Encoding strategies used by young and elderly adults in a keeping track task.

College students and older adults (mean ages 20.4 and 71.5 years) performed in a "keeping track" task that required them to recall, in response to probe questions, the most recently presented of each of a fixed set of categories. Questions alternated with presentations of new sets of items. Response accuracy, reaction times, and verbal reports provided information on the participants' strategies. The findings were consistent with the view (e.g., Hasher & Zacks, 1979) that older adults' poorer memory results from reduced use of effortful strategies. The older persons used fewer active encoding strategies than the college students and were less accurate and slower to respond. A subgroup of the elderly adults reported some active encoding activities; they performed more like the college students than the remaining elderly participants. A follow-up study in which college students were allowed reduced opportunity for active encoding produced performance intermediate between the other two groups.