden and Leipzig. He became professor of physics at Leipzig in 1834 but was forced by ill health to leave in 1839. Thereafter he devoted himself largely to the study of the relationship between body and mind, although under the name "Dr. Mises" he also wrote humorous satire. In philosophy he was an animist, maintaining that life is manifest in all objects of the universe. His greatest achievement was in the investigation of exact relationships in psychology and aesthetics. He formulated the rule known as Fechner's, or Weber's, law, that, within limits, the intensity of a sensation increases as the logarithm of the stimulus. Two of Fechner's most important works were Zendavesta (1851) and Elementen der Psychophysik (1860).

Fechner, Gustav Theodor

(born April 19, 1801, Gross Särchen, near Muskau, Lusatia—died Nov. 18, 1887, Leipzig, Ger.) German physicist and philosopher who founded the science of psychophysics. He taught at the University of Leipzig (1834–40) but left because of ill health. He developed experimental procedures, still useful in experimental psychology, for measuring sensations in relation to the physical magnitude of stimuli, establishing that, as physical stimulation increases logarithmically, sensation increases arithmetically. Most important, he devised an equation to express Weber's law. His principal scientific work was Elements of Psychophysics (1860).