Neural and behavioral signatures of feedback-based adjustment bias in response to infant cries.

Infant crying is a critical signal that prompts caregiving, yet the neurobehavioral mechanisms underlying how individuals adapt to feedback in this context are underexplored. Here, in 34 young adults (18 female; age from 19 to 26 years) with no prior caregiving experience, we used an infant cry feedback paradigm to characterize individual differences in behavioral adjustment and their neural correlates. Participants judged the cause of infant cries while their reaction time changes (ΔRT) and EEG were recorded. Our results revealed context-specific adjustment biases unique to infant cries, distinct from responses to animal vocalizations. Within the infant crying context, a negative-feedback bias (slowing after negative feedback) correlated with higher self-reported caregiving sensitivity, whereas a positive-feedback bias (slowing after positive feedback) correlated with lower caregiving motivation. Inter-subject representational similarity analysis (IS-RSA) further revealed a key asymmetry in neural responses, showing that higher negative-feedback bias was associated with greater inter-subject neural similarity during negative feedback (480-1000 ms) and positive feedback (600-700 ms), whereas higher positive-feedback bias was associated with more idiosyncratic neural patterns. Furthermore, a mediation analysis showed that the influence of the Late Positive Potential (LPP) on caregiving sensitivity was fully mediated by these behavioral adjustments, where lower LPP amplitudes predicted greater slowing after negative feedback, which in turn predicted higher intended infant caregiving sensitivity. These findings link specific behavioral adjustments to an asymmetric neural similarity structure, offering potential markers for caregiving dispositions and highlighting the importance of feedback processing in caregiver-infant interactions.