Correlation between cognitive ability and educational attainment weakens over birth cohorts
Across multiple measures of educational attainment, we find a steady long-term decline in the correlation of cognitive ability scores from conscription testing and educational attainment for males in Norway. The correlation remains moderate to strong in recent cohorts and cognitive ability remains coupled to educational attainment, but the clear trend indicates that educational attainment is weakening over time as a signal of cognitive ability. This observation together with the finding that we already find a very high correlation between educational attainment and cognitive ability for birth cohorts prior to educational reforms and the democratization of education, goes counter to the hypothesis that educational attainment increasingly aligns with individual level ability as educational opportunities are broadened. Essentially, it questions the presumed evolution from ascription to achievement as the guiding principle of success in post-industrial societies14. Ability scores come from tests at age 18–19, which has been shown to increase the correlation between intelligence and education compared to when cognitive ability is measured at an earlier age6. Yet, as this age of measurement was consistent across years, it should not impact the trend in the correlations.
Norway is arguably one of the contemporary societies where it is easiest to obtain higher levels of education. From a less developed educational system, school reforms in the 1960s increased compulsory schooling for everyone in Norway12. Since 1994, everyone has a legal right to a place in a high school program irrespective of their past performance. The tertiary education system is relatively open and universal financial aid is provided by the government. The heritability of educational attainment has been found relatively high in Norway and similar countries1. Hence, this is a context where we would expect a strong correlation between cognitive ability and educational attainment to emerge, reflecting a shift towards meritocratic hierarchies following from the expansion of mass education.
The Norwegian data indicates the opposite of the expected pattern: educational attainment is over time becoming weaker as a signal of the cognitive abilities. Although this can mean different things, it has implications for the interpretation and valuation of educational attainment as an expression of an underlying trait. As cognitive ability does not equate with merit, educational attainment could still potentially be a strongly meritocratic signal of some broader set of traits, but this bundle may have become increasingly weighted towards non-cognitive factors such as motivation, perseverance, and emotional intelligence, perhaps as a result of changing demands in the labor market15,16,17,18. Others nevertheless argue that the role of non-cognitive skills, such as personality, in predicting socio-economic success has been overstated and does not remotely match the predictive power or cognitive capability19,20.
An alternative, potentially more plausible explanation for our findings, is the nature of the changing educational and labor market. Education might have become substantially less selective, as educational expansions may have made it generally easier to attain longer education, regardless of cognitive ability. This was coupled with a diversification of educational fields, whereby occupations that previously did not require higher education, and that may require other abilities than cognitive skills, might increasingly require degrees. The increased decoupling of educational attainment and cognitive ability could also happen if new educational tracks emphasize practical skills and less abstract curriculums that make cognitive ability less important. This is especially relevant in Norway, where vocationally oriented tertiary institutions are offering a wide range of educational programs and are acquiring an important status next to universities21. They are nevertheless still mainly attended by students with lower average grades and they have lower rejection rates, which could make the achievement of high educational attainment less dependent on cognitive ability22. Drawing on signaling theory23, educational attainment may also have become a noisier signal over time if the cost required to complete higher education has fallen sufficiently. Employers will to a lesser degree be able to screen candidates by using their educational credentials, and demand for other signals will increase.
Finally, there are some limitations to our study. We would note that the cognitive ability test used at conscription has remained essentially unchanged since the test was developed in the early 1950s, which means that test items may have become outdated and function differently due to changes in social context (e.g., the introduction of calculators in school would give pupils less training in pen-and-pencil calculations required for the conscription test). In addition, we only had cognitive ability scores available for men, which does not allow us to say anything about the correlation for women. Although research has shown that intelligence does not relate differently to school success for boys and girls24, and we would hence expect to observe similar patterns for women, this should be tested explicitly in future research.
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