Fig. 5: Developmental trajectories of peer relation quality and their association with a-priori trust and self-reported family adversity.

A The quality of peer relations (measured by self-report via the CFQ) increased from measurement time point 1 until 3. We plot posterior estimates and model-based errors (confidence intervals) from the mixed model based on n = 786 participants, using the function afex_plot (R package afex)⁶⁹. The box in the boxplot represents the middle 50% of the data, the line drawn through the box represents the median, the symbols represent the mean. The lower and upper edges of the box represent the first and third quartiles, respectively. B A priori trust at baseline (i.e., investments in round 1 of the multi-round trust task at T1) was positively correlated with peer relation quality (statistically significant main effect of T1 round 1 investment on friendships across all measurement time points). C Significant interaction of a-priori trust, longitudinal age and family experiences. Those with higher self-reported family adversity who showed a higher degree of a priori trust at baseline reported the strongest gain in peer relation quality (measured by the CFQ) over the longitudinal follow-up period. Longitudinal age was calculated with respect to age when the CFQ was completed (T1_q, T2_q, T3_q). The error band represents the standard error of the mean at each level of a priori trust.