Implicit Memory For New Associations Research Articles

Implicit memory for novel associations between pictures: effects of stimulus unitization and aging.

Studies of implicit memory for novel associations have focused primarily on verbal materials and have highlighted the contribution of conceptually unitized representations to such priming. Using pictorial stimuli in a perceptual identification task, we examined whether new association priming can occur at a purely perceptual level. By manipulating the spatial contiguity of stimuli, we also evaluated whether such priming requires the creation of perceptually unitized representations. Finally, we examined the status of such priming in aging. In Experiment 1, we found that spatial contiguity of stimuli is not necessary for novel pictorial association priming to emerge, although such contiguity does enhance the magnitude of associative priming. In Experiment 2, we found that new association priming is age invariant, regardless of spatial contiguity. In Experiment 3, we provide additional evidence that pictorial association priming is perceptually based. These findings expand the scope and delineate the conditions of novel association priming and inform theories about the nature of implicit memory for new associations.

Involvement of the medial temporal lobe in priming for new associations

This study was addressed to the question of whether the medial temporal lobe (MTL) plays a critical role in implicit memory for new associations. Priming for new associations was examined in two different tasks in 18 patients with focal lesions all involving the MTL. In Experiment 1, following a study phase for pairs of unrelated words, subjects performed a perceptual identification task on old, recombined, and new pairs of words presented at brief exposure durations. In contrast to control subjects, and despite a normal level of item priming, the patients failed to show superior identification of the old pairs relative to the recombined pairs, the measure of associative priming. In Experiment 2, subjects engaged in speeded naming of the print color for previously studied words presented in the original color or in a different old color, and for unstudied words. Again, in contrast to control subjects and despite a normal level of item facilitation on color naming reaction time (RT), the patients failed to show priming for recently experienced new associations between words and colors. Explicit recognition memory by the patients was abnormal in both experiments. This study records an absence of priming for new associations, in two different tasks in which the nature of the stimuli was considerably different, in a large group of patients with lesions in the MTL. Although some previous research has reported significant associative priming in other tasks for patients with MTL lesions, the present results suggest that this region is critical for forming new associations of the types assessed here.

Preservation of Implicit Memory for New Associations in Global Amnesia

This study examined whether amnesic patients have preserved implicit memory for new associations between unrelated words, as measured by repetition priming, despite impaired explicit memory for such new associations Prior studies provide conflicting and ambiguous results Amnesic and control participants read aloud visually presented, unrelated word pairs and then attempted to identify old, recombined, and new word pairs shown at threshold durations Amnesic and control groups showed equivalent priming for new associations by identifying old pairs better than recombined pairs Amnesic patients were impaired on a matched explicit test of memory for new associations The preserved priming in amnesia indicates that implicit memory for new associations need not be supported by the mnemonic processes and brain structures that mediate explicit memory for new associations.

Sources of priming in text rereading: intact implicit memory for new associations in older adults and in patients with Alzheimer's disease.

The contributions of text meaning, new between-word associations, and single-word repetition to priming in text rereading in younger and older adults, and in patients with Alzheimer's disease. (AD), were assessed in Experiment 1. Explicit recognition memory for text was also assessed. Equivalent single-word and between-word priming was observed for all groups, even though patients with AD showed impaired explicit memory for individual words in the text. The contribution of generalized reading task skill to priming in meaningless text rereading in younger adults was assessed in Experiment 2. Generalized reading task skill was also found to contribute to priming. These results reveal 3 mechanisms of priming: new between-word associations for meaningful and meaningless text, individual word repetition for meaningless text, and general task or skill factors for meaningless text. All priming mechanisms appear to be intact in older adults and in patients with AD.

Sources of priming in text rereading: Intact implicit memory for new associations in older adults and in patients with Alzheimer's disease.

Sources of priming in text rereading: Intact implicit memory for new associations in older adults and in patients with Alzheimer's disease.

Implicit memory for new associations: The pictorial influence

A series of experiments was conducted in order to show that implicit memory for new associations is not always dependent on semantic integrative processing during study. The material used in these experiments differed from traditional studies that employed pairs of unrelated words. Instead, targets (words in Exps. 1 and 2 and pictures in Exps. 3 and 4) were encoded in the context of an unrelated picture. The implicit tests used were word-stem completion (Exps. 1, 2, and 3) and picture-fragment identification (Exp. 4). The explicit test was word-stem cued recall (Exps. 1, 2, and 3) and picture-fragment cued recall (Exp 4). For implicit tests, context effects were not obtained using words as targets with a non-integrative semantic-elaboration encoding task (Exp. 1). When an integrative semantic-elaboration encoding task was used, a standard context effect emerged (Exp. 2) for implicit memory. Importantly, with pictures as targets, context effects appeared without integrative semantic encoding (Exps. 3 and 4). However, context effects were obtained for all conditions of cued recall. Results are discussed with regard to the concept of unitization.

Modality specificity of implicit memory for new associations.

In previous research we demonstrated that newly acquired associations between unrelated word pairs influence the magnitude of priming effects on word-completion tests. This phenomenon of implicit memory for new associations is observed only following semantic study elaboration. The present experiments reveal that implicit memory for new associations, though elaboration dependent, is also modality specific: Associative effects on a visual word-completion test were consistently reduced by study-test modality shifts. In contrast, explicit memory for new associations, as indexed by cued-recall performance, was uninfluenced by modality shifts. The modality effect on completion performance was eliminated when subjects were given brief visual preexposures to, or were required to construct visual images of, word pairs presented in auditory study conditions. The results pose a theoretical puzzle insofar as they indicate that within the domain of implicit memory, access to the products of elaborative processing depends on modality-specific, sensory-perceptual processing.

Modality specificity of implicit memory for new associations.

Modality specificity of implicit memory for new associations.

Selective effects of interference on implicit and explicit memory for new associations.

On standard memory tests, such as recall and recognition, subjects are required to recollect where, when, and under what specific circumstances a target item was acquired; on priming tests, such as word completion and word identification, no reference is made to the specific circumstances accompanying an item's acquisition. We have used the labels explicit and implicit to describe the forms of memory that are indexed by these two types of tests. Recent research has shown performance dissociations between explicit and implicit memory for newly acquired associations. To learn more about the nature of these dissociations, the present study examined the etfects of an AB, AC interference manipulation on explicit and implicit memory for pairs of normatively unrelated words. Interference affected explicit memory, as indexed by performance on cued recall, pair matching, and modified modified free-recall tests, but did not affect implicit memory, as indexed by performance on a word-completion test. This pattern of results complements previous findings of performance dissociations between explicit and implicit memory for new associations. Standard memory tests, such as free recall, cued recall, and recognition, explicitly require subjects to retrieve items that were studied in a specific learning episode. In contrast, priming tests, such as word completion, word identification, and lexical decision, do not require subjects to retrieve items from a specific episode. In view of this difference in requirements, it has been suggested that the retrieval of a recently studied item on a standard memory test, and the retrieval of the same item on a priming test, reflect distinct forms of memory. For descriptive purposes, we have labeled these explicit and implicit memory, respectively (cf. Graf & Schacter, 1985). Explicit memory is revealed by intentional recollection from a specific previous episode, whereas implicit memory is revealed when performance on a task is facilitated without deliberate recollection from a specific learning episode.

Implicit and explicit memory for new associations in normal and amnesic subjects.

Two experiments examined whether repetition priming effects on a word completion task are influenced by new associations between unrelated word pairs that were established during a single study trial. On the word completion task, subjects were presented with the initial three letters of the response words from the study list pairs and they completed these fragments with the first words that came to mind. The fragments were shown either with the paired words from the study list (same context) or with other words (different context). Both experiments showed a larger priming effect in the same-context condition than in the different-context condition, but only with a study task that required elaborative processing of the word pairs. This effect was observed with college students and amnesic patients, suggesting that word completion performance is mediated by implicit memory for new associations that is independent of explicit recollection.