Next year, 2021, marks the 100th anniversary of the beginning of Lewis Terman’s Genetic Studies of Genius. This was a study of 1,528 children high-IQ children that spanned 74 years of physical, cognitive, and social development. Although the Genetic Studies of Genius is one of the most famous studies in psychology, its size (consisting thousands of variables collected across eight decades) means most people have a simplified understanding of the study.

To remedy this, I have compiled 10 little-known, but surprising, facts about the Terman longitudinal study.

#1

In midlife, 68.2% of men and 70.8% of women stated that they learned they were in the study by age 14, and a many sample members (41.1% of men and 52.1% of women) said participating in the study had positive impacts on their life (Oden, 1968, pp. 36-39). But, in their old age, “Early knowledge of being labeled as gifted was negatively related to participants’ appraisals of their life accomplishments in adulthood” (Holahan, in press, p. 1).

#2

Although the identities of the sample members are confidential, some have chosen to reveal their participation in the study or had their participation revealed posthumously. The list includes Norris Bradbury, Henry Cowell, Lee Cronbach, Edward Dmytryk, Ancel Keys, Irving Lorge, Shelley Smith Mydans, Jess Oppenheimer, and Robert Sears and his wife Pauline Snedden Sears, and Frederick Terman (son of Lewis). This is just the list of study participants who have Wikipedia pages, meaning their contributions are still considered noteworthy in the 21st century.

#3

A lot of fuss has been raised (for example, by Malcolm Gladwell in his bestseller Outliers) about the fact that two children screened for the study and rejected later won a Nobel Prize in Physics: Luiz Alvarez and William Shockley. Critics of IQ testing see this as evidence that intelligence tests are flawed But, given Terman’s sampling method and the extremely low base rate of winning a Nobel Prize are more likely to be the reasons that Alvarez and Shockley were not selected for the study (Warne et al., 2020). Their absence if a study of “geniuses” does not invalidate intelligence tests or the concept of giftedness.

Left to right: Luiz Alvarez, Lewis Terman, and William Shockley. All photos from Wikimedia Commons.

#4

It won’t be surprising that Terman’s high-IQ sample members were more educated than average. But what may be surprising is how educated they were. By their mid-30s, 69.8% of men and 66.5% of women had earned a bachelor’s degree (Terman & Oden, 1947, p. 149), even though the Great Depression began when the average sample member was 19–right when they would have been attending college. Even by modern standards, this is amazing; in 2017, only 34.2% of all Americans ages 25 or older had a bachelor’s degree (National Center for Educational Statistics, 2017, Table 104.10).

#5

In the 1980s, Robert Sears–who ran the study at the time and was himself a member of the Genetic Studies of Genius sample–discovered that some of the IQ scores calculated for sample members were incorrectly calculated. When his team used the original answer sheets to re-calculate IQ scores for the sample members, they found that the minimum IQ of sample members was no longer 135, it was 116 (for uncorrected IQs) or 106 (for corrected IQs). As far as I know, nobody has ever re-analyzed any of Terman’s findings using these IQ scores.

#6

The Terman sample members were long-lived, on average. Compared to the population born at roughly the same time and with very similar demographics, they lived approximately ten years longer (Duggan & Friedman, 2014, p. 501). Two of them even lived to be 104 years old. By comparison, life expectancy in the United States today is 78.9 years, about 6-8 years shorter than the average lifespan of a Terman sample member.

#7

The best predictor of longevity among the Terman sample members was the conscientiousness, a personality trait that is manifested in self-discipline, deliberation in making decisions, and dutifulness. This was a better predictor than self-reported physical activity, marital status, socioeconomic status, and other variables widely believed to cause people to live longer (Friedman & Martin, 2011).

#8

Some skeptics claim that Terman’s sample had high rates of positive life outcomes because they generally grew up in middle- and upper-class homes, not because of their high intelligence (e.g., Sorokin, 1956). A childhood. If childhood wealth were the main driver of adult accomplishment, then we should see some regression toward the mean in the Terman sample members when using childhood socioeconomic status to predict adult socioeconomic status. Instead, we see sample members climb to higher levels of socioeconomic status (on average) than the homes they were born into. Whereas the average home was modestly middle class, by 1955 (at an average of of 45), 96.3% of male subjects worked as professionals or semi-professionals (Terman & Oden, 1959, p. 74).

#9

Academic acceleration was much more common a century ago than it is today. At least 810 subjects (53.0%) experienced a full year of accelerated learning (i.e., a grade skip, early entry into elementary school, or early high school graduation) at some point in their K-12 experience. This may have resulted in long-term benefits for these people. Terman men who had an accelerated education earned an average of 3.6% to 9.3% more per year (Warne & Liu, 2017). This finding has been replicated with modern samples, though the income difference is weaker than in Terman’s sample (Warne, 2017). Grade skipping women in the Terman sample did not have an economic advantage over their high-IQ peers, but in more modern samples there is a correlation between academic acceleration and income in women.

Source: Warne & Liu, 2017, Figure 2

#10

The purpose of Terman’s longitudinal study was to examine the development of gifted children. Unfortunately, Terman undermined that goal by meddling in the lives of his subjects. He wrote letters of recommendation, gave advice to study participants, and helped some get into college (Shurkin, 1992). These actions have damaged the integrity of the study and make some of Terman’s conclusions questionable (Warne, 2019). On the other hand, replications of aspects of the Terman longitudinal study have shown that most of the results are sound (e.g., Bergold et al., 2020; Lubinski & Benbow, in press).

Conclusion

With findings spread out across 5 books, a monograph, and hundreds of articles, the Genetic Studies of Genius is a massive project, and it takes more than ten factoids to understand it completely. But given its influence in education, psychometrics, developmental psychology, personality, medicine, biology, and other areas (Hodges et al., in press), learning about the longitudinal study is a valuable use of time for scholars and practitioners in many fields.

References

Bergold, S., Wirthwein, L., & Steinmayr, R. (2020). Similarities and differences between intellectually gifted and average-ability students in school performance, motivation, and subjective well-being. Gifted Child Quarterly, 64(4), 285-303. https://doi.org/10.1177/0016986220932533

Duggan, K. A., & Friedman, H. S. (2014). Lifetime biopsychosocial rajectories of the Terman gifted children: Health, well-being, and longevity. In Simonton, D. K. (Ed.). The Wiley handbook of genius (pp. 488-507). Wiley-Blackwell.

Friedman, H. S., & Martin, L. R. (2011). The longevity project: Surprising discoveries for health and long life from the landmark eight-decade study. Hudson Street Press.

Hodges, J., Mun, R. U., Oveross, M. E., & Ottwein, J. K. (in press). Assessing the scholarly reach of Terman’s work. Gifted Child Quarterly.

Holahan, C. K. (in press). Achievement across the life span: Perspectives from the Terman study of the gifted. Gifted Child Quarterly. https://doi.org/10.1177/0016986220934401

Lubinski, D., & Benbow, C. P. (in press). Intellectual precocity: What have we learned since Terman? Gifted Child Quarterly. https://doi.org/10.1177/0016986220925447

National Center for Educational Statistics. (2017). Digest of educational statistics. Washington, DC: U.S. Department of Education. https://nces.ed.gov/programs/digest/2017menu_tables.asp

Oden, M. H. (1968). The fulfillment of promise: 40-year follow-up of the Terman gifted group. Genetic Psychology Monographs, 77, 3-93.

Shurkin, J. N. (1992). Terman’s kids: The groundbreaking study of how the gifted grow up. Little, Brown and Company.

Sorokin, P. A. (1956). Fads and foibles in modern sociology and related sciences. Henry Regency.

Terman, L. M., & Oden, M. H. (1959). Genetic studies of genius: Vol. V. The gifted group at mid-life: Thirty-five years’ follow-up of the superior child. Stanford University Press.

Warne, R. T. (2017). Possible economic benefits of full-grade acceleration. Journal of School Psychology, 65, 54-68. https://doi.org/10.1016/j.jsp.2017.07.001

Warne, R. T. (2019). An evaluation (and vindication?) of Lewis Terman: What the father of gifted education can teach the 21st century. Gifted Child Quarterly, 63(1), 3-21. https://doi.org/10.1177/0016986218799433

Warne, R. T., Larsen, R. A. A., & Clark, J. (2020). Low base rates and a high IQ selection threshold prevented Terman from identifying future Nobelists. Intelligence, 82, Article 101488. https://doi.org/10.1016/j.intell.2020.101488

Warne, R. T., & Liu, J. K. (2017). Income differences among grade skippers and non-grade skippers across genders in the Terman sample, 1936–1976. Learning and Instruction, 47, 1-12. https://doi.org/10.1016/j.learninstruc.2016.10.004

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