Stevens' power law

Stevens' power law is a proposed relationship between the magnitude of a physical stimulus and its perceived intensity or strength. It is widely considered to supersede the Weber-Fechner law on the basis that it describes a wider range of sensations, although critics argue the validity of the law is contingent on the virtue of approaches to the measurement of percieved intensity that are employed in relevant experiments.

Related Topics:
Magnitude - Weber-Fechner law - Measurement

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The theory is named after psychophysicist Stanley Smith Stevens (1906–1973). Although the idea of a power law had been suggested by 19th century researchers, Stevens is credited with reviving the law and publishing a body of psychophysical data to support it in 1957.

Related Topics:
Stanley Smith Stevens - 1906 - 1973

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The general form of the law is:

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: S = k I ^a

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where S is the intensity of sensation, k is a constant, I is the magnitude of the physical stimulus, and a is an exponent. The value of a is dependent on the type of stimulation.

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The table to the right lists the exponents reported by Stevens.

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