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Matthew Seifert, Howard Hock; Counterchange, But Not Motion-Energy, Determined Motion Perception Integrates Dichoptically Presented Motion Information. Journal of Vision 2014;14(10):476. doi: https://doi.org/10.1167/14.10.476.
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© ARVO (1962-2015); The Authors (2016-present)
Visual motion perception is putatively a composite process enacted by different mechanisms that are sensitive to different types of information, and whose functions may be redundant depending on stimulus attributes. An important consideration in distinguishing between mechanisms is whether they can integrate information that is presented dichoptically (i.e., half of a motion sequence presented is presented to one eye, and the other inter-leaved half is independently presented to the other eye). Method. Two experiments compared the dichoptic presentation of six-step apparent motion stimuli (steps 1, 3, and 5 to one eye and 2, 4, and 6 to the other eye) to their monoptic viewing (either steps 1-3-5 or 2-4-6). In Experiment 1 the stimulus was a translating Kanizsa square (its edges were illusory contours); perceived motion was attributable to the detection of counterchanging activation (i.e., oppositely signed changes in activation at pairs of locations). In Experiment 2 the stimulus was a set of stationary literal squares whose luminance was sequentially incremented; perceived motion was attributable to the detection of motion energy. Results. The perception of motion was better for dichoptic than monoptic presentations of the translating Kanizsa squares. While motion could be perceived for faster speeds than the Kanizsa stimuli, there was little difference between dichoptic and monoptic presentations for squares whose luminance was sequentially incremented. Discussion. Information that was dichoptically presented to the two eyes was integrated for counterchange determined Kanizsa motion, but not for motion-energy determined spreading- luminance motion. The results are consistent with Lu and Sperling's (1995) characterization of 1st- and 3rd-order motion systems. Motion-energy determined spreading-luminance motion is fast and monocular (1st-order), whereas the counterchange determined motion of illusory surfaces favors slower speeds and benefits from integrating information presented separately to the two eyes. The latter supports counterchange as the mechanism underlying 3rd-order motion perception.
Meeting abstract presented at VSS 2014
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