Exclusion Expected? Cardiac Slowing Upon Peer Exclusion Links Preschool Parent Representations to School‐Age Peer Relationships

Attachment theory proposes that children’s representations of interactions with caregivers guide information‐processing about others, bridging interpersonal domains. In a longitudinal study (N = 165), preschoolers (Mage = 5.19 years) completed the MacArthur Story Stem Battery to assess parent representations. At school‐age (Mage = 8.42 years), children played a virtual ballgame with peers who eventually excluded them to track event‐related cardiac slowing, a physiological correlate of rejection, especially when unexpected. At both ages, parents and teachers reported on peer and emotional problems. During exclusion versus inclusion‐related events, cardiac slowing was associated with greater positive parent representations and fewer emerging peer problems. Cardiac slowing served as a mediator between positive parent representations and peer problems, supporting a potential psychophysiological mechanism underlying the generalization of attachment‐related representations to peer relationships.