Self-Other Agreement in Personality Development in Romantic Couples
A large body of evidence indicates that personality traits show high rank-order stability and substantial mean-level changes across the lifespan. However, the majority of longitudinal research on personality development has relied on repeated assessments of self-reports, providing a narrow empirical base from which to draw conclusions and develop theory. Here, we (1) tested whether self- and informant-reports provided by couples show similar patterns of rank-order stability and mean-level change and (2) assessed self-other agreement in personality development. We charted the Big Five personality trajectories of 255 couples (N = 510; M age = 27.01 years) who provided both self- and partner-reports at 4 assessments across 1.5 years. Results indicated similar rank-order stabilities in self- and partner-report data. Latent growth curve models indicated no significant differences between self- and partner-reported personality trajectories, with exceptions to extraversion and agreeableness. We further found strong cross-sectional agreement across all Big Five traits and assessment waves as well as moderate self-other agreement in personality change in emotional stability and agreeableness. These findings highlight the relevance of multi-method assessments in personality development, while providing information about personality stability and change. Discussion focuses on the theoretical implications and future directions for multi-method assessments in longitudinal personality research.