Four-month-old infants were screened (N = 433) for temperamental patterns thought to predict behavioral inhibition, including motor reactivity and the expression of negative affect. Those selected (N = 153) were assessed at multiple age points across the first 4 years of life for behavioral signs of inhibition as well as psychophysiological markers of frontal electroencephalogram (EEG) asymmetry. Four-month temperament was modestly predictive of behavioral inhibition over the first 2 years of life and of behavioral reticence at age 4. Those infants who remained continuously inhibited displayed right frontal EEG asymmetry as early as 9 months of age while those who changed from inhibited to noninhibited did not. Change in behavioral inhibition was related to experience of nonparental care. A second group of infants, selected at 4 months of age for patterns of behavior thought to predict temperamental exuberance, displayed a high degree of continuity over time in these behaviors.

Behavioral inhibition refers to a temperament or style of reacting that some infants and young children exhibit when confronted with novel situations or unfamiliar adults or peers. Research on behavioral inhibition has examined the link between this set of behaviors to the neural systems involved in the experience and expression of fear. There are strong parallels between the physiology of behaviorally inhibited children and the activation of physiological systems associated with conditioned and unconditioned fear. Research has examined which caregiving behaviors support the frequency of behavioral inhibition across development, and work on the interface of cognitive processes and behavioral inhibition reveal both how certain cognitive processes moderate behavioral inhibition and how this temperament affects the development of cognition. This research has taken place within a context of the possibility that stable behavioral inhibition may be a risk factor for psychopathology, particularly anxiety disorders in older children. The current chapter reviews these areas of research and provides an integrative account of the broad impact of behavioral inhibition research.

Objective-Behavioral inhibition (BI), a temperamental style identifiable in early childhood, is considered a risk factor for the development of anxiety disorders, particularly social anxiety disorder (SAD). However, few studies examining this question have evaluated the stability of BI across multiple developmental time points and followed participants into adolescence-the developmental period during which risk for SAD onset is at its peak. The current study used a prospective longitudinal design to determine whether stable early BI predicted the presence of psychiatric disorders and continuous levels of social anxiety in adolescents. It was hypothesized that stable BI would predict the presence of adolescent psychiatric diagnoses, specifically SAD.Method-Participants included 126 adolescents aged 14 to 16 years who were first recruited at 4 months of age from hospital birth records. Temperament was measured at multiple time points between the ages of 14 months and 7 years. In adolescence, diagnostic interviews were conducted with parents and adolescents, and continuous measures of adolescent-and parent-reported social anxiety were collected.Results-Stable maternal-reported early BI was associated with 3.79 times increased odds of a lifetime SAD diagnosis, but not other diagnoses, during adolescence (95% confidence interval 1.18-12.12). Stable maternal-reported early BI also predicted independent adolescent and parent ratings of ongoing social anxiety symptoms.Conclusions-Findings suggesting that stable maternal-reported early BI predicts lifetime SAD have important implications for the early identification and prevention of SAD. Keywords temperament; behavioral inhibition; social anxiety disorderApproximately 15% to 20% of children can be classified as behaviorally inhibited during early childhood. This temperamental style involves the tendency to show signs of fear, reticence, or wariness in response to unfamiliar situations and to withdraw from unfamiliar peers. 1,2 Approximately half of all children categorized as extremely behaviorally inhibited continue to