The ACT Predicts Academic Performance-But Why?

Scores on the ACT college entrance exam predict college grades to a statistically and practically significant degree, but what explains this predictive validity? The most obvious possibility is general intelligence-or psychometric " g ". However, inconsistent with this hypothesis, even when independent measures of g are statistically controlled, ACT scores still positively predict college grades. Here, in a study of 182 students enrolled in two Introductory Psychology courses, we tested whether pre-course knowledge, motivation, interest, and/or personality characteristics such as grit and self-control could explain the relationship between ACT and course performance after controlling for g . Surprisingly, none could. We speculate about what other factors might explain the robust relationship between ACT scores and academic performance.