We first fit a model to test our measurement assumptions that cognitive control, reward processing, and working memory would underlie our assessments of these functions and their relations with age and gender. These tests indicated that although the four measures of working memory loaded on a single factor as expected, neither of the two cognitive control nor two reward processing assessments did so. Hence, in subsequent model tests, we treated these assessments as separately observed variables. In regard to impulsivity, sensation seeking and the two impulsivity indices loaded on a single factor as did the four risk behaviors. Furthermore, externalizing behaviors were strongly related to internalizing problems. Thus, we treated these variables as measures of a single underlying factor. As seen in Table 2, the loadings for each variable were significantly different from zero. It is also noteworthy that although both internalizing and externalizing problems loaded on a single factor, the externalizing score had a stronger loading than the internalizing score.
