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Matthew Seifert, Howard Hock; Both Dedicated and Flexible Motion Detection Benefit From Interocular Integration. Journal of Vision 2015;15(12):1179. doi: 10.1167/15.12.1179.
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© 2017 Association for Research in Vision and Ophthalmology.
Motion perception is determined by changing patterns of neural activation initiated by spatiotemporal changes in stimulus features. These changing stimulus features may serve as input to systems dedicated to processing a specific type of feature, or to systems that flexibly compute motion from a variety of feature types. Spatiotemporally changing luminance detected by motion energy mechanisms is representative of such a dedicated system, while counterchange (oppositely signed changes in neural activation initiated by spatiotemporal changes in any feature) is representative of a flexible motion detection mechanism. Dedicated motion detection computations likely occur earlier in the visual system than more flexible ones, possibly before information from the eyes has been combined, raising the possibility that dedicated motion detection mechanisms may benefit less from dichoptic integration than more flexible mechanisms. Method. Two experiments compared dichoptic and monocular viewing of multistep apparent motion with varying frame durations. The monocular stimulus comprised one of the interleaved halves of the dichoptic stimulus. Experiment 1 utilized Kanizsa squares to create counterchange-based translating motion of an illusory square surface. Experiment 2 created apparent motion by sequentially incrementing the luminance of stationary, explicitly drawn squares. Results. Luminance-based motion perception was best for shorter frame durations, and counterchange-based motion perception was best for longer frame durations. Perception of motion improved with dichoptic viewing for both stimuli, as compared to monocular viewing. Discussion. Dedicated (motion energy-based), and flexible (counterchange-based) motion computations may occur at different stages in the visual processing stream, but both benefit from dichoptic integration. Flexible counterchange mechanisms are a likely basis for 3rd order motion perception (Lu & Sperling, 1995), and are well suited for the integration of information distributed to the two eyes. However, such integration is not a definitive indicator of 3rd order motion processing.
Meeting abstract presented at VSS 2015
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