A general equation for sensory magnitude

Abstract

For the majority of experiments on sensory response, S. S. Stevens's power law provides a satisfactory description of the relationship between stimulus and sensory magnitudes. In its original form, it has proved to be inaccurate near the absolute threshold, when the sense organ is not in a neutral state of adaptation, when sensory noise is present, or when the sense organ is adapted to the particular stimulus under observation. This paper introduces a more general sensory law which also describes response under the conditions listed above. Stevens's power law is a special case of this more general equation. In this general formulation, sensory magnitude is considered to be the product of excitatory and inhibitory processes. Excitation can be described by power functions and inhibition by exponential functions. The general equation is applicable to response at both the electrophysiological and psychophysical levels. © 1982 Psychonomic Society, Inc.