General intelligence and a strong work ethic are the best predictors of college grades

An analysis of the Project TALENT data (from the 1960s) found that general mental ability and conscientiousness were the best predictors of students’ college grade point average (GPA). Contrary to expectations, mathematical knowledge did not improve predictions above these two factors. The paper was published in Intelligence & Cognitive Abilities.

General mental ability is a broad capacity to learn, reason, solve problems, understand complex ideas, and adapt to new situations. It includes abilities such as verbal reasoning, numerical reasoning, memory, abstract thinking, and processing information efficiently. It predicts how quickly and effectively people can learn new material, make decisions, and perform complex academic or work tasks. Because of this, general mental ability is one of the strongest predictors of learning, training success, and overall academic performance of students.

However, it is not the only factor determining how a student performs in college. The personality trait of conscientiousness is another important predictor because organized, disciplined, and persistent students usually complete assignments and prepare for exams more consistently. Motivation also matters because students who value their studies and believe effort matters are more likely to invest time and energy. Other factors such as prior academic achievement, the capacity for self-regulated learning and socio-economic status are associated with academic achievement in college as well.

Study author Jeffrey M. Cucina and his colleagues explored how well a large battery of mental abilities tests, high school grade-point average, and a measure of conscientiousness can predict college performance, expressed as a college grade-point average (GPA). The authors hypothesized that general mental ability, rather than specific abilities, would predict college performance and that adding conscientiousness to the mix would further improve the accuracy of predictions.

They also expected that conscientiousness would interact with ability in a multiplicative way—where motivation exponentially multiplies the effects of ability. Finally, based on previous research, they expected that mathematical knowledge would offer predictive value beyond general cognitive abilities, and that high school GPA would act as a mediator between these traits and college success.

The researchers used data from Project TALENT, a comprehensive longitudinal study conducted in the 1960s and 1970s that tracked over 300,000 high school students. The current study focused on a subset of 35,446 participants who completed a follow-up assessment five years after high school, successfully earned a bachelor’s degree, and self-reported their final college GPA.

The researchers analyzed the participants’ high school GPAs, their college GPAs, conscientiousness scores, and the results of 59 distinct tests of mental abilities. These tests covered general mental ability, spatial abilities, general information, perceptual speed, memory, mathematical abilities, and others.

The results showed that general mental ability and conscientiousness independently predict college GPA. General mental ability was the stronger predictor, but prediction accuracy visibly improved when conscientiousness was included in the statistical model. Once general intelligence was accounted for, almost none of the specific ability tests offered additional predictive power—with the minor exception of a test measuring word functions in sentences. Contrary to the researchers’ expectations, mathematical knowledge did not make predictions more accurate.

Furthermore, the study found no multiplicative interaction between conscientiousness and general mental ability, meaning a strong work ethic and high intelligence contribute to college success independently rather than multiplying each other’s effects. The researchers also confirmed that high school GPA acts as a mediator: high intelligence and conscientiousness help students earn good grades in high school, which in turn strongly predicts high grades in college.

“These findings align with industrial/organizational psychology research on job performance, reinforcing the dominance of g [general mental ability] 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,” the study authors concluded.

The study contributes to the scientific understanding of factors driving academic performance. However, the data used in this study is over half a century old, and the study authors note there is a need to verify the results with newer data. Additionally, the reliance on self-reported college GPAs may introduce slight inaccuracies compared to official academic transcripts.

The paper, “Role of Mental Abilities and Conscientiousness in Explaining College Grades,” was authored by Jeffrey M. Cucina, Kevin A. Byle, and Scott K. Burtnick.