The Origins and Heterogeneity of Shyness: A Developmental, Biological Perspective

Abstract

Temperamental shyness is a trait characterized by fear and avoidance in response to situations of social novelty and/or perceived social-evaluation. Although there has been an abundance of research examining the psychosocial correlates of childhood shyness, we know considerably less about the developmental and biological origins of shyness and its subtypes. Chapters 2 to 5 of this dissertation include empirical studies that examine the developmental and biological foundations of temperamental shyness in general, and Chapter 6 examines subtypes of shyness in particular. In Chapter 2, I found that individuals who were born extremely premature and also exposed to exogenous corticosteroids prenatally displayed a stable trajectory of high shyness from childhood to adulthood, possibly due to the programming of threat sensitivity. In Chapter 3, I found that children who had greater relative right frontal brain activity at rest (a neural correlate of fear and avoidance) demonstrated increases in shyness across the early school age years. In Chapters 4 and 5, I examined patterns of autonomic physiology among shy children during two types of social threat processing. I demonstrated that shy children show stability in autonomic arousal while viewing socio-affective threat from age 6 to 7.5 years (Chapter 4), and that shy children show arousal and excessive regulation on autonomic and affective levels during the anticipation of socio-evaluative threat (Chapter 5). Finally, Chapter 6 reports that the developmental onset of shyness is associated with distinct behavioral and biological correlates in shy children. Children with early-developing shyness showed greater relative right frontal brain activity at rest, while children with later-developing shyness showed greater salivary cortisol production to a socio-evaluative task. Collectively, the studies and findings from this dissertation highlight that shyness is related to distinct developmental and biological processes associated with avoidance and threat processing, which may underlie fear in novel social contexts.