Neural and behavioral correlates of sensorimotor synchronization to a subdivided beat: Evidence for a binary grouping advantage and musical training effects

Abstract

Motor synchronization is easiest when the metronome beats are subdivided into equal intervals. Here we combine electroencephalography (EEG) frequency-tagging and mismatch responses to examine how neural synchronization and predictive processing contribute to sensorimotor synchronization across four beat subdivisions: duplets (1:2), triplets (1:3), quadruplets (1:4), and quintuplets (1:5). We recorded EEG in musicians and non-musicians during a finger-tapping paradigm combining passive listening and synchronized tapping. Each trial had four sections: an isochronous beat, one of the four beat subdivisions, the beat again and the same beat subdivision. Only in the fourth section participants had to tap the beat while listening to the subdivision. We found that musicians outperformed non-musicians in the tapping task and showed stronger neural activity synchronized to the beat frequency and its harmonics for duplets, triplets and quadruplets. Importantly, non-musicians showed better tapping performance and stronger neural responses specifically for duplets only, indicating a sensorimotor synchronization advantage for the simplest binary subdivision. Mismatch responses to unexpected sound onsets likewise converged on the same pattern: listening to the first subdivision onset elicited smaller prediction errors for duplets in both groups, suggesting that binary subdivision better aligned with listeners' metrical expectations. Together, these findings show a correspondence between behavior and neural processes underlying the subdivision levels of the beat and highlight sensorimotor advantages for simple integer ratios that can be modulated by training in music. Both neural synchronization and predictive processes seem to jointly support this sensorimotor synchronization advantage for binary subdivisions.