Motion detection in interleaved random dot patterns: evidence for a rectifying nonlinearity preceding motion analysis

Mather, George and Tunley, Hilary (1995) Motion detection in interleaved random dot patterns: evidence for a rectifying nonlinearity preceding motion analysis. Vision Research, 35 (15). pp. 2117-2125. ISSN 0042-6989

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Three experiments examined direction discrimination in temporally interleaved random dot patterns. The stimulus consisted of two or more uncorrelated random patterns presented in a repeating temporal sequence, so that each pattern appeared only once every n frames, separated by uncorrelated patterns. Each pattern shifted either leftward or rightward at each re-appearance (all patterns shifted in the same direction in any one presentation). Subjects could specify shift direction correctly even when eight different patterns were interleaved, provided that the duration of each frame was brief. An explanation based on responses in first-order motion energy detectors tuned to low spatiotemporal frequencies (effectively summating the interleaved patterns over time) was tested using a stimulus in which each pattern inverted in contrast mid-way through each frame, Contrary to predictions based on temporal summation, performance with contrast-inverting patterns was only slightly lower than with non-inverting patterns. An alternative explanation was examined, based on responses in motion detectors that full-wave rectify image contrast before extracting motion energy. Computed responses from such detectors successfully predicted psychophysical performance with interleaved random patterns. Implications for models of motion analysis are discussed.

Keywords:article, contrast, human, human experiment, movement perception, normal human, prediction, priority journal, temporal summation, visual discrimination, visual stimulation, Discrimination (Psychology), Female, Male, Motion Perception, Optical Illusions, Pattern Recognition, Visual, Psychophysics, Support, Non-U.S. Gov't, Time Factors
Subjects:B Subjects allied to Medicine > B140 Neuroscience
C Biological Sciences > C830 Experimental Psychology
Divisions:College of Social Science > School of Psychology
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ID Code:16128
Deposited On:03 Dec 2014 14:45

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