A fundamental principle in PSYCHOPHYSICS formulated in 1834 by Ernst Weber (1795–1878): the just noticeable difference (between two categorically similar stimuli) is proportional to the magnitude of the difference. Formulaically it is expressed...

A law of PSYCHOPHYSICS formulated in 1860 by Gustav Fechner: the perceived strength of a STIMULUS is a log function of intensity. Mathematically it is expressed as:   where A is perceived strength, I is intensity and It the threshold intensity....

A stimulus must increase geometrically (exponentially) if the response is to increase arithmetically (linearly). In the literature this is sometimes called Weber’s...

The Weber–Fechner law attempts to describe the relationship between the physical magnitudes of stimuli and the perceived intensity of the stimuli. Ernst Heinrich Weber (1795–1878) was one of the first people to approach the study of the human...