Differential distribution and lateralization of infant gestures and their relation to maternal gestures in the Face-to-Face Still-Face paradigm.

We examined whether there are differences in the lateralization of expressive gestures in infants during normal and stressful interactions with their mothers and the relations between their gestures. Thirty full-term 6-12 month-old infants were videotaped during the Face-to-Face Still-Face paradigm. We coded the occurrence and lateralization of infant self-directed and other-directed gestures and maternal proximal and distal gestures. Infant self-directed gestures increased from the Play to Still-Face episode and decreased from the Still-Face to Reunion episode. Other-directed gestures decreased from the Play to Still-Face and increased from the Still-Face to Reunion episode. During the Still-Face, self-directed gestures were predominantly performed with the left side of the body. Maternal gestures were not lateralized, but there was a prevalence of distal gestures in the Play and Reunion episodes of the paradigm. Left-sided infant other-directed gestures and left-sided maternal gestures were associated with each other. The findings highlight a differential utilization and lateralization of self- and other-directed gestures related to context and the stress experienced by the infant as well as to maternal gestures. These results are suggestive of a brain asymmetry, but an asymmetry related to emotional engagement and stress regulation.