Human Growth and Development / Unit 13 HGD 1828 worked example, 60 to 90 seconds
Crystallized and Fluid Intelligence at Midlife
The idea
Cattell's two intelligences follow different paths across adulthood. Crystallized intelligence, accumulated knowledge and vocabulary, shows continued increases through middle adulthood and holds into the sixties and seventies. Fluid intelligence, reasoning about novel problems, peaks in early adulthood, holds through middle adulthood, and declines in older adulthood. The Seattle study found vocabulary rising into the seventies, consistent with this pattern.
In practice
A fifty-five-year-old editor who knows more words than ever but takes longer than her young colleagues to master a new software system.
Where people slip
The misconception is that all intelligence declines in middle age. Crystallized abilities hold or rise, and practical problem solving improves. Exam items describe a task and ask which ability it draws on and how that ability changes with age: knowledge-based tasks point to crystallized intelligence, which holds up; novel reasoning to fluid intelligence, which declines later in life.
Your place on the trail
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