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Sarah Cormiea, Maryam Vaziri-Pashkam, Ken Nakayama; Unconscious perception of an opponent's goal. Journal of Vision 2015;15(12):43. doi: 10.1167/15.12.43.
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© ARVO (1962-2015); The Authors (2016-present)
Humans are experts at reading others’ actions. They effortlessly navigate a crowded street or reach for a handshake without grabbing an elbow. This suggests real-time, efficient processing of others’ movements and the ability to predict intended future movements. We designed a competitive reaching task where two subjects faced each other separated by a plexiglass screen. Fingertip positions were recorded with magnetic sensors. One subject (Attacker) was instructed via headphones to tap one of two targets on the screen and the other subject (Blocker) was told to try to reach the same target as quickly as possible. Reaction times, measured as the difference in initial finger movement (finger launch) of Attacker and Blocker were fast (~150ms): much faster than reaction times to a moving dot projected on the screen (~250ms). This suggests Blockers use preparatory actions of Attackers to predict their goal before finger launch. Next, we videotaped an Attacker and projected the video onto the transparent screen. Blockers’ reaction times to the videos matched those to a real Attacker. In half the blocks we cut the preparatory information from the video. Blockers were ~120ms slower responding to cut videos, suggesting preparatory information is predictive ~120ms before finger launch. Finally we played the videos from the start to various times relative to finger launch and asked subjects to report the Attacker’s goal with button presses. Surprisingly when videos were cut at ~120ms before finger launch subjects’ accuracy was ~70%: significantly lower than the accuracy of arm movements in response to full videos (~98%). This suggests that in the arm movement task subjects utilize implicit information that is not consciously accessible in the button press task. Taken together, these results suggest participants in a competitive interaction have implicit or unconscious knowledge of the intentions of their partner before movement begins.
Meeting abstract presented at VSS 2015
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