80 0.8 0.6 90 0.4 - Emotional Stability Agreeableness Conscientiousness Cumulative d Value (Mean-Level Change) 0.2 0 10 20 30 40 50 60 70 80 Age Fig. 1. Cumulative mean-level change in three Big Five personality-trait domains, based on data from a meta-analysis of 92 longitudinal studies by Roberts, Walton, and Viechtbauer (2006). Mean-level change reflects the degree to which a population decreases or increases in specific traits over a specific period of time. These graphs were created by adding aver- age amounts of standardized mean-level change (d scores) from separate decades of the life course together, under the assumption that personality-trait change may be cumulative. Adapted from "Patterns of Mean-Level Change in Personality Traits Across the Life Course: A Meta-Analysis of Longitudinal Studies," by B. W. Roberts, K. E. Walton, and W. Viechtbauer, 2006, Psychological Bulletin, 132(1), p. 15. Copyright 2006 by the American Psychological Association. Adapted with permission. Bleidorn