How Your Best Friend’s Personality Can Shape Your Own
In the first study of its kind, Ulf Zölitz shows how university students' personalities are shaped by their peers, with a lasting impact on their personal development.
In the first study of its kind, Ulf Zölitz, Professor of Economics of Child and Youth Development endowed by the Jacobs Center for Productive Youth Development, and his co-author Xiaoyue Shan from National University of Singapore, show how university students' personalities are shaped by their peers, with a lasting impact on their personal development. The study demonstrates that spending time with peers or friends who exhibit traits such as conscientiousness, openness, or competitiveness leads to long-term changes in the personality. These individuals, in turn, become more conscientious, open, or competitive. This suggests that peers and friends influence can be just as important as academic ability in shaping student outcomes – and even life trajectories.
Exploring Student Social Interactions
College is not only a place for academic learning but also for social interaction. Recognizing this, the authors conducted a randomized field experiment with undergraduate students. Prior to the study, the personalities of 1,229 students were assessed and categorized according to the Big Five traits: openness, conscientiousness, extraversion, agreeableness, and neuroticism. A measure of competitiveness was also included. Participants were then randomly assigned to four-person study groups in which they engaged in frequent study-related interactions over one semester. To assess the long-term effects, follow-up personality trait surveys were conducted for up to four years after the experiment.
Strong Evidence of Personality Trait Spillovers
The results revealed that students experienced personality “spillovers”: they became more conscientious, open, or competitive when grouped with peers who already possessed those traits. However, the researchers found no significant changes in extraversion, agreeableness, or neuroticism. One explanation is that conscientious peers increased the frequency of study-related interactions, reducing stress and anxiety in their group members. Students were especially likely to adopt traits from their peers that are beneficial in academic settings, such as conscientiousness and competitiveness. This supports the concept of “motivated personality change”, where individuals selectively internalize traits that help them succeed. These findings suggest that exposure to peers with productive personality traits can be just as influential as being surrounded by high-performing students.
Long-Term Implications and Policy Relevance
The long-term surveys confirmed that the spillovers in conscientiousness and competitiveness persisted for up to four years, while the effects of openness diminished over time. At the individual level, being aware of your peers’ and friends’ personality traits is crucial for your own personal development. At the collective level, personality spillovers have broader implications. This insight could be valuable for policymakers and educators who make decisions about group formation or class assignments, as well as for families choosing schools or neighborhoods. The results also raise important questions about whether economic and social preferences are similarly influenced by the peer environment. Future research could explore how peer groups shape these aspects of individual behavior.
