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Generational IQ: Quasilongitudinal insights from the Wechsler Adult Intelligence Scale, Fifth Edition
Brittany A Dale1, Emily L Winter2, Wenjing Guo3
1Department of Special Education, Ball State University.
Developmental Psychology
|June 22, 2026
Summary
Cognitive aging shows crystallized intelligence remains strong until ages 76-80. Processing speed declines early, while visual-spatial, fluid reasoning, and working memory show varied decline patterns across adulthood.
Area of Science:
- Cognitive psychology
- Neuropsychology
- Gerontology
Background:
- Cognitive aging research traditionally shows adult cognitive decline.
- Verbal intelligence (Verbal Comprehension Index) is maintained longer than performance-based abilities.
- Need for updated measures and methodologies (quasilongitudinal) to study cognitive aging due to generational changes.
Purpose of the Study:
- To investigate cognitive aging using the latest Wechsler Adult Intelligence Scale (WAIS-IV).
- To employ a quasilongitudinal design to control for practice and generational effects.
- To identify specific patterns of decline across different cognitive abilities throughout adulthood.
Main Methods:
- Utilized a quasilongitudinal research design.
- Employed the Wechsler Adult Intelligence Scale, fifth edition (WAIS-IV) for cognitive assessment.
- Analyzed cognitive changes across different adult age groups.
Main Results:
- Crystallized intelligence (Verbal Comprehension Index) remained stable until ages 76-80.
- Processing speed (Processing Speed Index) declined from the youngest age groups (20s).
- Visual-spatial abilities (Visual Spatial Index), fluid reasoning (Fluid Reasoning Index), and working memory (Working Memory Index) exhibited distinct age-related decline trajectories.
Conclusions:
- Cognitive aging patterns vary significantly across different abilities.
- Processing speed is particularly vulnerable to early decline in adulthood.
- Crystallized intelligence demonstrates remarkable resilience into later adulthood, supporting the need for continued research with updated methodologies.
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