Developmental patterns of anger from infancy to middle childhood predict problem behaviors at age 8

Anger is a central characteristic of negative affect and is relatively stable from infancy onward. Absolute levels of anger typically peak in early childhood and diminish as children become socialized and better able to regulate emotions. From infancy to school age, however, there are also individual differences in rank-order levels of anger. For example, although decreasing in absolute levels, some children may stay the same and others may increase in rank order relative to their peers. Although change in rank order of anger over time may provide unique insight into children's social development, little is known concerning variations in developmental patterns of anger from a rank-order perspective and how these patterns are related to children's behavioral adjustment. The current study (N = 361) used group-based trajectory analysis and identified 6 distinct patterns of parent-reported child anger by rank across 9 months to 7 years: low-stable rank, average-stable rank, average- decreasing rank, average-increasing rank, high- decreasing rank, and high-stable rank. Most children (65.1%) were in low- to average-rank groups. However, 28.2% and 6.7% of the children were in average-increasing and high-stable groups, respectively. Children in the high- stable group showed elevated levels of externalizing and internalizing problems at age 8 compared to children in the average-stable, average- decreasing, and high- decreasing groups. These findings help to clarify different patterns of anger development across childhood and how they may relate to later problem behaviors.