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Allison Allen, Nathan Heller, Nicolas Davidenko; Performed overt actions can disambiguate ambiguous apparent motion. Journal of Vision 2017;17(10):431. doi: 10.1167/17.10.431.
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Previous research has shown that ambiguous motion can be resolved in favor of the direction of a performed overt action (e.g., Wohlschäger, 2000). However, these studies have used paradigms in which the motion could only be disambiguated in one of two directions (e.g. clockwise versus counter-clockwise). Recently Davidenko and colleagues (Davidenko et al., VSS 2015, CogSci 2015) reported an illusion in which randomly refreshing pixel textures can elicit percepts of coherent apparent motion, referred to as illusory apparent motion (or IAM). One benefit to using IAM as a paradigm is that the random dots can be perceived as moving in any number of directions. The current study explores whether IAM can be used to study motion disambiguation by overt action. Subjects (n = 17) completed three blocks of trials. The stimuli consisted of a single static frame of random pixels that shifted either left or right by 4 pixels. To manipulate ambiguity, in low-noise trials 10% of pixels were randomly refreshed, versus 30% in medium-noise trials, and 100% in pure-noise trials. In the first two blocks, no action or a single button press was required to begin each trial. In the third block, subjects performed an overt action, pressing a left arrow, a right arrow, or an X (to indicate random/other) to begin each trial. After each trial, subjects reported the motion they saw by pressing a left or right arrow or an X. Our results indicate that during 10%-noise trials, subjects were no more likely to report motion consistent with their overt action than would be expected by chance (M = 31.6%, SE = 1.8%), whereas during 30%-noise trials this was significantly more likely (M = 39%, SE = 2.5%; t(16) = 240, p = .029). Our findings suggest that IAM is susceptible to disambiguation by performed overt actions.
Meeting abstract presented at VSS 2017
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