Trajectory of heart period to socioaffective threat in shy children

Relatively little is known about the psychophysiological processes underlying the development of socioemotional vulnerabilities that are common among adolescents exposed to child maltreatment. Using a prospective, longitudinal design, we investigated whether trajectories of resting heart period (HP; a physiological correlate of stress vulnerability) across three visits (separated by 6 months) was associated with shyness (a type of socioemotional vulnerability) in adolescent females exposed to child maltreatment ( N = 55; Mage = 14.07 years). Adolescents’ resting HP across visits was best characterized by two latent trajectories: a stable high class (25.5%) and a stable low class (74.5%). The stable low HP trajectory was associated with higher shyness at Time 1 (T1), and HP trajectory moderated the association between T1 and Time 3 (T3) shyness. Females in the stable low HP trajectory demonstrated stability of shyness from T1 to T3, whereas T1 and T3 shyness were unrelated for females in the stable high HP trajectory. We also found that shyness at T1 and T3 was associated with greater levels of anxiety at T3. These findings illustrate heterogeneity in the developmental patterns of resting autonomic activity in adolescent females exposed to child maltreatment; such differences may influence the continuity of some traits linked with socioemotional vulnerability such as shyness.

Understanding heterogeneity in shy or inhibited children's risk for poor socioemotional adjustment can inform intervention targets. The present study considered temperament traits associated with approach and regulation that may alter trajectories away from internalizing behaviors and poor socioemotional competence among shy toddlers. Fifty-five 22-24-month-old children (22 boys) preselected for parent-reported shyness were observed during laboratory tasks designed to measure shyness, activity level, positive affect, and inhibitory control between January 2016 and January 2018. Basal respiratory sinus arrhythmia (RSA) was obtained for a subset of the sample from recordings of cardiac activity as toddlers watched a neutral video. Hierarchical regression analyses predicted internalizing and competence from activity level, positive affect, inhibitory control, and basal RSA, alone and in interaction with shyness, while controlling for child gender. Activity level was positively associated with internalizing behaviors, and inhibitory control and positive affect were negatively associated with internalizing behaviors. Importantly, shyness was associated with more internalizing behaviors among children low in inhibitory control or high in basal RSA, but not among children high in inhibitory control or low in basal RSA. Relations between temperament traits and socioemotional adjustment were specific to internalizing behaviors and did not generalize to competence. The present findings suggest that in toddlerhood positive affect and inhibitory control may serve as protective factors for shy children, lessening risk for internalizing problems, whereas high activity or greater basal RSA may forecast risk.

Although shyness is a ubiquitous phenomenon with early developmental origins, little research has examined the influence of prenatal exposures on the developmental trajectory of shyness. Here, we examined trajectories of shyness from childhood to adulthood in three groups (N = 254), with varying degrees of prenatal adversity as indicated by the number of stressful exposures: extremely low birth weight (ELBW; <1000 g) survivors prenatally exposed to exogenous corticosteroids (ELBW+S, n = 56); ELBW survivors not prenatally exposed to exogenous corticosteroids (ELBW+NS, n = 56); and normal birth weight (NBW, n = 142) controls. Multilevel modeling revealed that the ELBW+S individuals exhibited the highest levels of childhood shyness, which remained stable into adulthood. The ELBW+NS and NBW controls had comparably low levels of childhood shyness; however, the ELBW+NS individuals experienced patterns of increasing shyness, while NBW controls displayed decreases in shyness into adulthood. We speculate that individuals exposed to multiple prenatal stressors (i.e., ELBW+S) may be developmentally programmed to be more sensitive to detecting social threat, with one manifestation being early developing, stable shyness, while increasing shyness among ELBW+NS individuals may reflect a later developing shyness influenced by postnatal context. We discuss the implications of these findings for understanding the developmental origins and developmental course of human shyness from childhood through adulthood.