Anger Development from Infancy to Middle Childhood: Trajectories and Outcomes

Open Access
Author:
Liu, Chang
Graduate Program:
Psychology
Degree:
Master of Arts
Document Type:
Master Thesis
Date of Defense:
December 16, 2015
Committee Members:
  • Jenae Marie Neiderhiser, Thesis Advisor
Keywords:
  • anger development
  • individual variations
  • problem behaviors
  • group-based trajectory analysis
Abstract:
Anger is a central characteristic of negative affect in children. Studies of normative development have found that anger manifests in children during infancy, increases and reaches a peak between the ages of 2 and 4 years, and decreases steadily after the preschool period. When children enter school, most children are reasonably cooperative, however, a small group of children continue to show high levels of anger to caregivers and peers. The present study aimed to examine individual differences in the trajectories of anger in a sample of 361 adopted children followed from infancy (9 months) to age 7. A second aim was to clarify the developmental outcome of trajectory group membership with a focus on externalizing and internalizing problems in children at age 8. Group-based trajectory analysis identified six groups: low/stable, average/stable, average/decreasing, average/increasing, high/decreasing and high/stable. Most children (65%) were in low to average or moderate but decreasing anger trajectory groups (the low/stable, the average/stable, the average/decreasing, and the high decreasing groups) with levels of anger at average or below average at age 7. However, about 35% of the children showed moderate to high levels of anger between ages 4.5 to 7 years (the average/increasing and the high/stable groups), and were one standard deviation above average for anger at age 7. Children in the average/increasing and the high/stable groups showed significantly higher levels of externalizing problems at age 8 compared to the other four groups. Furthermore, children in the high/stable group showed significantly higher levels of internalizing problems at age 8 than the other groups except for children in the average/increasing group. Children in the high/stable group were not different from children in the average/increasing group in both externalizing and internalizing problems. This thesis is one of the first studies to report individual differences in the developmental trajectories of child anger from infancy to middle childhood. The findings from this report contribute to the literature seeking to distinguish between normative, age-related anger development, and potential problematic anger development that persists across childhood.