Building on a number of studies that have documented mean-level changes in traits related to impulsivity and individual differences in these normative changes (e.g., Blonigen et al., 2008; Donnellan et al., 2007; Vaidya et al., 2008), the current study is the first to our knowledge to identify distinct trajectory groups of impulsivity across emerging and young adulthood (i.e., ages 18 to 35). Although these groups tended to exhibit modest, normative declines in impulsivity across time and maintain their initial rank-order positions, a nontrivial proportion of the current sample (9%) showed prominent decreases in impulsivity and marked changes in rank-order status in impulsivity. These findings further highlight the need of methodology that adequately models individual differences in change, as analyses that merely focused on rank-order consistency (see Roberts and Delvecchio, 2000) or mean-level changes of personality (see Roberts et al., 2006) would have “masked” the findings of marked and important developmental changes in impulsivity illustrated in this article (see Edmonds et al., 2007; Roberts and Mroczek, 2008, for more details regarding the implications of types of personality change).
