Quantitative theories of metacontrast masking.
In metacontrast masking, the effect of a visual mask stimulus on the perceptual strength of a target stimulus varies with the stimulus-onset asynchrony (SOA) between them. As SOA increases, the target percept first becomes weaker, bottoms out at an intermediate SOA, and then increases for still larger SOAs. As a result, a plot of target percept strength against SOA produces a U-shaped masking curve. Theories have proposed special mechanisms to account for this curve, but new mathematical analyses indicate that it is a robust characteristic of a large class of neurally plausible systems. The author describes 3 quantitative methods of accounting for the U-shaped masking effect and analyzes 4 previously published mathematical models of masking. The models produce the masking curve through mask blocking, whereby a strong internal representation of the target blocks the mask's effects.
Francis
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Department of Psychological Sciences, Purdue University, West Lafayette, Indiana 47907-1364, USA. gfrancis@psych.purdue.edu
D003071:Cognition / Q000502:physiology; D006801:Humans; D008960:Models, Psychological; D010470:Perceptual Masking; D011582:Psychological Theory; D013997:Time Factors; D014796:Visual Perception / Q000502:physiology