Activation and update across the adult life span

In the present study activation and update, two processes which serve to increase memory efficiency, were measured for young and old adults. For older people, complaints about the ability to retrieve information from one's knowledge about the world are common. Yet empirical research provides conflicting evidence concerning whether long term memory retrieval declines in effectiveness with age. A possible explanation of the inconsistent findings is inefficient (time-consuming) retrieval. Inefficient retrieval could easily oe deleterious to performance on some retrieval tasks (especially timed ones), and it could interfere with one's day-to-day memory functions enough to give rise to complaints. Two memory efficiency processes were examined in the present study, activation, and update. Both processes speed the retrieval of selected concepts from semantic memory (one's knowledge store). Activation has short-lived effects which spread to concepts semantically related to concepts currently being processed. Activation improves memory retrieval efficiency by "anticipating" what informa tion in semantic memory will be needed in the very near future (that information which is semantically related to ongoing mental events) and temporarily speeding the retrieval of that information. Update, on the other hand, has relatively permanent effects. Although update is a relatively new object of investigationz it appears that upon each occasion a word or concept is processed, that word or concept is subsequently somewhat faster to retrieve. As a result the words and concepts which a person uses most frequently receive the most update (speed-ups) and are faster to retrieve. Thus, in theory, update makes frequently used concepts faster to retrieve than infrequently used concepts, thereby improving the efficiency of retrieval from semantic memory. In the present study, world-knowledge questions were presented visually. Response times were measured from the onset of the question to the subject's spoken answer. Verification questions (e.g. "Do wild kangaroos live in Australia?") were primed by previously presented, semantically related verification questions (e.g.z "Do wild koala bears live in Australia?"). Priming effects were measured after a short delay (up to 30 seconds, to measure activation effects) and after a long delay (about 30 minutes, to measure update effects). In this manner, activation effects (short delay) and uodate effects (long delay) were measured for twelve young (ages 22-29) and twelve old subjects (age 60 and above). In order to ensure comparability of young and old subjects, both groups were selected from Houston area public school teachers. Although the general response latencies were slower for older subjects than for younger ones, activation and update effects were nearly identical for the two age groups. Thus, two information processing mechanisms which are critical to efficient memory retrieval appear not to decline with age. Hopefully, as more studies like the present study are reported, negative stereotypes of the aging process will be weakened.