Trajectories of physical and relational aggression across early childhood: Relations with peer risk factors.

The goal of the current study was to examine trajectories of relational and physical aggression in early childhood and evaluate peer predictors of these trajectories (i.e., peer rejection, relational victimization, and physical victimization). The study spanned three-time points (T1 in the spring, T2 in the fall, and T3 in the spring) in early childhood (N = 300; 44.0% girls; M age  = 44.70 months, SD = 4.38; 3.0% African American/Black, 7.6% Asian/Asian American/Pacific Islander, 1.0% Hispanic/Latinx, 11.3% multiracial, 62.1% White, and 15.0% missing/unknown). Observations of peer victimization and teacher report of peer rejection were collected at T1, and teacher report of aggression was collected at all time points. Results from piecewise latent growth models demonstrated that both forms of aggression decreased from T1 to T2 as children entered a new classroom and increased from T2 to T3 as they remained in that classroom. The increase in physical aggression from T2 to T3 was only significant for boys. Peer rejection at T1 emerged as a predictor of both intercepts and slopes from T1 to T2, and physical victimization predicted the physical aggression intercept and physical aggression slope from T1 to T2. Children high on these peer risk variables had higher initial levels of aggression, followed by a greater decrease in aggression from T1 to T2. Results underscore the importance of studying incremental change in aggression in early childhood and suggest that children who experience negative peer treatment have greater fluctuations in aggression over time.