Rhythms in Cognition: The evidence revisited

Abstract

Do humans perceive the world through discrete sampling of the sensory environment? Although it contrasts starkly with the intuition of a continuous perceptual flow, this idea dates back decades when brain rhythms were first suggested to work as periodic shutters. These would gate bouts of information into conscious perception and affect behavioural responses to sensory events. Seminal experimental findings have since largely confirmed brain rhythms as the neural implementation of periodic sampling. However, novel methods, improved experimental designs, and innovative analytical approaches show that the exact roles and functional significance of rhythmic brain activity for cognition remain to be determined. In re-visiting the evidence for rhythmic sampling, the contributions to this Special Issue gave a mixed picture: Studies testing for rhythmic patterns in behavioural performance largely supported the notion. However, at odds with previous results, most attempts to link behavioural outcomes with the phase of neural rhythms did not find supporting evidence. Also, contrasting earlier results, studies that used external sensory or electrical stimulation to control neural phase (‘entrainment’) failed to find support for rhythmic sampling in behavioural performance despite other research, included here, that reported neural indicators of entrainment. This Special Issue therefore points out interesting divides in the study of rhythmic sampling across different domains and highlights the importance of publishing negative findings and replications to improve our understanding of the role of rhythms in cognition.