Instantaneous alpha
Samaha & Postle reported a correlation between instantaneous alpha and response on the flash fusion task, with correct responses being linked with a higher instantaneous alpha. Such an effect was not observed in the present study. We analysed electrodes that had the highest alpha amplitudes at the group level for both eyes-closed (B7) and pre-stimulus (C16) EEG-recording, and neither showed any time clusters within the -700 – 0 ms pre-stimulus window where instantaneous alpha frequency was significantly different for correct versus incorrect responses. Data from several other recent studies have also failed to support this link (Buergers & Noppeney, 2022, Ruzzoli et al., 2019). Though we have attempted to model our task as closely to Samaha & Postle’s as possible, there were some differences in our methodology which could potentially account for the discrepant results. For instance, from Samaha & Postle’s methods, it is not reported by how much the fixation cross decreased in luminance to prompt the participant of the upcoming stimulus. If this luminance shift was more drastic in our study, it could have caused a stronger phase reset effect, possibly nullifying any natural phase differences between trials (Harris, 2023).