Cognitive and neural effects of semantic encoding strategy training in older adults.

Prior research suggests that older adults are less likely than young adults to use effective learning strategies during intentional encoding. This functional magnetic resonance imaging (fMRI) study investigated whether training older adults to use semantic encoding strategies can increase their self-initiated use of these strategies and improve their recognition memory. The effects of training on older adults' brain activity during intentional encoding were also examined. Training increased older adults' self-initiated semantic encoding strategy use and eliminated pretraining age differences in recognition memory following intentional encoding. Training also increased older adults' brain activity in the medial superior frontal gyrus, right precentral gyrus, and left caudate during intentional encoding. In addition, older adults' training-related changes in recognition memory were strongly correlated with training-related changes in brain activity in prefrontal and left lateral temporal regions associated with semantic processing and self-initiated verbal encoding strategy use in young adults. These neuroimaging results demonstrate that semantic encoding strategy training can alter older adults' brain activity patterns during intentional encoding and suggest that young and older adults may use the same network of brain regions to support self-initiated use of verbal encoding strategies.

Proactive interference, accessibility bias, and process dissociations: valid subjective reports of memory.

Proactive interference was assessed with a variant of the process-dissociation procedure, which separates effects of habit (accessibility bias) and recollection (discriminability). In three cued-recall experiments, proactive interference was shown to be an effect of bias rather than an effect on actual remembering. Divided attention, age, and study duration selectively influenced the recollection parameter, whereas training probability selectively influenced the habit parameter. Furthermore, in Experiments 2 and 3, subjective reports of remembering were highly correlated with, and nearly identical to, objective estimates of recollection gained from the process-dissociation procedure. The authors discuss the relevance of the results to theories of proactive interference and argue that older adults' greater susceptibility to interference effects is sometimes caused by an inability to recollect rather than by an inability to inhibit a preponderant response.

Isolating the contributions of familiarity and source information to item recognition: a time course analysis.

Recognition memory may be mediated by the retrieval of distinct types of information, notably, a general assessment of familiarity and the recovery of specific source information. A response-signal speed-accuracy trade-off variant of an exclusion procedure was used to isolate the retrieval time course for familiarity and source information. In 2 experiments, participants studied spoken and read lists (with various numbers of presentations) and then performed an exclusion task, judging an item as old only if it was in the heard list. Dual-process fits of the time course data indicated that familiarity information typically is retrieved before source information. The implications that these data have for models of recognition, including dual-process and global memory models, are discussed.

Separating habit and recollection in young and older adults: effects of elaborative processing and distinctiveness.

An extension of L. L. Jacoby's (1991) process-dissociation procedure was used to examine the effects of aging on recollection and automatic influences of memory (habit). Experiment 1 showed that older adults were impaired in their ability to engage in recollection but did not differ from young adults in their reliance on habit. Elderly adults were also less able to exploit distinctive contextual information to enhance recollection. Experiments 2 and 3 showed that with more supportive conditions, older adults were able to benefit from distinctive contextual information. Quantitative and qualitative deficits in recollective abilities are interpreted within a dual-process model of memory. The problem of distinguishing between a deficit in recollection and a deficit in inhibitory processes in older adults (e.g., L. Hasher & R. T. Zacks, 1988) and the importance of this distinction for purposes of repairing memory performance are discussed.

Ironic effects of repetition: measuring age-related differences in memory.

Four experiments examined ironic effects of repetition, effects opposite to those desired (cf. D. M. Wegner, 1994). For an exclusion task, participants were to respond "yes" to words heard earlier but "no" to words that were read earlier. Results from young adults given adequate time to respond showed that false alarms to earlier-read words decreased with their repetition. An opposite, ironic effect of repetition was found for elderly adults--false alarms to earlier-read words increased with repetition. Younger adults forced to respond quickly or to perform a secondary task while reading words showed the same ironic effect of repetition as did elderly adults. The process-dissociation procedure (L. L. Jacoby, 1991, 1998) was used to show that factors that produce ironic effects do so by reducing recollection while leaving effects of repetition on familiarity unchanged.

Invariance in automatic influences of memory: toward a user's guide for the process-dissociation procedure.

Three experiments investigated assumptions of the process-dissociation procedure for separating consciously controlled and automatic influences of memory. Conditions that encouraged direct retrieval revealed process dissociations. Manipulating attention during study or manipulating study time affected recollection but left automatic influences of memory relatively invariant. However, paradoxical dissociations were found when conditions encouraged use of a generate-recognize strategy, violating assumptions underlying the estimation procedure. Use of subjective reports to gain estimates produced parallel results. Easily observed correlations are shown to be not useful for testing assumptions underlying the process-dissociation procedure. A multinomial model produced results that agree with those from the process-dissociation approach.

An opposition procedure for detecting age-related deficits in recollection: telling effects of repetition.

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) process-dissociation 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.

Separating habit and recollection: memory slips, process dissociations, and probability matching.

Memory slips are errors in performance that result when an automatic basis for responding (e.g., habit) opposes the intention to perform a specific behavior. Prior research has focused on factors that influence the probability of a memory slip while neglecting factors that facilitate performance. Using L. L. Jacoby's (1991) process-dissociation procedure to examine performance in both a memory-slip and a facilitation condition, the authors separated the contribution of habit and recollection (intentional memory) in a cued-recall task. The authors found that manipulating the strength of habit affected its contribution to performance in a manner that produced probability matching, but recollection was unchanged. In contrast, manipulations of presentation rate and response time influenced recollection but did not affect habit. Such dissociations support a model of memory in which automatic and intentional influences make independent contributions to performance.

Noncriterial recollection: familiarity as automatic, irrelevant recollection.

Recollection is sometimes automatic in that details of a prior encounter with an item come to mind although those details are irrelevant to a current task. For example, when asked about the size of the type in which an item was earlier presented, one might automatically recollect the location in which it was presented. We used the process dissociation procedure to show that such noncriterial recollection can function as familiarity--its effects were independent of intended recollection.

Dissociating automatic and controlled processes in a memory-search task: beyond implicit memory.

Our goal in this paper was to examine the processes that give rise to action slips. Procedures used to examine implicit memory and automatic processes were found to be unsatisfactory. However, the process-dissociation procedure proved useful for examining the contribution of the automatic and controlled processes underlying performance. The procedure was used in conjunction with a Sternberg memory-search task to examine the effects of set size, response speed, and stimulus-response mapping on controlled and automatic processes. The formulation allowed us to predict accurately how subjects would perform in a varied mapping condition. Moreover, set size and response speed were found to influence the controlled search process, but to leave the automatic influences unaffected. Stimulus-response mapping, on the other hand, was found to lead to probability matching in the automatic processes; this pattern was found to remain constant across changes in set size and response speed.

Dissociations of processes in recognition memory: effects of interference and of response speed.

Effects on two bases for recognition-memory judgements were examined using a process dissociation procedure (Jacoby, 1991). In three experiments it was found that increasing the length of a study list interfered with conscious recollection but left familiarity in place. Furthermore, an examination of reaction time distributions as well as results from a response-signal procedure showed that familiarity was faster as a basis for recognition judgements than was conscious recollection. However, both bases contributed to performance on the fastest as well as the slowest responses, suggesting that the two processes were acting in parallel.

Stroop process dissociations: the relationship between facilitation and interference.

L.L. Jacoby's (1991) "process dissociation procedure" was used to quantitatively estimate the contributions of color-naming and word-reading processes to responding on the Stroop task. The results show that color naming and word reading can operate independently to determine responses. Degrading stimulus colors eliminated the typical asymmetry between Stroop facilitation and interference, as predicted by the equations (Experiments 1 and 2). Degrading stimulus colors reduced the estimated contribution of color naming to responding but had no effect on the estimated contribution of word reading (Experiment 2). In contrast, increasing the proportion of incongruent items reduced the estimated contribution of word reading but had no effect on the estimated contribution of color naming (Experiments 3 and 4). The results indicate that the facilitating and interfering effects of automatic processes cannot be accurately measured in terms of differences from baseline.

Toward a redefinition of implicit memory: process dissociations following elaborative processing and self-generation.

Does conceptual processing affect unconscious uses of memory? We used a process-dissociation procedure to separate automatic (unconscious) and consciously controlled uses of memory in a stem-completion task. Contrary to results from indirect test conditions, estimates derived from our procedure showed no effect of self-generation and no differential effect of semantic and nonsemantic study conditions on automatic uses of memory. These results provide evidence that (a) indirect tests are often contaminated by conscious uses of memory and (b) stem completion is highly dependent on prior perceptual (and perhaps lexical) processing. The experiments demonstrate the advantages of using process-dissociation procedures over comparisons between direct and indirect tests.

Unconscious perception: attention, awareness, and control.

Conscious perception is substantially overestimated when standard measurement techniques are used. That overestimation has contributed to the controversial nature of studies of unconscious perception. A process-dissociation procedure (L. L. Jacoby, 1991) was used for separately estimating the contribution of conscious and unconscious perception to performance of a stem-completion task. Unambiguous evidence for unconscious perception was obtained in 4 experiments. In Experiment 1, decreasing the duration of a briefly presented word diminished the contribution of both conscious and unconscious perception. In Experiments 2-4, dividing attention reduced the contribution of conscious perception while leaving that of unconscious perception unchanged. Discussion focuses on the measurement of awareness and the relation between perception and memory.

Automatic versus intentional uses of memory: aging, attention, and control.

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.

Episodic effects on picture identification for alcoholic Korsakoff patients.

Experience with degraded pictures produces better subsequent identification of these pictures in amnesic patients. To examine the contribution of episodic memory to this facilitation, we compared identification of pictures that were identical to a studied picture, pictures that shared the same name with a studied picture, and new, unstudied pictures. In an initial phase of the experiment, patients clarified each picture until they could name it. During a second phase, they again clarified each picture and judged whether it was identical, similar (same-name), or different from pictures identified in the first phase. Korsakoff patients, as well as alcoholic controls, identified identical pictures faster than same-name pictures, and these in turn were identified faster than new pictures. The Korsakoff patients did show less facilitation than the alcoholic controls, but this difference was eliminated by testing the alcoholics after a week delay. The smaller facilitation in performance shown by amnesics and by alcoholics tested after a delay was accompanied by impaired recognition memory as well as by qualitative differences in recognition performance. The Korsakoff patients tended to label same-name pictures as different while alcoholic controls tested immediately called them identical, a tendency which disappeared when alcoholics were tested after a delay. These findings suggest that Korsakoff patients are influenced by specific episodic information even more than are alcoholic controls.

Fluency versus conscious recollection in the word completion performance of amnesic patients.

To examine the relative contribution of fluency and recollection to the word completion performance of amnesics, we administered a task in which patients were told specifically not to utilize previously presented words during stem completion (an Exclusion condition). This condition was contrasted with a standard word completion task in which patients were encouraged simply to complete the stem with the first word that came to mind (an Inclusion condition). Since the exclusion condition necessitated controlled respecification of the initial presentation, it was hypothesized that amnesics would be less able than controls to exclude study list items. Consistent with this hypothesis, the results indicated that the amnesics' performance, unlike that of the alcoholic controls, did not significantly differ as a function of task condition. To examine whether amnesics' conscious recollection could be enhanced, Experiment 2 presented the study list five times. The amnesics now were able to exclude a significant number of items from the study list; however, they still did so considerably less frequently than alcoholic controls. For the alcoholic controls, increasing the number of study trials had little additional effect on their exclusion performance, but it significantly enhanced their inclusion performance. Taken together, these findings suggest that for control subjects, word completion performance is likely mediated by a combination of fluency and recollection, while for amnesic patients, performance is almost exclusively based on the fluency with which an item comes to mind.

Unconscious influences revealed. Attention, awareness, and control.

Recent findings of dissociations between direct and indirect tests of memory and perception have renewed enthusiasm for the study of unconscious processing. The authors argue that such findings are heir to the same problems of interpretation as are earlier evidence of unconscious influences--namely, one cannot eliminate the possibility that conscious processes contaminated the measure of unconscious processes. To solve this problem, the authors define unconscious influences in terms of lack of conscious control and then describe a process dissociation procedure that yields separate quantitative estimates of the concurrent contributions of unconscious and consciously controlled processing to task performance. This technique allows one to go beyond demonstrating the existence of unconscious processes to examine factors that determine their magnitude.

Reinstating study context produces unconscious influences of memory.

Having read a word does more to benefit its later perceptual identification when many, rather than few, of the words in the test list have been previously read. Some have suggested that this proportion overlap effect is produced by an intentional use of recognition memory or recall in the perceptual identification task. Contrary to this account, we found that words that are easily recognized (words generated from an anagram at study) do not gain more from increasing overlap than do words that are poorly recognized (words read at study). These findings are problematic for claims that word perception relies on a module, such as a logogen system, that is separate from the rest of memory.

Direct versus indirect tests of memory for source: judgments of modality.

We studied the relation between performance on direct versus indirect tests of memory for modality. Subjects read or heard words in a mixed list and then were tested by visual perceptual identification (the indirect test) and direct report of items as read, heard, or new. There was a dependent relation between perceptual identification performance and modality judgments, in accord with the hypothesis that subjects base their judgments of modality on relative perceptual fluency. In Experiment 2, we attempted to change the degree of dependence by providing subjects with an alternative basis for modality judgments. Subjects given a mnemonic to encode modality exhibited less dependence between perceptual identification performance and modality judgments than did subjects who encoded modality incidentally. The relation between direct and indirect tests of memory for source characteristics depends on the basis used for each.