Another possibility regarding the relation between ECF and impulsivity is that as adolescents mature, their ability to control impulsivity increases and is more readily observable across different facets of ECF. Research on the development of ECF suggests that cognitive control ability is not fully mature until age 15 and that working memory and reward processing continues to mature into young adulthood (Huizinga et al., 2006; Luciana, Conklin, Hooper, & Yarger, 2005). Perhaps these functions, especially cognitive control, are not sufficiently developed until mid-adolescence to slow down the increase in impulsivity that characterizes adolescence. Our results indicate that age was positively related to working memory and to Stroop performance. Although these functions were not strong enough to inhibit age related increases in impulsivity, they may gain in strength as the PFC matures. This may explain why the research program by Nigg and colleagues finds a relation between impulse control and drug use at ages 15 to 17 but not at ages 12 to 15 (Nigg et al., 2006).
