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Christopher Blair, Gideon Caplovitz; Constraints on dynamical evolution of motion perception. Journal of Vision 2013;13(9):966. doi: 10.1167/13.9.966.
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© ARVO (1962-2015); The Authors (2016-present)
In their 2007 paper, Kanai, Sheth, and Shimojo demonstrated that observers were less sensitive to transient changes in moving objects if these changes occurred after the object had been in motion for >300ms. They posited that this was due to a shift from processing motion as individual frames to a gestalt percept. They further proposed a model in which spatiotemporal receptive fields align in response to the direction and speed of motion present over a time period of ~200ms. We sought to further test and extend these findings by examining the effects of repeated practice (does practice facilitate the establishment of the gestalt percept?) and motion path changes (does trajectory uncertainty disrupt the spatiotemporal receptive field) on participants’ ability to detect changes in a moving stimulus. Results indicated that with repeated practice, participants still showed a decline in the ability to detect transient changes in moving objects over time. However, this decline became attenuated with practice. Thus repeated exposure seems to weaken rather than strengthen the gestalt mode of perception. We also found that uncertainty in the motion trajectory did not improve transient change detection after 300ms or more of motion, as might be suggested by the previously proposed model. These findings suggest top-down factors related to practice and stimulus uncertainty likely contribute to the process of moving objects becoming gestalt percepts. Further, they call for an update to models based on the delayed alignment of spatiotemporal receptive fields.
Meeting abstract presented at VSS 2013
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