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Yuki Murai, Mauro Manassi, Bill Prinzmetal, Kaoru Amano, David Whitney; Serial dependence fluctuates at alpha rhythms. Journal of Vision 2018;18(10):1238. doi: https://doi.org/10.1167/18.10.1238.
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© ARVO (1962-2015); The Authors (2016-present)
To perceive the world as stable, our visual system tries to estimate it optimally based on the current sensory input and the past information. Serial dependence is a representative example of how the past forms the current percept: the perception of a stimulus is biased towards previously seen stimuli (Fischer & Whitney, 2014; Cicchini et al., 2014). In the present study, we investigated neural correlates of serial dependence using EEG. Because previous studies have demonstrated that alpha oscillations play an important role in visual encoding (Jensen et al., 2012), and the stimulus encoding may be an important factor in perceptual serial dependence, we hypothesized a link between alpha oscillations and serial dependencies in perception. In an experiment, a test face drawn from a continuous morph of facial identities was briefly presented, and then subjects adjusted a response face to match the test face. EEG signals were recorded while subjects performed the task. In the analysis, we sorted trials based on the phase of alpha oscillations at the precise moment the test face appeared, and calculated the magnitude of serial dependence (i.e., how much the current face appears pulled toward the faces seen in previous trials) separately for trials with different alpha phases. We found the serial dependence fluctuated periodically, depending on the alpha phase in frontal and occipital sites. In occipital sites, the serial dependence at 0 deg phase was 4-6 times larger than the serial dependence at 180 deg phase, and this relation was reversed in frontal sites. Permutation tests confirmed the significance of the observed periodic fluctuation in serial dependence. These results suggest that alpha oscillations are involved in the encoding of face information and modulate serial dependence in face perception. Serial dependence might reflect perceptual ambiguity of the stimulus, which could depend on the phase of alpha oscillations.
Meeting abstract presented at VSS 2018
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