Effects of repeated testing in a longitudinal age-homogeneous study of cognitive aging

Valgeir Thorvaldsson, Scott Hofer, Stig Berg, Boo Johansson

Research output: Contribution to journalArticle

19 Scopus citations


Estimates of gains related to repeated test exposure (retest effects) and within-person cognitive changes are confounded in most longitudinal studies because of the nonindependent time structures underlying both processes. Recently developed statistical approaches rely on between-person age differences to estimate effects of repeated testing. This study, however, demonstrates how retest effects can be evaluated at the group level in an age-homogeneous population-based study by use of a sampling-based design approach in which level and change of cognitive performance of previous participants, measured at ages 70, 75, 79, 81, 85, 88, 90, 92, 95, 97, and 99 years, were compared with performances of survivors of a representative sample identified and drawn from the same original population cohort but invited for the first time at age 85 with subsequent measurements at ages 88, 90, 92, 95, 97, and 99. The comparisons revealed a trend toward retest effects on two out of five cognitive measurements. The study demonstrates how a design-based approach can provide valuable insights into continuous learning processes embedded in population average aging trajectories that are not confounded with cohort and mortality-related selective attrition.

Original languageEnglish (US)
JournalJournals of Gerontology - Series B Psychological Sciences and Social Sciences
Issue number6
Publication statusPublished - Nov 2006
Externally publishedYes


ASJC Scopus subject areas

  • Geriatrics and Gerontology
  • Aging
  • Psychology(all)

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