Memory

In summary, different theoretical mechanisms have been proposed to account for age differences in memory performance. Each mechanism has been shown to be important, and research is needed to better understand the relationship among the different constructs. It is becoming clear that no single mechanism can account for all age-related variance in memory performance, and future research will address the relationship among the mechanisms when predicting performance on different types of memory tasks. All of the theoretical mechanisms, however, assume that older adults have more limited processing resources.

One theme that has emerged from the discussion is that age differences in memory are determined by the degree of deliberate processing. Fergus Craik has suggested that memory performance is determined by an interaction between internal (self-initiated processing) and external (environmental support) factors (Zacks et al.). The amount of deliberate processing required in a task decreases as the task itself becomes more supportive. As mentioned earlier, a great deal more processing resources are needed to remember the words in a free recall task than in a recognition task. In a recognition task, the words themselves serve as retrieval cues and the processing required to recognize is minimal. No explicit cues, however, are provided in a free recall task, and the individual must engage in a great deal of self-initiated processing in order to retrieve the words. Age differences in recall therefore are much greater than age differences in recognition (Craik). As the amount of deliberate processing increases, age differences should increase; as the environmental support provided by the task increases, age differences should decrease.

There have been some research attempts to determine the extent to which a task requires deliberate processing versus the extent to which it relies on automatic processing. One such attempt is known as the "remember-know" procedure. After individuals correctly identify words in a recognition memory experiment, they are asked to estimate whether the word was deliberately recollected ("remember") or whether the recognition was based on familiarity, with no specific recollection of encoding the word ("know"). Several different experiments have found that older adults produce a smaller proportion of "remember" judgments for the words they recognize, and a greater proportion of "know" judgments (Zacks et al.). This finding implies a reduced ability to deliberately recollect the items at the time of test and a greater reliance on familiarity.

Another method for examining deliberate and automatic remembering has been developed by Larry Jacoby and his colleagues. The "process dissociation" procedure actually provides quantitative estimates of the deliberate and automatic processing requirements of different memory tasks. As an example of process dissociation, Jennings and Jacoby looked at age differences in recognition memory. Younger and older participants first looked at a list containing words that they simply read. Then they listened to a second list and were told they would be tested on the second list later. Following the two lists, they were given two different recognition tests. In both tests they were given pairs of words, one of which they saw earlier, either as a word they read in list 1 or as a word they heard in list 2. The second word in the pair was a new word they had not seen or heard previously.

On the first memory test, they were misinformed that one word in each pair had been presented auditorially in list 2, and the other word was either new or one that they read in list 1. They were to pick the word that they had heard in list two (exclusion test). If they picked a word that was presented in list 1, they could do that only through familiarity, because if they had recollected the word, they would have correctly rejected it because it was a list 1 word. In the second memory test, they were told that one word from each pair was a new item, and they were to pick the one they had either seen or heard before. In this case, their judgments could be based on either familiarity or recollection (inclusion test). By subtracting the estimate of recognition due to familiarity derived from the first test (exclusion) from the scores on the second test (inclusion), an estimate of recall based on recollection alone could be derived. The results showed that the age effects were limited to the deliberate recollection component of recognition memory. Estimates of familiarity showed no age effects. This analytical procedure provides further support for the conclusion that age effects are determined by the extent of deliberate processing required in a task.