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Abstract:
Temporal prediction and preparation are essential for adaptive behavior. Temporal expectations can be generated based on various temporal structures, including rhythms and interval memory. The neural entrainment theory postulates that temporal prediction in rhythmic streams uniquely relies on phase-aligning internal neural oscillations to the external rhythm. However, in motor tasks, previous studies found similar behavioral benefits and similar magnitude of neural phase alignment for temporal predictions derived from intervals and rhythms, questioning the unique role of rhythms in these phenomena. Yet, if rhythmic entrainment acts at low-level sensory circuits, its unique effect might only be revealed under high perceptual load. Here we address this using a challenging perceptual discrimination task, in which visual target timing is either non-predictable, is on-beat with a rhythm, or matches a repeated interval. Examining the differential effect of temporal expectation on multiple levels of perception, we collect both “objective” performance measures and “subjective” visibility reports, a fundamental distinction in consciousness research that has been overlooked in the temporal attention field. In line with previous findings, both interval- and rhythm-based temporal expectation improves behavioral performance compared to the unpredictable stream. However, inconsistent with the idea that sensory phase alignment is unique to rhythm-based temporal expectation, we find a comparable performance improvement between the rhythm and interval conditions. Furthermore, in EEG, we find similar phase modulation of low-frequency oscillations as well as similar suppression of alpha activity across the two conditions, calling into question the unique role of rythmic structures in driving temporal expectations.
