This is the 2007 version. Click here for the 2017 chapter 10 table of contents.

Age-Related Changes in Intellectual Functioning

Intellectual capabilities change as people grow older. IQ scores typically stay the same or get higher over the lifespan, although they may dip right before death (so called terminal drop). What changes most dramatically over the lifespan is not the overall quality of thinking but the speed of processing in some tasks (Bashore, Ridderinkhof, & van der Molen, 1998), the flexibility of learning, and the time of day when a person performs best.

What are some differences in the intellectual processes of young vs. old people?

May, Hasher, & Stoltzfus (1993) found a striking change in optimum time of day for intellectual activities, when comparing older and younger people. Older people typically described themselves as "morning people," saying their thought processes were clearest and sharpest in the morning. Of 210 young people in this study, none of them described themselves as "Definitely Morning" people, when the option of describing themselves as "Moderately Morning" people was available. Of 91 old people, none of them described themselves as "Definitely Evening" or even "Moderately Evening" people.

How do the differences in "peak time of day" affect performance?

These differences affect performance. When young and old people were compared on a variety of cognitive tasks in the morning (when old people were at their best) the two groups were identical in performance. When old and young people were tested in the evening, young people performed better.

What is "flexible" vs. "crystallized" intelligence?

Young people are generally superior to older people at flexible intelligence. They have an easier time learning new things or adapting to new circumstances. Older people are better at crystallized intelligence (Cattell, 1943). Older people have a large store of experience, which allows them to perform better in tests such as vocabulary tests that require an accumulation of knowledge in a specialized area. When older people are asked to adopt a new information processing strategy that is unfamiliar to them, they may be unable to do so.

What did Hunt discover about his older subjects?

The distinction between flexible and crystallized intelligence showed up in research by Earl Hunt. Hunt (1983) studied different strategies of problem solving and found that people formed distinct groups. Some (verbalizers) preferred to use language, and some (visualizers) preferred to use mental images. A revealing part of his research occurred when he asked the verbalizers to change their strategy. The task was simple and the strategy of the imagers is not difficult to describe: they just had to visualize a scene such as "The plus sign is over the star" then match it to a picture on a card.

Hunt found that all the college students he tested, even the ones who started out with the verbalizer strategy, were capable of adopting the imager strategy, and they benefited from it. Their scores went up. However, Hunt found that this mental flexibility declined with age. Some of the older subjects seemed to be unable to use imagery, even when the technique was recommended to them. Visualization ability declined with age, reaching a low in the oldest group, aged 56 to 67. In this group only 8 out of 17 subjects were able to use visual imagery in solving the problem. The 9 who could not use imagery were not able to switch to this strategy even when it was described to them and its advantages were pointed out. They had lost their flexibility of information processing.

How do the age-related changes affect job performance?

None of the age-related changes affect an older person's job performance. Slightly slower speed of processing is apparently offset by experience with the job. Only when old people are assigned new and unfamiliar tasks that emphasize speed (such as data-entry tasks on computers) are they less productive than young people...but even then, they tend to be more accurate (Azar, 1998).

Write to Dr. Dewey at

Don't see what you need? Psych Web has over 1,000 pages, so it may be elsewhere on the site. Do a site-specific Google search using the box below.

Custom Search

Copyright © 2007-2011 Russ Dewey