A motion illusion reveals the temporally discrete nature of visual awareness
Résumé
Quasi-periodic or “discrete” brain processes are, in theory, susceptible to a phenomenon known in engineering as “temporal aliasing.” When the rate of occurrence of events in the world is fast enough, the perceived direction of these events may be reversed. We have recently demonstrated that, because of a quasi-periodic attentional capture of motion information, continuously moving objects are sometimes perceived to move in the wrong direction (the “continuous Wagon Wheel Illusion”). Using a simple Fourier energy model of motion perception, we established that this type of attentional capture occurs at a rate of about 13 Hz. We verified with EEG recordings that the electrophysiological correlates of this illusion are restricted to a specific frequency band around 13 Hz, over right parietal regions – known for their involvement in directing attention to temporal events. We summarize these results and discuss their implications for visual attention and awareness.