Weber-Fechner Law
Weber-Fechner Law
Basic law of psychophysics which expresses in quantitative terms the relation between the intensity of a stimulus and the intensity of the resultant sensation. E. H. Weber applying the method of “just noticeable difference” in experiments involving weight discrimination found that the ability to discriminate two stimuli depends not on the absolute difference between the two stimuli but on their relative intensities and suggested the hypothesis that for each sense there is a constant expressing the relative intensities of stimuli producing a just noticeable difference of sensation. Fechner, also employing the method of just perceptible difference, arrived at the formula that the sensation varies with the logarithm of the stimulus
S = C log R
where S represents the intensity of the sensation, R that of the stimulus and C a constant which varies for the different senses and from individual to individual and even for the same individual at different times. — L.W.