Conscious updating is a rhythmic process

As the visual world changes, its representation in our consciousness must be constantly updated. Given that the external changes are continuous, it appears plausible that conscious updating is continuous as well. Alternatively, this updating could be periodic, if, for example, its implementation at the neural level relies on oscillatory activity. The flash-lag illusion, where a briefly presented flash in the vicinity of a moving object is misperceived to lag behind the moving object, is a useful tool for studying the dynamics of conscious updating. Here, we show that the trial-by-trial variability in updating, measured by the flash-lag effect (FLE), is highly correlated with the phase of spontaneous EEG oscillations in occipital (5-10 Hz) and frontocentral (12-20 Hz) cortices just around the reference event (flash onset). Further, the periodicity in each region independently influences the updating process, suggesting a two-stage periodic mechanism. We conclude that conscious updating is not continuous; rather, it follows a rhythmic pattern.