A diffusion model of perceptual memory

Abstract

A model is presented of the perceptual process through which an observer compares two consecutively observed stimuli. Emphasis is placed on the manner 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 pr.imary 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 theanalysis of autokinesis and involuntary eye movements, while the auditory experiment is shown to have special relevanc e to the issue of time-order err ors.To distinguish a difference between two stimuli an observer must have a receptor or input process which will respond differently to the two stimuli. Furthermore, to compare two stimuli presented at different points in time, he must maintain a memory of the first stimulus until the second one occurs. For example, suppose an observer were asked to judge the similarity in loudness of two serially presented tones. A minimal requirement for accurate discrimination would be a receptor process which reacted differently to the two tone amplitudes. Furthermore, if the second tone occurred with some delay following cessation of the first tone, the observer would have to maintain a memory of the initial tone's loudness until he heard the second tone. Thus one might say that discrimination of serially observed stimuli is limited by at least two factors: one, the resolving power of the receptor or input process; and two, the efficiency of the memory process through which the observer retains information about one stimulus until the comparison stimulus occurs.Recent theoretical work on the psychophysics of detection has emphasized the role of the input process in determining sensory limits. The most prominent of these models is the psychophysical Theory of Signal Detection (see Green & Swets, 1966, for a comprehensive development of this theory). This is a twoprocess theory in that detection is represented as the product of two subprocesses, an input process and a decision or response process. The input proce ss specifies how the stimulus event evokes one of two sets of hypothetical sensory states in the observer; the decision process specifies how a given sensory state determines the observer's overt response. The particular sensory state evoked on each trial is treated as a value of a random variable whose distribution depends on the stimulus value. If two stimulus values evoke similar distributions of sensory states, it is difficult for the observer to distinguish which stimulus has given rise to a particular sensory state. His decision is assumed to be a statistical inference about the stimulus value based on his "sensory sample," the sensory state, and his knowledge o...

A Review of Capacity Limitation From Visual Perception to Short-Term Visual Memory of a Single Curved Contour

“…In accordance with the model developed by Kinchla and Smyzer (1967), Sakai and Inui (2002) produced a three-process model to predict recognition performance in STVM of curved contours ( Figure 2). In the first VP process, the amount of visual information that was encoded precisely with brief presentation was limited; in the second STVM process, memory for encoded features decayed with time; and in the third decision process, the observer's response criterion was a Gaussian random variable rather than a constant.…”

“…Memory noise has been identified as a cause of decay in STVM in the delayed discrimination of visual information such as that concerning line orientation (Vogels & Orban, 1986) and dot position (Kinchla & Smyzer, 1967). Memory noise corresponds to the variance of the value of the represented stimulus, which accrues in STVM.…”

“…Memory noise corresponds to the variance of the value of the represented stimulus, which accrues in STVM. In a model developed by Kinchla and Smyzer (1967), the stimulus value represented in STVM was a Gaussian random variable, with an expected value equal to the actual stimulus value, but the variance increased with the retention interval. This finding indicated that the cause of decay was not a decline in the represented value or convergence with a particular distorted value.…”

“…SDT has been used to predict recognition performance in delayed discrimination for visual information such as dot position (Kinchla & Smyzer, 1967) and line orientation (Vogels & Orban, 1986). Sakai and Inui (2002) proposed a model of recognition in STVM of curved contours (Figure 2) and examined the validity of the model via simulation.…”

“…By applying SDT to recognition memory of dot positions, Kinchla and Smyzer (1967) developed a model in which three processes (perception, memory, and decision) interacted to determine the relationship between stimulus and response. In accordance with the model developed by Kinchla and Smyzer (1967), Sakai and Inui (2002) produced a three-process model to predict recognition performance in STVM of curved contours ( Figure 2).…”