Positron emission tomography (PET) was used to compare regional cerebral blood flow (rCBF) in young (mean 26 years) and old (mean 70 years) subjects while they were encoding, recognizing, and recalling word pairs. A multivariate partial-least-squares (PLS) analysis of the data was used to identify age-related neural changes associated with (1) encoding versus retrieval and (2) recognition versus recall. Young subjects showed higher activation than old subjects (1) in left prefrontal and occipito-temporal regions during encoding and (2) in right prefrontal and parietal regions during retrieval. Old subjects showed relatively higher activation than young subjects in several regions, including insular regions during encoding, cuneus/precuneus regions during recognition, and left prefrontal regions during recall. Frontal activity in young subjects was left-lateralized during encoding and right-lateralized during recall [hemispheric encoding/retrieval asymmetry (HERA)], whereas old adults showed little frontal activity during encoding and a more bilateral pattern of frontal activation during retrieval. In young subjects, activation in recall was higher than that in recognition in cerebellar and cingulate regions, whereas recognition showed higher activity in right temporal and parietal regions. In old subjects, the differences in blood flow between recall and recognition were smaller in these regions, yet more pronounced in other regions. Taken together, the results indicate that advanced age is associated with neural changes in the brain systems underlying encoding, recognition, and recall. These changes take two forms: (1) age-related decreases in local regional activity, which may signal less efficient processing by the old, and (2) age-related increases in activity, which may signal functional compensation.

In 2 experiments, the authors used a process dissociation procedure (Jacoby, 1991) to separately examine the effects of aging on automatic and consciously controlled memory processes. In Experiment 1, a group of young adults in either a full-attention or divided-attention condition were compared with a group of elderly adults on a fame judgment task. Both age and divided attention had a detrimental effect on consciously controlled memory processing but left automatic processing intact. In Experiment 2, the same age-related pattern was found using a more demanding forced-choice recognition paradigm. There has been a great deal of recent interest in dissociations between performance on direct and indirect tests of memory found with the elderly (for reviews, see Craik & Jennings, 1992; Light, 1991). Direct tests of memory, which ask people to report on a past event, reveal pronounced declines in memory performance with age. The elderly are impaired, relative to the young, on tests of free recall, cued recall, and recognition (e.g., Craik, 1986; Craik & McDowd, 1987; Light & Singh, 1987). In contrast, indirect tests of memory, which do not ask people to report on an event but require them to engage in some task that indirectly reflects the occurrence of that event, often do not reveal effects of aging. The elderly do not show significant memory deficits whether they perform perceptual identification tasks (Light & Singh, 1987), generate category exemplars in response to category names (Light & Albertson, 1989), or complete word stems or fragments (Light & Singh, 1987; Light, Singh, & Capps, 1986). These tasks are indirect because subjects are initially presented with items that serve as potential responses for the subsequent task but are not asked to think back to the earlier presentation during task performance. The dissociation in performance on indirect and direct tests shown by the elderly has been interpreted as evidence that indirect tests reflect a form of memory or processing that aging spares (e.g., Howard, 1983; Light & Singh, 1987). Although discussed in the aging literature under a variety of terms such as priming (Rose, Yesavage, Hill, & Bower, 1986), procedural memory (Mitchell, 1989), and implicit memory (Light & Singh, 1987), the general notion is that performance on an indirect test does not entail deliberate recollection (Light & Albertson, 1989). Instead, the characteristics attributed to the processes underlying indirect test performance are similar to those ascribed to automaticity. Automatic processing has been described as a fast process that consumes no attentional capacity, is under the control of stimuli rather than intention, and occurs without awareness (e.g., Hasher & Zacks, 1979; Posner &

In 2 experiments, the advantages of placing automatic and consciously controlled memory processes in opposition to study age-related declines in memory performance were examined. Drawing on the common memory failure of mistakenly repeating oneself, a task was designed in which participants had to rely on conscious memory (recollection) to avoid repetition errors. Recollection proved to be severely affected by aging; older adults showed significantly more repetition errors than did younger adults, even at very short retention intervals. These results contrast sharply with the small age differences found with a standard recognition test. Moreover, L. L. Jacoby's (1991) processdissociation procedure (Experiment 2) showed that automatic memory processes were unaffected with age and could support recognition performance in older adults. The advantages of the opposition procedure for studying memory in older adults relative to other measures are discussed.

We examined an approach aimed at training consciously-controlled recollection, introduced by Jennings and Jacoby (2003) , for its ability to replicate and generalize. A continuous recognition task, requiring recollection to identify the occurrence of repeated items over gradually increasing lag intervals (number of intervening items between the first and second presentation of a repeated word), was given to a group of older adults twice a week for three weeks. Pre-and-post training performance was assessed on multiple measures and compared with a recognition practice and no contact control group. Recollection training proved successful; accurate identification of repeated items increased across a lag interval of 2 to 18 intervening items. Post-training gains following recollection training were found on n-back, self-ordered pointing, source discrimination and digit symbol substitution, but not with reading span or the CVLT-II. No changes were identified in the other groups. Gains from recollection training seem to transfer successfully in older adults.