Infant-Caregiver Object-Related Paired Actions as Communication Development

Human communication is grounded in social interaction, and infants begin to communicate before producing their first words. In interaction with caregivers, they engage in coordinated object-related activities that may develop into paired-action sequences. We studied the emergence of such sequences in eight infant-caregiver dyads observed during monthly laboratory visits across 6 months, beginning when infants were either 7 or 8 months old. During free play with age-appropriate toys, interactions were documented using microbehavioral manual coding, enabling detailed analysis of infant-initiated, object-related joint activities. A recurrent pattern involved infants throwing an object and caregivers responding by returning it, giving rise to throwing-and-passing sequences, sometimes accompanied by coordinated gaze. Due to the less scripted and less conventionalized nature of this sequence, we observed substantial variability across dyads and sessions. To complement behavioral description, we used computer vision-based tracking of infants' object-holding hand movements and identified developmental changes in movement kinematics, specifically decreases in speed and acceleration. Our documentation of the earliest infant-initiated, object-related joint activities demonstrates that the observed throwing-and-passing sequences represent early manifestations of paired-action sequences and include elements of intentional communication.