Individual Differences in Response to Stress

Observation of newborns and infants reveals individual differences in reactivity to stress. A measurement system based on threshold, dampening, and reactivation is described to assess these individual differences in the newborn period and thereafter. The three features are independent and, therefore, represent different aspects of reactivity. There is some evidence for stability of individual differences in reactivity between birth and 2 months of age. This stability is more apparent for infants who were highly reactive as newborns. The role of dispositional factors of reactivity, their stability, and the effects of the environment are discussed.