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Ayse P. Saygin, Chen Song, Bianca van Kemenade, Luke E. Miller, Geraint Rees, Bahador Bahrami; Unconscious Processing of Biological Motion. Journal of Vision 2014;14(10):1021. doi: 10.1167/14.10.1021.
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© ARVO (1962-2015); The Authors (2016-present)
Biological motion processing is critical for survival and social interaction, but whether processing of these stimuli can take place outside awareness is unknown. Point-light biological motion stimuli consisting of about a dozen markers attached to the limbs of an actor have been used for decades to study the perception of biological motion. Here, we investigated whether point-light walker (PLW) stimuli masked and rendered invisible by interocular suppression could nevertheless induce adaptation for subsequent unmasked target PLWs. In each trial, an adapter PLW was presented to one eye and a large number of moving dots to the other; when fused, the noise dots effectively mask the PLW. Observers were then presented with an unmasked target PLW and were asked to report as fast as possible the direction in which it is facing. In Experiment 1, we established that discrimination of the direction of consciously perceived PLWs was faster if they were preceded by a masked adapter PLW heading in the opposite direction, indicating unconscious biological motion stimuli could induce adaptation. In Experiment 2, we replicated and extended this result by showing that the effect depended on adapter duration. Whereas single frame (12ms) or 300 ms PLWs did not induce significant adaptation, 600 ms and 2350 ms invisible PLWs did. Control studies were administered for each experiment to ascertain the adapter PLWs were not consciously perceived by the observers. Overall, these data show that masked biological motion still receives processing, and more specifically, that adaptation for biological motion can occur outside of awareness.
Meeting abstract presented at VSS 2014
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