Twentieth Century Intercohort Trends in Verbal Ability in the United States

Shawn F. Dorius, Duane F. Alwin, Julianna Pacheco

Sociological Science, June 13, 2016
DOI 10.15195/v3.a18

Vocabulary test score trends from the General Social Survey contradict the widespread conclusion that scores on standardized intelligence tests have systematically increased over the past century. We use a vocabulary test included in 20 nationally representative surveys administered since 1974 to test three hypotheses proposed to account for these trends, including changes in the formal measurement properties of the test, over-time changes in the meaning of education, and intercohort differences in exposure to words on the test. We find no support for the idea that test scores have declined because of changes in the structure of the test. Instead, our results show that education selectivity accounts for some cohort differences among prewar cohorts and that cohort-specific differences in exposure to words on the test account for nearly all variation in vocabulary scores of respondents born after 1945, suggesting different causal processes have influenced cohort verbal ability during distinct historical eras.

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Shawn F. Dorius: Department of Sociology, Iowa State University

Duane F. Alwin: Department of Sociology and Criminology, Pennsylvania State University

Julianna Pacheco: Department of Political Science, University of Iowa

Acknowledgements: This research was supported by National Institute of Child Health and Human Development Training Grant from the Population Studies Center at the University of Michigan (T32 HD007339). Duane Alwin was supported in part by a grant from the National Institute of Aging (R01AG021203), a grant from the National Science Foundation (SES-1331454), and the McCourtney endowment, College of the Liberal Arts, Pennsylvania State University, during the writing of this article. Please direct correspondence to Shawn F. Dorius (

  • Citation: Dorius, Shawn F., Duane F. Alwin and Julianna Pacheco. 2016. “Twentieth Century Intercohort Trends in Verbal Ability in the United States.” Sociological Science 3: 383-412.
  • Received: January 13, 2016
  • Accepted: January 28, 2016
  • Editors: Jesper Sørensen, Stephen Morgan
  • DOI: 10.15195/v3.a18

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