Multimodal correlates of socioemotional movie-watching explain internalizing symptoms across childhood and adulthood

Socioemotional skills emerge from coordinated behavioral, autonomic, and neural processes that continue to reorganize across development, yet how these systems jointly support emotion regulation and mental health remains unclear. Using a naturalistic movie-watching paradigm, we integrated behavioral, cardiac, and fMRI measures in children (6–14 years) and adults (18–30 years), alongside independent ratings of experienced valence and arousal. Across age groups, positive and negative emotional content elicited coordinated changes in subjective experience, heart rate, and corticolimbic activity, including engagement of the amygdala, hippocampus, and prefrontal cortex. Despite these shared patterns, marked developmental differences emerged. Children reported more positive affect, showed larger heart-rate deceleration, and exhibited stronger recruitment of thalamic and lateral prefrontal regions, consistent with more sensory-driven and effortful regulatory processing. Adults, in contrast, showed greater activation in hippocampal and posterior midline regions, suggesting increased reliance on memory-based and self-referential appraisal. During negative emotional content specifically, children preferentially engaged medial prefrontal regions, whereas adults showed enhanced lateral prefrontal recruitment, indicating a developmental shift from reactive to more deliberate emotion regulation. Importantly, models integrating behavioral, cardiac, and neural indices explained substantially more variance in internalizing symptoms than any single modality alone, highlighting the value of multimodal approaches for understanding developmental pathways to mental well-being.