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Wendy Baccus, Olga Mozgova, James Thompson; Adaptation of early ERP responses to biological motion by both form and motion. Journal of Vision 2009;9(8):615. doi: 10.1167/9.8.615.
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© ARVO (1962-2015); The Authors (2016-present)
The apparent ease with which human observers recognize biological motion has led to considerable research into the perceptual and neural mechanisms underlying these processes. One component of biological motion that contributes to recognition is the local motion of different elements. Evidence also suggests that observers can detect biological motion when local motion cues are ambiguous or completely absent, as long as form cues are intact, suggesting that the configuration of the moving elements also plays a role in recognition. However, the relative contribution of form and motion, and the time course of their contribution to biological motion processing, has not yet been determined. Here we investigated the contribution and timing of form and motion processing to the adaptation of early visual event-related potential (ERP) responses to biological motion. Subjects (N = 15) were presented with an adapter consisting of either intact biological motion, scrambled biological motion, a static frame from the intact biological motion, or no adapter, for 3sec prior to a biological motion stimulus presented for 1.5sec. Results revealed that the P1 response increased in amplitude across all adaptation conditions relative to no adapter. After correcting for these P1 effects, results revealed that the amplitude of the N1 (“N1bm”) was reduced by all three adapters, with significantly greater adaptation in the intact biological motion relative to scrambled biological motion or the static frame. These results provide further support for the claim that the processing of biological motion requires the integration of form and motion cues. These findings also suggest that this integration occurs within the first 200ms of visual processing, possibly as part of a feedforward sweep of neural activity.
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