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(Medical Xpress)—A team of researchers affiliated with several institutions in Finland has found that personality traits that convey economic advantages rose over a 15-year study period. In their paper published in Proceedings of the National Academy of Sciences, the group describes their study of data on a large portion of males born in Finland over the years 1962 to 1978 and what they found.

As the researchers note, prior research has shown that increases in intelligence levels have led to increases in incomes. In this new effort, they find that it appears the same is true for certain behavioral traits.

To learn more about how traits perceived as economically valuable have changed over time, the researchers obtained test results of 419,523 males (79 percent of the male population born during the test period) who took standard personality tests as they entered mandatory military service at age 20. The tests gauged the degree of eight traits in each testee: self-confidence, leadership, sociability, motivation, dutifulness, achievement striving, deliberation, activity-energy and masculinity. The researchers averaged the scores over the 15-year period and then made graphs showing how scores have changed. The graphs show a steady increase in all traits except for masculinity. This, the researchers claim, suggests that such positive traits have become stronger over time. This is important, they note, because in the second part of their study, they found that such traits led to higher incomes.

The second part of the study consisted of obtaining earnings data for the same group of test subjects at age 30 and then correlating what they found with scores on the personality tests. The resulting plots showed that all of the traits with the exception of masculinity led to increases in income.

The researchers note that the data period stopped after 1978 because the military changed the tests that were given to conscripts. Also, females were excluded from the study because women in Finland are not obliged to serve in the military as were 20 percent of males born during the study period who opted to perform civic service instead of military service or had medical absences. The researchers also point out that their study does not answer why such traits have been on the rise, though they note some possibilities might include growing up with fewer siblings, improvements in education and people migrating to cities.

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More information: Markus Jokela et al. Secular rise in economically valuable personality traits, Proceedings of the National Academy of Sciences (2017). Markus Jokela et al. Secular rise in economically valuable personality traits,(2017). DOI: 10.1073/pnas.1609994114 Abstract

Although trends in many physical characteristics and cognitive capabilities of modern humans are well-documented, less is known about how personality traits have evolved over time. We analyze data from a standardized personality test administered to 79% of Finnish men born between 1962 and 1976 (n = 419,523) and find steady increases in personality traits that predict higher income in later life. The magnitudes of these trends are similar to the simultaneous increase in cognitive abilities, at 0.2–0.6 SD during the 15-y window. When anchored to earnings, the change in personality traits amounts to a 12% increase. Both personality and cognitive ability have consistent associations with family background, but the trends are similar across groups defined by parental income, parental education, number of siblings, and rural/urban status. Nevertheless, much of the trends in test scores can be attributed to changes in the family background composition, namely 33% for personality and 64% for cognitive ability. These composition effects are mostly due to improvements in parents' education. We conclude that there is a "Flynn effect" for personality that mirrors the original Flynn effect for cognitive ability in magnitude and practical significance but is less driven by compositional changes in family background. Journal information: Proceedings of the National Academy of Sciences

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