Neural Evidence for Implicit Processing of Rhythmic Syntax at Musical Cadences

Rhythmic syntax forms the temporal structural framework essential for musical meaning and emotion. While crucial for music perception, how rhythmic syntax is processed without direct attentional focus remains unknown. Using EEG, we examined this process by manipulating rhythmic syntactic regularity in cadence, comparing sequences ending on metrically strong positions (regular) and those with syncopated endings (irregular). Participants performed a pitch-detection task irrelevant to syntactic processing. The results showed that syntactic irregular endings failed to elicit a significant early right anterior negativity (ERAN), demonstrating the absence of automatic violation detection. In contrast, these violations robustly evoked a late P600, reflecting conscious structural processing of rhythmic syntax. Moreover, we used a deep learning method to confirm the EEG results and further validate the differential processing of regular and irregular rhythmic syntax in the brain. Our study provides direct neurophysiological evidence for the implicit processing of rhythmic syntactic violations in early and late stages.