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Andre Mascioli Cravo, Karin Moreira Santos, Marcelo Bussotti Reyes, Marcelo Salvador Caetano, Peter Maurice Erna Claessens; Endogenous alpha oscillations modulate the perception of causality . Journal of Vision 2014;14(10):1141. doi: 10.1167/14.10.1141.
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© ARVO (1962-2015); The Authors (2016-present)
The perception of causality is essential to help us understand how two events relate to each other. Central to causality is temporal contiguity: estimates of causality decrease as the interval between events increases, and for intervals longer than approximately 150 ms the events appear independent. It has been suggested that this effect might be due to perception relying on discrete processing. Previous work has shown that alpha oscillations (~10Hz) can modulate whether two sequential stimuli are perceived as sequential or simultaneous. However, whether a similar mechanism may modulate the perception of causality remains unknown. Here, we investigated whether the phase of ongoing alpha oscillations modulated the perception of causality. We used the classic launching effect proposed by Michotte with concurrent recording of EEG signal. In each trial a disk moved towards the center of the screen where it touched a central disk. After a certain delay the central disk began moving away. Observers (n=17) had to judge whether the first disk caused the movement of the second. The delay at each trial was chosen via a staircase procedure so that the majority of trials were around the point of maximum uncertainty for that participant. The point of subjective causality (PSC - the delay where participants had maximum uncertainty whether the events were causal) was of 123 ms Â± 13:45 (mean Â± sem). We found that fronto-central alpha phase at the moment in which the second disk started moving significantly modulated the PSC. Moreover, we found that alpha phase was concentrated around different angles in trials where participants perceived events as causal or not. We conclude that alpha phase plays a key role in modulating the sense of causality adding support to the notion that perception is discrete.
Meeting abstract presented at VSS 2014
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