An EEGManyLabs study to test the role of the alpha phase on visual perception (a replication and new evidence)

Several studies have suggested that low-frequency brain oscillations could be key to understanding how the brain samples sensory information via rhythmic alternation of low and high excitability periods. However, this hypothesis has recently been called into question following the publication of some null findings. As part of the #EEGManyLabs initiative, we set out to undertake a high-powered, multi-site replication of an influential study on this topic. In the original study, Mathewson et al. (2009) showed that during high amplitude fluctuations of alpha activity (8-13 Hz), the visibility of a visual target stimulus depended on the time the target was presented relative to the phase of the pre-target alpha activity. Furthermore, visual evoked potentials (e.g., N1, P1, P2 and P3) were larger in amplitude when the target was presented at the pre-stimulus alpha peaks, which were also associated with higher visibility. If we are successful in replicating the results of Mathewson et al. (2009), we intend to extend the original findings by conducting a second, original, experiment that varies the pre-stimulus time unpredictably to determine whether the phase-behavioural relationship depends on the target stimulus having a predictable onset time.