<P> Fluid intelligence , like reaction time , typically peaks in young adulthood and then steadily declines . This decline may be related to local atrophy of the brain in the right cerebellum . Other researchers have suggested that a lack of practice , along with age - related changes in the brain may contribute to the decline . Crystallized intelligence typically increases gradually , stays relatively stable across most of adulthood , and then begins to decline after age 65 . The exact peak age of cognitive skills remains elusive , it depends on the skill measurement as well as on the survey design . Cross-sectional data shows typically an earlier onset of cognitive decline in comparison with longitudinal data . The former may be confounded due to cohort effects while the latter may be biased due to prior test experiences . </P>
<P> Fluid intelligence , like reaction time , typically peaks in young adulthood and then steadily declines . This decline may be related to local atrophy of the brain in the right cerebellum . Other researchers have suggested that a lack of practice , along with age - related changes in the brain may contribute to the decline . Crystallized intelligence typically increases gradually , stays relatively stable across most of adulthood , and then begins to decline after age 65 . The exact peak age of cognitive skills remains elusive , it depends on the skill measurement as well as on the survey design . Cross-sectional data shows typically an earlier onset of cognitive decline in comparison with longitudinal data . The former may be confounded due to cohort effects while the latter may be biased due to prior test experiences . </P>
what happens to the crystallized intelligence as one goes from young adulthood to middle adulthood
what happens to the crystallized intelligence as one goes from young adulthood to middle adulthood
stays relatively stable
stays relatively stable