Beat-based and memory-based temporal expectations in rhythm: similar perceptual effects, different underlying mechanisms

Abstract

Predicting the timing of incoming information allows the brain to optimize information processing in dynamic environments. Behaviorally, temporal expectations have been shown to facilitate processing of events at expected time points, such as sounds that coincide with the beat in musical rhythm. Yet, temporal expectations can develop based on different forms of structure in the environment, not just the regularity afforded by a musical beat. Little is still known about how different types of temporal expectations are neurally implemented and affect performance. Here, we orthogonally manipulated the periodicity and predictability of rhythmic sequences to examine the mechanisms underlying beat-based and memory-based temporal expectations, respectively. Behaviorally and using EEG, we looked at the effects of beat-based and memory-based expectations on auditory processing when rhythms were task relevant or task irrelevant. At expected time points, both beat-based and memory-based expectations facilitated target detection and led to attenuation of P1 and N1 responses, even when expectations were task-irrelevant (unattended). For beat-based expectations, we additionally found reduced target detection and enhanced N1 responses for events at unexpected time points (e.g., off-beat), regardless of the presence of memory-based expectations or task relevance. This latter finding supports the notion that periodicity selectively induces rhythmic fluctuations in neural excitability and furthermore indicates that while beat-based and memory-based expectations may similarly affect auditory processing of expected events, their underlying neural mechanisms may be different.

Rhythm in speech and animal vocalizations: a cross‐species perspective

“…Research on timing and time perception is necessary but not sufficient to understand rhythm (for a parallel in music, see Ref. 10). In fact, timing research often focuses on the production or perception of individual time intervals.…”

Musical rhythm effects on visual attention are non-rhythmical: evidence against metrical entrainment

“…With this and similar paradigms, much evidence accumulated showing that humans are sensitive to and benefit from the temporal structure of stimulus streams not only in the auditory ( Chang et al., 2019 ; Bouwer et al., 2020 ) but also in the visual ( Rohenkohl and Nobre, 2011 ; Cravo et al., 2013 ) and tactile modality ( Jones et al., 2017 ; Jones, 2019 ). Moreover, the effect of rhythm was shown to transcend modalities, leading to the entrainment of modality-unspecific attending.…”

Expectancy-based rhythmic entrainment as continuous Bayesian inference

“…One specific question that the PIPPET framework might help resolve is how periodic and nonperiodic entrainment differ. PIPPET has no specific machinery to account for ways in which the two situations differ (for neural and behavioral evidence of differences between memory-based and periodicity based entraiment, see, e.g., [13, 5]. However, since it is sufficiently general to model both, it could guide an exploration of parameter differences between the performance of similar tasks in periodic and aperiodic contexts.…”

“…First, they are derived as optimal solutions to specific inference problems, and therefore all modeling decisions can be justified within a normative framework. Second, they are formulated in sufficient generality to describe entrainment based on non-isochronous and even aperiodic temporal expectations, an area that has lately received increasing experimental attention [6, 44, 45] but has been largely neglected in entrainment modeling. Third, they allow expectations to influence the inferred phase even in the absence of sensory events, creating the time-warping effect of disappointed expectations evidenced in humans by the “filled duration” illusion.…”

“…But although the behavior of these models may be satisfying, the groundwork underlying them is less so: key high-level concepts like the “attentional pulse” are difficult to define mechanistically, so the implementations of these concepts in models remain impressionistic. Moreover, recent results have emphasized the relevance and neural correlates of aperiodic modes of temporal expectation [12, 5, 13], but dynamic attending models are designed to describe entrainment to periodicity and cannot account for aperiodic forms of structured temporal expectation such as entrainment to memorized temporal patterns, irregular musical meters, and the loose temporal regularities of speech [14].…”