Supplement Video # 1: A video clip from the interpersonal movement phase. The infant shown here was in the interpersonal synchrony predictable beats condition.
Supplement Video # 2: An example of an infant who displays helping behaviour towards the experimenter during the clothespin task, followed by an example of an infant who does not display helping behaviour.
Supplement Audio # 1: The melody played for infants during the interpersonal movement phase in the predictable beat conditions.
Supplement Audio # 2: The melody played for infants during the interpersonal movement phase in the unpredictable beat conditions.
Supplement Stimuli: The GarageBand files for the melody and bounce instruction tracks in the even/uneven beat conditions.
Garage Band Files (zip)