Mather, George and Murdoch, Linda (1999) Second-order processing of four-stroke apparent motion. Vision Research, 39 (10). pp. 1795-1802. ISSN 0042-6989
Full content URL: http://dx.doi.org/10.1016/S0042-6989(98)00191-6
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|Item Status:||Live Archive|
In four-stroke apparent motion displays, pattern elements oscillate between two adjacent positions and synchronously reverse in contrast, but appear to move unidirectionally. For example, if rightward shifts preserve contrast but leftward shifts reverse contrast, consistent rightward motion is seen. In conventional first-order displays, elements reverse in luminance contrast (e.g. light elements become dark, and vice-versa). The resulting perception can be explained by responses in elementary motion detectors tuned to spatio-temporal orientation. Second-order motion displays contain texture- defined elements, and there is some evidence that they excite second-order motion detectors that extract spatio-temporal orientation following the application of a non-linear 'texture-grabbing' transform by the visual system. We generated a variety of second-order four-stroke displays, containing texture-contrast reversals instead of luminance contrast reversals, and used their effectiveness as a diagnostic test for the presence of various forms of non-linear transform in the second-order motion system. Displays containing only forward or only reversed phi motion sequences were also tested. Displays defined by variation in luminance, contrast, orientation, and size were effective. Displays defined by variation in motion, dynamism, and stereo were partially or wholly ineffective. Results obtained with contrast-reversing and four-stroke displays indicate that only relatively simple non-linear transforms (involving spatial filtering and rectification) are available during second-order energy-based motion analysis.
|Keywords:||article, contrast sensitivity, human, human experiment, information processing, luminance, movement perception, normal human, priority journal, psychophysics, vision, visual stimulation, Contrast Sensitivity, Depth Perception, Female, Humans, Male, Motion Perception, Optical Illusions, Pattern Recognition, Visual, Time Factors|
|Subjects:||B Subjects allied to Medicine > B140 Neuroscience|
C Biological Sciences > C830 Experimental Psychology
|Divisions:||College of Social Science > School of Psychology|
|Deposited On:||03 Dec 2014 13:44|
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