A diffusion model of perceptual memory

A model is presented of the perceptual process through which an observer compares two consecutively observed stimuli. Emphasis is placed on the marmer in which a memory of the first stimulus is maintained until the comparison stimulus is observed. It is argued that the role of this perceptual memory process provides the primary distinction between detection and recognition tasks. Two experiments are reported: an experiment in which the observer is asked to judge the similarity in position of two points of light presented serially in a dark room; and an experiment in which the observer judges the similarity in loudness of two serially presented tones. The visual experiment is discussed in relation to the analysis of autokinesis and involuntary eye movements, while the auditory experiment is shown to have special relevance to the issue of time-order errors.