Interpersonal neural synchrony and parent-child behaviors during naturalistic interactions: A systematic review

Interpersonal neural synchrony (INS), defined as the temporal alignment of neural activity between socially interacting individuals, has been proposed as an index of parent-child interaction quality. However, its relationship with moment-to-moment adjustment of parent-child behavior remains insufficiently understood. This systematic review examined associations between INS and observable behavior during naturalistic parent-child interactions, the factors influencing these associations, and the methods used to investigate them. Following PRISMA guidelines, systematic searches of Scopus, PubMed, and ScienceDirect identified 15 peer-reviewed empirical studies involving children from preschool age to early adolescence. INS-behavior associations were heterogeneous across studies. Higher INS was most consistently associated with mutual engagement, shared positive affect, and supportive parenting, whereas findings concerning reciprocity, responsiveness, and child agency were more context-dependent. Time-resolved analyses further indicated that INS fluctuated in relation to specific behavioral events and revealed temporally asymmetric patterns in which parent or child neural activity preceded that of the interaction partner. However, these patterns do not establish causal directionality and may partly reflect shared exposure to task-related or interactional inputs. Task structure and the availability of direct social cues appeared to shape INS-behavior associations, while parental stress and child social functioning emerged as potential sources of variability in INS. Methodologically, the findings highlight the value of combining micro- and macro-level behavioral coding with time-resolved and directionality-sensitive analyses, alongside stronger controls for spurious synchrony and common inputs. Given the limited number and methodological heterogeneity of available studies, the findings should be regarded as preliminary and primarily hypothesis-generating.