Perceptual rhythms by phase-aligned perceptual performance peaks across trials.

Perceptual processing may rhythmically alternate. There is a line of evidence from dense sampling psychophysics supporting this claim: In such studies, performance in visual target detection or discrimination is repeatedly tested at various fine-grained time intervals relative to a reference event. This reference event is presented at the beginning of each trial, and it is thought to reset some internal oscillation. Performance time courses following the reset often show rhythmic oscillations in the sub-second range. The interpretation has been that several quickly alternating peaks and troughs of perceptual efficiency exist. Here, we propose an alternative. Instead of being rhythmic, the perceptual processing efficiency time course might exhibit only a single peak in each trial. If the temporal location of this peak is constrained to co-occur with one of the peaks of the internal continuing oscillation, rhythmicity in overall performance time courses can be explained when performance is computed across many trials. Applying this perspective to three published datasets (N = 44, N = 34, N = 11) and running simulations, we confirm the possible existence of such phase-aligned peaks in perceptual efficiency. We show that foreperiod priming (behavioural advantage of repeating the same time interval between reference and target from one trial to the next) alternates across time. This is predicted if peaks in perceptual efficiency are consistently allocated to those time intervals that coincide with a peak in the underlying oscillation. Priming therefore works best at these intervals, which coincide with a peak in the underlying oscillation.