Age-related effects of practice and task complexity on card sorting.

Eight younger and 8 older women (17 to 25 and 62 to 75 years) practiced card sorting under timed conditions. Task complexity was varied by increasing the number of stimuli and by making sorting conditional on a second stimulus. The older women generally were slower, and age difference increased as a function of task complexity. Women of both ages responded at increasing rates over the five practice sessions. Gains were maintained during a follow-up test 10 days later and transferred to sorts with different stimuli. Practice did not reduce age differences (gains by the older women were matched by the younger ones), but there was some indication that the age-complexity relationship was attenuated.