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... Show moreIn 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. Show less
The general objective of this thesis was to test the effectiveness of an early intervention program aimed at reducing externalizing problems in 1- to 3-year-old children by enhancing parental... Show moreThe general objective of this thesis was to test the effectiveness of an early intervention program aimed at reducing externalizing problems in 1- to 3-year-old children by enhancing parental sensitivity and adequate discipline strategies. A new intervention was designed for this study: the Video-feedback Intervention to promote Positive Parenting and Sensitive Discipline (VIPP-SD) The study consisted of a screening phase in a general population sample (N = 2408) and a randomized case-control intervention phase in a selected subsample of children with high levels of externalizing behavior problems (n = 237). The results of this thesis show that externalizing problems occur in children as young as 1 year of age and are moderately predictive of externalizing problems one year later. Furthermore, child temperament appears to be a moderator in the association between maternal discipline strategies and externalizing problems. Children with difficult temperaments are more susceptible to both negative discipline (i.e., showing more externalizing problems) and positive discipline (i.e., showing less externalizing problems) compared to children with relatively easy temperaments. Finally, the VIPP-SD intervention was effective in improving maternal attitudes towards sensitivity and sensitive discipline, enhancing actual maternal sensitive discipline practices, and decreasing the children's level of overactive behaviors. Show less