Is autonomic functioning distinctly associated with anxiety and unsociability in preschoolers?

There are many benefits of peer interactions for children's social, emotional, and cognitive development, and isolation from peers may have negative consequences for children. Although biological processes may underlie social withdrawal broadly, distinct patterns may be associated with withdrawal behaviors depending on their underlying motivation (e.g., shy versus disinterested). This study investigated the role of autonomic nervous system activity, as assessed via skin conductance level (SCL) and respiratory sinus arrhythmia (RSA) in predicting changes in unsociability (e.g., lack of interest in peers) and anxious-fearfulness (e.g., discomfort among peers). Data were collected using a community sample of 92 US preschool children (45.7% female; M_age = 45.51 months, SD_age = 3.81 months) at two time points one year apart. Gender differences were also explored. Baseline physiology was assessed while viewing a neutral video clip, and reactivity was assessed while viewing social exclusion and post-aggression discussion videos. For all children, coinhibition (i.e., SCL inhibition accompanied by RSA inhibition) to the post-aggression discussion video and blunted SCL activation to the exclusion video were prospectively associated with higher levels of anxious-fearfulness one year later. For boys only, baseline reciprocal sympathetic activation (i.e., SCL activation and RSA inhibition) was prospectively related to higher levels of unsociability one year later. For girls only, RSA inhibition in response to the post-aggression discussion video was prospectively related to higher levels of unsociability one year later. Findings contribute to a growing literature on autonomic reactivity in preschoolers' adjustment and suggest possible differences in the physiological processes underlying unsociability and anxious-fearfulness.