Becoming as Open-Minded and Organized as My Classmates? Peer Effects on Self-Reported Personality Trait Development in the Classroom.

Introduction: How does a student's personality development relate to the personality of their classmates? The school class builds a pertinent comparison group during adolescence that has been identified as a critical factor in students' development of abilities and self-perceptions. This study empirically tests the impact of classroom personality composition on changes in adolescents' Big Five personality traits. We hypothesized positive associations between class-level openness and conscientiousness and the individual development of these traits given their role in academic performance.

Method: To test these hypotheses and explore additional composition effects, we employed three approaches of multilevel structural equation modeling on two large longitudinal samples of German adolescents (N₁ = 5470; N₂ = 788).

Results: Our analyses yielded two principal findings: First, individual personality levels remained highly stable across different time periods. Second, contrary to our hypotheses, baseline class-level openness and conscientiousness were not positively linked to individual personality development. Instead, there were some indications that higher class-level openness was negatively linked to individual openness to experiences at the second measurement point.

Conclusions: We discuss the absence of systematic composition effects at the classroom level and consider methodological challenges in investigating these effects.