Early childhood aggression

Abstract

In this thesis the development, stability, and correlates of early childhood aggression were investigated. The normative development was examined in a general population sample using questionnaires completed by the parents of 12-, 24-, and 36-month-old children and again one year later. Results showed an early childhood aggression curve, with increasing rates of aggression in the second year of life and decreasing rates in the fourth year. One-year stabilities were moderate for 12-month-olds and high for 24- and 36-month-olds. In a subsample of mother-child dyads child physical aggression and parenting were observed from videotapes recorded when the children were 1-3 years old and again one year later. Results indicated that negative discipline was positively related to child aggression one year later, but only when mothers were low in initial sensitivity. Finally, a meta-analysis of the literature showed that basal cortisol levels are positively related to aggression in preschoolers, but that this relation is reversed in school-aged children. The association is stronger in children with clinical levels of problem behavior. This study sheds light on the normative course of early childhood aggression and its physiological and parental correlates.