Role of Mental Abilities and Conscientiousness in Explaining College Grades

This study investigates the roles of general mental ability ( g ), specific mental abilities ( s ), and conscientiousness in predicting college academic performance, as measured by self-reported college grade point average (GPA), using data from the Project TALENT dataset, a comprehensive longitudinal study of over 300,000 high school students. The research extends prior work by examining a large battery of 59 mental abilities tests, high school GPA, and a conscientiousness measure to predict college GPA among 35,446 participants who completed a five-year follow-up survey and obtained a bachelor’s degree. Results indicate that g and conscientiousness independently predict college GPA, with g demonstrating a strong criterion-related validity (observed correlation of .32 when excluding crystallized knowledge) and conscientiousness adding incremental validity (observed correlation of .17). However, specific mental abilities generally failed to provide incremental validity over g , with the notable exception of the Word Functions in Sentences test, which showed modest unique contributions. Contrary to expectations, mathematical knowledge did not add incremental validity over g , challenging prior findings. The study also tested the classic multiplicative model of performance (motivation × ability), but found no significant interaction between conscientiousness and g , suggesting independent effects. Additionally, high school GPA was found to mediate the relationship between g , conscientiousness, and college GPA, supporting its role as a key predictor. These findings align with industrial/organizational psychology research on job performance, reinforcing the dominance of g over specific abilities in academic settings. Despite limitations, such as the age of the data and reliance on self-reported GPA, the results underscore the importance of g and conscientiousness in college admissions and suggest that admissions tests derive validity primarily from measuring general cognitive ability rather than specific aptitudes. Future research should explore these predictors in earlier educational contexts.