The association between mothers' and daughters' positive affect is moderated by child cardiac vagal regulation.

Introduction Extensive research has supported the importance of children's positive affect in fostering prosperous psychosocial adjustment. Children's positive affect is believed to be significantly shaped by their environment in general and their caregivers' positive affect in particular. The current study investigates the role of child cardiac vagal regulation, a psychophysiological marker for social engagement, in shaping the association between maternal positive affect and child positive affect. Methods Mothers and daughters (n(dyads) = 28) participated in two experimental conditions. In the non-interactive condition, they separately drew a picture without interacting. In the cooperative condition, they drew a picture together. We measured child respiratory sinus arrhythmia (RSA), a widely used indicator of cardiac vagal regulation, during both conditions. We also coded maternal and child positive affect during the cooperative condition. Results Maternal positive affect was related to child positive affect, but only for children with medium-to-high tonic levels of RSA and RSA increases from non-interaction to interaction. Discussion Results suggest that child RSA plays a significant role in positive emotion socialization, by making children more susceptible to the emotional cues of their caregivers. Hence, child RSA should be taken into account in preventive and therapeutic efforts regarding child positive affect socialization.