Visual memory for novel shapes: Implicit coding without attention.

Implicit memory for novel shapes was explored with a negative priming paradigm. The results show that representations of shapes, formed in a single trial and without attention, can last without decrement across 200 intervening trials and with temporal delays of up to a month. No explicit memory of the shapes was available, either immediately or after a delay. There were consistent individual differences in the amount of negative priming shown, and some participants showed only facilitation. There was a trend toward increased facilitation across time, as if the memory of the shape survived longer than an "action tag" attached to it, which specified whether it should be attended or ignored. The results demonstrate a surprising combination of plasticity and permanence in the visual system and suggest that the roles of both attention and repetition may be to ensure voluntary retrievability rather than to form a lasting memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Implicit memory: History and current status.

Memory for a recent event can be expressed explicitly, as conscious recollection, or implicitly, as a facilitation of test performance without conscious recollection. A growing number of recent studies have been concerned with implicit memory and its relation to explicit memory. This article presents an historical survey of observations concerning implicit memory, reviews the findings of contemporary experimental research, and delineates the strengths and weaknesses of alternative theoretical accounts of implicit memory. It is argued that dissociations between implicit and explicit memory have been documented across numerous tasks and subject populations, represent an important challenge for research and theory, and should be viewed in the context of other dissociations between implicit and explicit expressions of knowledge that have been documented in recent cognitive and neuropsychological research. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Implicit memory and test awareness.

In three experiments we examined whether normal subjects can perform an implicit test without becoming aware that the test items were previously encountered in the study phase of the experiment. Experiment 1 assessed single word priming with the stem completion task, and subjects who reported awareness/unawareness that the test items were previously encoded in the study task showed equivalent priming. Experiments 2a–c and 3 assessed associative priming with the stem completion task, and in this case, only subjects who were aware that the test items were previously encountered showed associative priming effects. These findings suggest that single word priming and associative priming reflect different memory processes because the former and not the latter effect can be observed in unaware subjects. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Implicit memory in Alzheimer's disease: A meta-analysis.

Meta-analysis was performed on 33 articles (36 experiments involving 564 Alzheimer's disease [AD] patients and 592 controls). Overall, AD patients were significantly impaired on implicit memory tests, r?=?.163 (a difference of .329 SDs from normal performance). They were impaired on nonverbal tests (e.g., fragmented pictures), word stem completion, classical conceptual tests (e.g, free association), and on word-based perceptual tests with long delays. However, they performed normally on word-based perceptual tests (e.g., perceptual identification of words) with short study test delays. They also performed normally on word stem completion if they were older than 75, possibly because their age-matched controls were also impaired. These results are neither qualified by study list length nor patient mental status. None of the theories in the field is compatible with the results. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Implicit memory research in 1996: Introductory remarks.

This special issue of the Canadian Journal of Experimental Psychology is titled "Implicit Memory Research in 1996." Implicit memory now occupies centre stage in the study of memory, and as such, the editor of the journal saw the need for a special issue. In this special issue, several articles investigate priming on perceptually-cued tests and contribute to our understanding of the nature of implicit retrieval on perceptually-cued tests. The study of priming has been dominated by the use of verbal tasks, like the tasks used in the previous articles. However, priming can be revealed in many ways, and it is important that researchers explore the nature of priming in a variety of experimental situations so as to broaden our knowledge and understanding of implicit memory. Several articles in this special issue do this. Each article stands on it own and makes a novel and important contribution. At the same time, the articles share similarities which also helped to determine the order of presentation of the articles in the issue. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perceptual effects on remembering: Recollective processes in picture recognition memory.

In 3 experiments, the effects of perceptual manipulations on recollective experience were tested. In Experiment 1, a picture-superiority effect was obtained for overall recognition and Remember judgments in a picture recognition task. In Experiment 2, size changes of pictorial stimuli across study and test reduced recognition memory and Remember judgments. In Experiment 3, deleterious effects of changes in left–right orientation of pictorial stimuli across study and test were obtained for Remember judgments. An alternate framework that emphasizes a distinctiveness–fluency processing distinction is proposed to account for these findings because they cannot easily be accommodated within the existing account of differences in conceptual and perceptual processing for the 2 categories of recollective experience: Remembering and Knowing, respectively (J. M. Gardiner, 1988; S. Rajaram, 1993). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Collective memory: collaborative and individual processes in remembering

Two experiments compared collaborative and individual recall. In Experiment 1, participants encoded pictures and words with a deep or shallow processing task, then recalled them twice either individually or collaboratively. Collaborative groups recalled more than individuals, but less than nominal groups (pooled individuals), thus exhibiting collaborative inhibition. However, group recall appeared to be more stable over time than individual recall. Groups and individuals both showed a picture-superiority effect, a level-of-processing effect, and hypermnesia. In Experiment 2, participants recalled the story "War of the Ghosts" (from F. C. Bartlett, 1932), and again collaborative groups recalled more than individuals, but less than nominal groups. Both the individual and collaborative recalls were highly organized. There was evidence that the collaborative groups tended to rely on the best individual to a greater extent in story than in list recall. Possible social and cognitive mechanisms are considered.     

Implicit, long-term spatial contextual memory.

Learning and memory of novel spatial configurations aids behaviors such as visual search through an implicit process called contextual cuing (M. M. Chun & Y. Jiang, 1998). The present study provides rigorous tests of the implicit nature of contextual cuing. Experiment 1 used a recognition test that closely matched the learning task, confirming that memory traces of predictive spatial context were not accessible to conscious retrieval. Experiment 2 gave explicit instructions to encode visual context during learning, but learning was not improved and conscious memory remained undetectable. Experiment 3 illustrates that memory traces for spatial context may persist for at least 1 week, suggesting a long-term component of contextual cuing. These experiments indicate that the learning and memory of spatial context in the contextual cuing task are indeed implicit. The results have implications for understanding the neural substrate of spatial contextual learning, which may depend on an intact medial temporal lobe system that includes the hippocampus (M. M. Chun & E. A. Phelps, 1999). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A stability bias in human memory: Overestimating remembering and underestimating learning.

The dynamics of human memory are complex and often unintuitive, but certain features—such as the fact that studying results in learning—seem like common knowledge. In 12 experiments, however, participants who were told they would be allowed to study a list of word pairs between 1 and 4 times and then take a cued-recall test predicted little or no learning across trials, notwithstanding their large increases in actual learning. When queried directly, the participants espoused the belief that studying results in learning, but they showed little evidence of that belief in the actual task. These findings, when combined with A. Koriat, R. A. Bjork, L. Sheffer, and S. K. Bar’s (2004) research on judgments of forgetting, suggest a stability bias in human memory—that is, a tendency to assume that the accessibility of one’s memories will remain relatively stable over time rather than benefiting from future learning or suffering from future forgetting. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Implicit and explicit memory for visual patterns.

The article reports an investigation of implicit and explicit memory for novel, visual patterns. Implicit memory was assessed by a speeded perception task, and explicit memory by a four-alternative, forced-choice recognition task. Tests were given either immediately after testing or 7 days later. The results suggest that a single exposure of a novel, nonverbal stimulus is sufficient to establish a representation in memory that is capable of supporting long-lived perceptual priming. In contrast, recognition memory showed significant loss over the same delay. Performance measures in the two tasks showed stochastic independence on the first trial after a single exposure to each pattern. Finally, a specific occurrence of a previously studied item could be retrieved from explicit memory but did not affect the accuracy of perception in the implicit memory test. The results extend the domain of experimental dissociations between explicit and implicit memory to include novel, nonverbal stimuli. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Implicit and explicit memory bias in anxiety.

Previous investigations of recall and recognition for threatening information in clinically anxious subjects have yielded equivocal results. The present study contrasts implicit (word completion) with explicit (cued recall) memory and shows that indices of bias for emotional material derived from the two types of memory are independent of one another. The explicit measure was correlated with trait anxiety scores, but did not clearly distinguish between subjects with clinical anxiety states and normal control subjects. On the implicit memory measure, clinically anxious subjects produced more threat word completions, but only from a set to which they had recently been exposed. These results are taken as evidence that internal representations of threat words are more readily or more persistently activated in anxiety states, although they are not necessarily better elaborated. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Implicit memory for music in Alzheimer's disease.

Short, unfamiliar melodies were presented to young and older adults and to Alzheimer's disease (AD) patients in an implicit and an explicit memory task. The explicit task was yes–no recognition, and the implicit task was pleasantness ratings, in which memory was shown by higher ratings for old versus new melodies (the mere exposure effect). Young adults showed retention of the melodies in both tasks. Older adults showed little explicit memory but did show the mere exposure effect. The AD patients showed neither. The authors considered and rejected several artifactual reasons for this null effect in the context of the many studies that have shown implicit memory among AD patients. As the previous studies have almost always used the visual modality for presentation, they speculate that auditory presentation, especially of nonverbal material, may be compromised in AD because of neural degeneration in auditory areas in the temporal lobes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Implicit memory for nonverbal associations

A color-naming priming task was used to examine implicit memory for new nonverbal associations. Implicit memory was observed for associations between words and colors and between abstract shapes and colors. The authors also asked whether nonverbal association priming might occur more readily than verbal association priming. Colored compound nonwords were used as stimuli, and participants were asked to attend either to the 2 syllables of the compound nonword or to the compound nonword and the color in which it was printed. The authors found that the association formed depended on which attributes of the stimuli were attended to and were not more readily formed for nonverbal material. The results demonstrate that tasks that encourage unitization between the elements to be associated facilitate associative priming.     

Auditory priming: Implicit and explicit memory for words and voices.

Five experiments explore priming effects on auditory identification and completion tasks as a function of semantic and nonsemantic encoding tasks and whether speaker's voice is same or different at study and test. Auditory priming was either unaffected by the study task manipulation (Exps 2, 4, and 5) or was less affected than was explicit memory (Exps 1 and 3). Study-to-test changes of speaker's voice had significant effects on priming when white noise masked target items on the identification test (Exps 1 and 2) or the stem-completion test (Exp 5). However, significant voice change effects were observed on priming of completion performance when stems were spoken clearly (Exps 3 and 4). Results are consistent with the idea that a presemantic auditory perceptual representation system plays an important role in the observed priming. Alternative explanations of the presence or absence of voice change effects under different task conditions are considered. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Implicit memory during balanced anaesthesia. Lack of evidence

The effect of the number of presentations on implicit memory for words was studied in anaesthetised patients. During standardised, balanced anaesthesia, 81 surgical patients were presented with less common specimens of familiar word categories. For each of three word categories the number of word presentations varied between the patients (0 (control), 5, or 30 presentations). Postoperatively, repetition priming was tested by asking patients to generate exemplars for each of the word categories. No implicit memory for the words presented during anaesthesia was found and consequently no effect of number of word presentations could be demonstrated. It is suggested that this finding, which contradicts previous results, may be caused by the relatively low familiarity of the words used.     

The development of memory efficiency and value-directed remembering across the life span: A cross-sectional study of memory and selectivity.

Although attentional control and memory change considerably across the life span, no research has examined how the ability to strategically remember important information (i.e., value-directed remembering) changes from childhood to old age. The present study examined this in different age groups across the life span (N = 320, 5–96 years old). A selectivity task was used in which participants were asked to study and recall items worth different point values in order to maximize their point score. This procedure allowed for measures of memory quantity/capacity (number of words recalled) and memory efficiency/selectivity (the recall of high-value items relative to low-value items). Age-related differences were found for memory capacity, as young adults recalled more words than the other groups. However, in terms of selectivity, younger and older adults were more selective than adolescents and children. The dissociation between these measures across the life span illustrates important age-related differences in terms of memory capacity and the ability to selectively remember high-value information. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

The effects of environmental context on recognition memory and claims of remembering.

Recognition memory for words was tested in same or different contexts using the remember/know response procedure. Context was manipulated by presenting words in different screen colors and locations and by presenting words against real-world photographs. Overall hit and false-alarm rates were higher for tests presented in an old context compared to a new context. This concordant effect was seen in both remember responses and estimates of familiarity. Similar results were found for rearranged pairings of old study contexts and targets, for study contexts that were unique or were repeated with different words, and for new picture contexts that were physically similar to old contexts. Similar results were also found when subjects focused attention on the study words, but a different pattern of results was obtained when subjects explicitly associated the study words with their picture context. The results show that subjective feelings of recollection play a role in the effects of environmental context but are likely based more on a sense of familiarity that is evoked by the context than on explicit associations between targets and their study context. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Mundane remembering.

Reviews the book, Remembering Reconsidered: Ecological and Traditional Approaches to the Study of Memory by Ulric Neisser and Eugene Winograd (see record 1988-98127-000). This volume is the second in a series known as The Emory Symposia in Cognition. The first volume addressed the question of "ecological and intellectual factors in categorization" and this second collection of papers pursues the ecological theme into the challenging realm of memory. As often happens with published symposia, the collection of chapters is greatly enlivened by the integrative commentary of thoughtful critics. In this volume this function is particularly well served with separate contributions by Neisser, Winograd, McCauley, Fivush, and by Rubin. My only regret is that none of them managed to bring order into the chaotic use of the term functional as it appears in various parts of the symposium. These commentaries add to the primary contributions in a way that results in a volume that is thematically more integrated than many such symposium collections. None of the contributions digs deeply into the real issues underlying the relationship between naturalistic and laboratory studies, but most of them demonstrate by way of example that the two approaches can serve complementary roles and a common goal. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Implicit memory: Effects of network size and interconnectivity on cued recall.

Previous findings have indicated that the recall of a recently studied word is affected by how many associates it has in long-term memory (set size). The purpose of these experiments was to determine whether recall is also affected by the connectivity of these associates. Studied words were preselected to represent combinations of set size and connectivity and, in different experiments, recall was cued with extralist or intralist cues and with cues sharing few or many associates with the studied words. Effects of study time, encoding context, and levels of processing were also investigated. The results indicated that recall was more likely for words with smaller associative sets and for words with more interconnected sets of associates. These findings demonstrate that the recall of a recently presented word in the presence of a retrieval cue is affected by both the size and organization of its implicitly activated associative structure. (PsycINFO Database Record (c) 2010 APA, all rights reserved)