Age and ideal chunk size.

We tested young, middle-aged, and older adults for ability to organize six-letter sequences when these subjects were not externally induced to chunk the letter sets. In order to determine whether subjects would use optimal chunk sizes of two, three, or six letters, a serial recall task on which subjects were cued using digits was employed. From these data, the total number of correctly recalled sequences was computed, in addition to global and stop transitional error probabilities (TEPs). The results indicated that older adults recalled fewer correct sequences than did the young adults. However, both the global and stop TEP analyses demonstrated that all three age groups were chunking the six-letter sequences into two sets of three letters each. The present study (along with Allen & Coyne, 1988a, 1989) suggests that there are no appreciable age differences in functional chunk capacity, but that older adults exhibit poorer serial recall than younger adults.