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).