A student can be extremely capable and still struggle to follow a difficult goal for years. Another can be less dazzling on a standardised test yet keep returning to the work long after the novelty has disappeared. Intelligence and persistence may help produce the same outcome, but they are not interchangeable.

That distinction sits inside one of the most discussed findings from Angela Duckworth’s early research on grit. In a small group of students at the University of Pennsylvania, higher SAT scores were associated with slightly lower self-reported grit. At the same time, grittier students had higher grade-point averages, including when SAT scores were statistically controlled.

It is a memorable pattern. It is also easy to turn into a bigger claim than the evidence supports. The value of the study lies in what it reveals about different routes to performance, not in a verdict that talent and perseverance oppose each other.

What Duckworth’s Penn study actually measured

The result appeared as Study 3 in the 2007 paper Grit: Perseverance and Passion for Long-Term Goals, written by Duckworth, Christopher Peterson, Michael Matthews and Dennis Kelly. The larger paper contained six studies, including adults, West Point cadets and National Spelling Bee finalists. The university result came from just one of them.

In autumn 2002, the researchers emailed an invitation to about 350 psychology majors at Penn. The paper describes 139 participants, 69 per cent of them women, although a summary table reports 138 for the grit measure. Participants completed an online Grit Scale and reported their current GPA, expected graduation year, gender and SAT score.

This was an unusually accomplished group. Its average SAT score was 1,415 on the scoring system then in use, which the authors said fewer than 4 per cent of test takers achieved. Calling the participants elite is therefore reasonable, but they were psychology majors at one selective university, not students sampled across several elite institutions.

The three correlations behind the headline

The study produced three numbers worth keeping together. Grit was positively associated with GPA, at r = .25. SAT was positively associated with GPA, at r = .30. Grit, however, was negatively associated with SAT, at r = -.20.

That last correlation is the intriguing part. Within this selected group, students with stronger SAT scores tended to describe themselves as slightly less gritty. The association was modest, not a neat division between brilliant but unmotivated students and diligent strivers. Plenty of individuals could have been high on both measures or low on both.

When the researchers statistically held SAT constant, the grit-GPA relationship increased to r = .34. Their summary table estimated that grit explained 6.3 per cent of the variance in GPA. That is meaningful for one short personality questionnaire, but it also leaves most of the differences in grades unexplained.

Why “ability taken into account” needs care

In this study, ability was represented by SAT score. Taking it into account meant calculating the association between grit and GPA after removing the linear variation connected with SAT. It did not mean matching students on every form of talent, prior knowledge or opportunity.

The SAT is not a pure reading of intelligence. It reflects learned knowledge, test familiarity, preparation and educational experience as well as reasoning ability. The authors followed earlier research in using it as a measure of general mental ability, but that choice does not turn one score into a complete map of a person’s capacity.

Nor does statistical control establish cause. The study was cross-sectional, with grit, GPA and SAT self-reported in the same online survey. Students were not randomly assigned to become more persistent. Course selection, study routines, health, financial pressure, prior schooling and many other unmeasured factors could contribute to both self-description and academic performance.

The compensation idea is plausible, not proven

Duckworth and her colleagues offered one possible interpretation for the negative SAT-grit link. Among people who are all relatively intelligent, those who are less bright than their peers might compensate by working harder and with more determination. The pattern is consistent with that story, but the study did not measure compensation or observe students changing their effort in response to their relative standing.

Selection also matters. At a university where nearly everyone has cleared a high admissions bar, the range of SAT scores is compressed. Relationships inside that narrow band may look different from those in the wider population. The authors explicitly warned that their high-achieving samples limited external validity and said they were hesitant to extrapolate to less talented populations.

So the finding does not show that higher ability generally produces lower grit. It shows a slight inverse association in one restricted sample. Treating that as a law would be exactly the kind of leap the paper’s limitations argue against.

Later research made the grit story more complicated

The idea of grit spread far beyond this Penn sample, and later work tested whether the construct was as distinctive and powerful as its reputation suggested. A 2017 meta-analysis covering 584 effect sizes, 88 independent samples and 66,807 people found that grit was moderately related to performance and retention, but very strongly related to the established Big Five trait of conscientiousness.

That review also found that perseverance of effort was more useful than consistency of interest, the other major component of the grit measure. Perseverance still explained some academic performance beyond conscientiousness, but the authors concluded that the higher-order grit construct was not clearly confirmed. A study of 4,642 British 16-year-olds similarly found that grit added little to academic prediction beyond traditional personality traits, especially conscientiousness.

Other researchers argue that persistence works best when it is attached to something a person genuinely values. A 2018 meta-analysis of 127 studies involving 45,485 people found larger grit-performance effects where participants were more passionate about the relevant domain. Silicon Canals has previously examined why the large meta-analyses deflate the simplest self-improvement story about grit.

Talent opens doors, persistence changes what happens next

The most useful conclusion is narrower than “grit beats talent.” Cognitive ability remains an important predictor of academic performance. In a much larger meta-analysis of 267 samples and 413,074 people, cognitive ability accounted for the largest share of the performance variance jointly explained by ability and the Big Five personality traits. Conscientiousness was the strongest personality predictor and remained robust after ability was considered.

Duckworth’s Penn result adds a human detail to that broader picture. Admission to an elite university gathers people who have already demonstrated substantial academic skill. It does not make them identical in how they organise effort, tolerate boredom, recover from setbacks or sustain attention across a semester. Those differences can still show up in grades.

Persistence is therefore not a substitute for talent, and talent is not a substitute for persistence. The two measures can make partly independent contributions, while their effects remain entangled with opportunity, environment, personality and the goal itself.

The headline pattern survives careful reading: in this particular group, higher SAT scores went with slightly less reported grit, while grit predicted GPA after SAT was considered. What does not survive is the simplistic moral. One small correlation cannot tell us that gifted people lack discipline or that effort always defeats ability. It tells us something subtler and more useful: the capacity to do the work and the tendency to keep doing it are different parts of achievement.