Musical interactions support early social connection, yet the behavioral and neural mechanisms underlying this process in live caregiver–infant settings remain incompletely understood. This talk integrates evidence on how the quality and communicative function of musical engagement shape mother–infant coordination across the first postnatal year.

Using EEG hyperscanning in 84 mother–infant dyads assessed at 3, 6, and 12 months, we examined live music-box play during natural free play, maternal gaze aversion, and temporally shuffled music. Disrupting the natural interaction altered maternal tempo, attenuated infant neural responses, and reduced interpersonal neural synchrony, whereas synchrony was consistently highest during natural musical free play.

Complementing these neural findings, 3D motion-capture recordings of mothers interacting with their infants revealed function-specific movement patterns during infant-directed music: side-to-side swaying characterized lullabies, while vertical bouncing characterized playsongs. These patterns could not be explained by tempo alone, were amplified by infants‘ presence, generalized across Italian and Canadian samples, and allowed adult observers from diverse cultures to infer song function from movement alone.

Together, these findings show that naturalistic musical interaction coordinates caregiver and infant behaviour and interpersonal communication. They highlight music and movement as integrated channels through which caregivers scaffold infants‘ early social and developmental experiences.