High Quality Content by WIKIPEDIA articles! Psychophysics is a discipline within psychology that investigates the relationship between physical stimuli and their subjective correlates, or percepts. Psychophysics has been described as "the scientific study of the relation between stimulus and sensation" or, more completely, as "the analysis of perceptual processes by studying the effect on a subject's experience or behaviour of systematically varying the properties of a stimulus along one or more physical dimensions". Psychophysics also refers to a general class of methods that can be applied to study a perceptual system. Modern applications tend to rely heavily on Ideal Observer Analysis and Signal Detection Theory.