Generational IQ: Quasilongitudinal insights from the Wechsler Adult Intelligence Scale, Fifth Edition

Cognitive changes throughout the lifespan have been explored through cross-sectional, longitudinal, and quasilongitudinal approaches. Much of this research indicates that cognitive abilities in the adult period have followed a typical pattern of decline, with sustained verbal intelligence (i.e., Verbal Comprehension Index) to later adulthood and steadily declining performance-based abilities (i.e., Visual Spatial Index, Fluid Reasoning Index, Working Memory Index, and Processing Speed Index) observed from early adulthood. Generational changes due to cultural and educational adaptations require us to explore cognitive aging as new tests are developed. Specifically, calls for examining the pathway of aging include both using up-to-date measures and strong research methodology, methodology controlling for practice effects and generational-related effects (i.e., a quasilongitudinal design). The present study explored cognitive aging with the newest version of the Wechsler Adult Intelligence Scale, the fifth edition, utilizing a quasilongitudinal approach. Findings indicate crystallized intelligence is maintained until ages 76-80, whereas processing speed immediately declines starting in the youngest age groups measured (i.e., those in their 20s). Visual spatial abilities and fluid reasoning skills age similarly, following a pattern of slow and steady decline. Working memory ages along with visual spatial and fluid reasoning until around ages 46-50, where it maintains skills longer with a slower rate of decline. Implications for practice are discussed, as well as future directions and limitations. (PsycInfo Database Record (c) 2026 APA, all rights reserved).