Weber-Fechner Law
Steven's Power Law
A proposed relationship between the magnitude of a physical stimulus and the intensity or strength that people feel, suggesting the relationship between stimulus and perception is logarithmic.
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Origin
German physiologist Ernst Heinrich Weber conducted pioneering weight-lifting experiments in 1834, published in De Tactu, discovering that perceived differences in sensation depend on percentage changes rather than absolute differences. His student, physicist Gustav Theodor Fechner, formalized both laws in 1860 in Elemente der Psychophysik (Elements of Psychophysics), naming the first law after Weber. Fechner's law extended Weber's findings, proposing that sensation intensity increases logarithmically with stimulus energy.
Updated February 22, 2026