psychophysics

Branch of psychology concerned with the effect of physical stimuli (such as sound waves) on mental processes. Psychophysics was established by Gustav Theodor Fechner in the mid-19th century, and since then its central inquiry has remained the quantitative relation between stimulus and sensation. A key tenet has been Weber's law. Psychophysical methods are used today in vision research and audiology, psychological testing, and commercial product comparisons (e.g., tobacco, perfume, and liquor).

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