Changes in Fluid and Crystallized Intelligence Across the 20- to 90-Year Age Range on the K-Bit
Abstract
Changes in ability across the adult life span were investigated for the adult portion of the K-BIT standardization sample (500 individuals aged 20 to 90 years) to permit comparisons with the results of similar investigations conducted with the WAIS and WAIS-R. These changes were explored for separate measures of crystallized intelligence (Vocabulary) and fluid intelligence (Matrices). Two two-way ANCOVAs (age and gender) were conducted, in which raw scores on Vocabulary and Matrices served as dependent variables and educational attainment as the covariate. Results agreed with previous findings on the Wechsler scales: Crystallized intelligence basically was maintained across the age range, while fluid intelligence peaked early and declined steadily despite the control for education. Age x gender interactions were nonsignificant. This study showed that fluid intelligence seems to decline with increasing age, even when the test is untimated and does not rely on visual-motor coordination.
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Findings from Wechsler adult scales generalize to an array of IQ tests, whether comprehensive, brief, or group-administered.
“Though a great majority of investigations have been conducted with Wechsler’s individually administered adult scales, the findings generalize to an array of IQ tests, whether comprehensive (e.g., Kaufman and Horn 1996) or brief (e.g., Wang and Kaufman 1993), or administered in group format (e.g., Schaie and Hofer 2001; Kaufman and Horn 1996).”
From Cognitive Aging Revisited: A Cross-Sectional Analysis of the WAIS-5 (2025) · cites this paper as Wang and Kaufman 1993
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Skorupska, K., Nunez, M., Kopec, W., & Nielek, R. (2018) · Proceedings of the ACM on Human-Computer Interaction · doi:10.1145/3274428 · Cited by 23 · see citing works
Cognitive Aging Revisited: A Cross-Sectional Analysis of the WAIS-5
Winter, E. L., Dale, B. A., Maharjan, S., Lando, C. R., Larsen, C. M., Courville, T., & Kaufman, A. S. (2025) · Journal of Intelligence · doi:10.3390/jintelligence13070085 · Cited by 5 · see citing works
Self-citation
- Authors
- Wang, J.-J., & Kaufman, A. S.
- Affiliations
- American Guidance Service, Circle Pines, Mnnesota
- University of Alabama (US)
- Venue
- Journal of Psychoeducational Assessment
- Publisher
- SAGE Publications
- Published
- 1993-03
- Volume
- 11
- Issue
- 1
- Pages
- 29-37
- ISSN
- 0734-2829 (ISSN-L)
- 1557-5144
- OpenAlex
- W2054307921
- Cited by
- 90
- References
- 0
- Citations by year
- 2026: 6 · 2025: 5 · 2024: 1 · 2023: 2 · 2022: 7 · 2021: 4 · 2020: 5 · 2019: 6 · 2018: 6 · 2017: 4 · 2016: 5 · 2015: 2 · 2014: 1 · 2013: 2 · 2012: 2
- FWCI
- 1.03
- Type
- journal article
- Language
- en
- Open access
- closed
- Locations
- Journal of Psychoeducational Assessment (publishedVersion)
- Topics
- Social Sciences › Psychology › Experimental and Cognitive Psychology › Cognitive Abilities and Testing
- Social Sciences › Psychology › Neuropsychology and Physiological Psychology › Aging and Gerontology Research
- Social Sciences › Decision Sciences › Management Science and Operations Research › Psychometric Methodologies and Testing
- Keywords
- fluid intelligence, crystallized intelligence, adult lifespan, age differences, vocabulary, matrices, educational attainment, gender differences, cognitive aging
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