Active Inference in Music Perception: Motor Engagement to Syncopation
Modulates Rhythmic Prediction Error
Abstract
In active inference, the sensory surprisal (a log-probability of sensory
data) of the prediction error between prediction and sensory input is
modulated by action. The urge to move (groove) induced by syncopation,
which provides metric prediction errors, can be considered a case of
active inference in music perception. The present study investigated
whether rhythmic prediction error is modulated by improving the
precision of rhythm perception through tapping in sync with the rhythm.
Thirty-five participants listened to a rhythmic sequence while tapping
two beats (tapping condition) or holding a pillow (no-tapping
condition), and electroencephalography (EEG) was recorded. In both
conditions, the timing of tone onset was rarely earlier (deviant: 20%)
than the standard (80%). The timing deviant elicited mismatch
negativity (MMN) in both the tapping and no-tapping conditions,
reflecting a prediction error in timing. Moreover, the MMN response,
weighted by precision, was larger in the tapping condition than in the
no-tapping condition. Neural entrainment was measured by calculating
intertrial phase coherence (ITPC), which reflects oscillatory activity
synchronized to stimulus frequency, and ITPC differed between the two
conditions at beat-related frequencies. These results suggest that
tapping enhanced meter and beat information, and reduced the sensory
surprisal of syncopation, resulting in a larger precision-weighted
prediction error. These effects were not due to physiological arousal
differences between conditions, as assessed by EEG power and heart rate
variability. This study provides evidence for the modulation of sensory
prediction error by bodily engagement within the active inference
framework.