New research offers the most rigorous look yet at a question psychologists have debated for over a century: does intelligence determine what job you end up in? Using a large, nationally representative UK sample and small-area estimation techniques borrowed from survey statistics, the study ranks 360 occupations by average cognitive ability — and the pattern is striking. Physical scientists top the list with an estimated mean IQ of 114, while packers, bottlers, and fillers sit at the bottom around 87, a gap approaching two full standard deviations. Roughly a quarter of all variation in intelligence falls between occupations rather than within them (closer to a third for men and older workers), and people within the same occupation turn out to resemble each other more in IQ than in age or education level.
The researchers didn’t stop at cognition. They extended the same method to nine non-cognitive traits — the Big Five personality dimensions, risk tolerance, delayed gratification, self-efficacy, and mental health — and found a similar, though weaker, sorting pattern: less than 10% of variance in these traits is explained by occupation, with gaps between highest- and lowest-scoring professions ranging from about half a standard deviation (mental health) up to nearly 1.5 (openness to experience). Traits like delayed gratification, self-efficacy, openness, conscientiousness, and risk preferences also correlated meaningfully with occupational prestige and pay, though none as strongly as intelligence did.
Perhaps the most interesting wrinkle: occupations with more extreme average trait scores (very high or very low) tended to have less internal variation on that trait — as if certain jobs act as selective filters, admitting only people who fit a narrow profile. This pattern held clearly for cognitive ability and mental health, and more tentatively for other traits. The authors argue their findings support a “psychometric view” of occupational sorting — that ability and personality genuinely shape who ends up where in the labor market — while also flagging real questions about whether this stratification has weakened over time compared to older, less representative studies from decades past.
Link to full article: Redirecting