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Fechner-weber law --> Weber-Fechner law

The intensity of a sensation varies by a series of equal increments (arithmetically) as the strength of the stimulus is increased geometrically; if a series of stimuli is applied and so adjusted in strength that each stimulus causes a just perceptible change in intensity of the sensation, then the strength of each stimulus differs from the preceding one by a constant fraction; thus, if a just perceptible change in a visual sensation is produced by the addition of 1 candle to an original illumination of 100 candles, 10 candles will be required to produce any change in sensation when the original illumination was one of 1000 candles.

Synonym: fechner-weber law, webers law.