Behavioral inhibition (BI) is a term used to describe a temperamental disposition to respond with initial hesitation, avoidance, distress, or withdrawal in the face of unfamiliar people or novel situations and events. BI is one of many individual differences influenced by inherited neurobiology, fetal environment, or both, that form a temperamental disposition or tendency for how an individual responds to the environment. A temperamental style of responding is consistent across situations, stable over time, and visible relatively early in life.

BI can be described by responses observed in behavior or in biological systems. Behaviors include facial expressions, motor movements, and expressed language. Biological responses, derived from genetic or nongenetic origins such as prenatal factors that alter brain chemistry (e.g., infection, drug exposure), include reactivity in heart ...