Attention and perceptual priming in the perceptual identification task.

Prior research indicates that manipulations of attention during encoding sometimes affect perceptual implicit memory. Two hypotheses were investigated. One proposes that manipulations of attention affect perceptual priming only to the extent that they disrupt stimulus identification. The other attributes reduced priming to the disruptive effects of distractor selection. The role of attention was investigated with a variant of the Stroop task in which participants either read words, identified their color, or did both. Identifying the color reduced priming even when the word was also overtly identified. This result held regardless of whether color and word were presented as a single object (Experiments 1 and 2) or as separate objects (Experiment 4). When participants read and identified a color, the overt order of the responses did not matter; both conditions reduced priming relative to reading alone (Experiment 3). The results provide evidence against the stimulus-identification account but are consistent with the distractor-selection hypothesis. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Conceptual implicit memory performance in Alzheimer's disease.

Alzheimer's disease (AD) patients often exhibit deficits on conceptual implicit memory tests such as category exemplar generation and word association. However, these tests rely on word production abilities, which are known to be disrupted by AD. The current study assessed conceptual implicit memory performance in AD patients and elderly control participants using a conceptual priming task that did not require word production (i.e., semantic decision). Memory performance was also examined using a category exemplar generation test (i.e., a conceptual priming task that required word production) and a recognition memory test. AD patients exhibited deficits on the semantic decision task, the category exemplar generation task, and the recognition memory task. The results indicate that the conceptual memory deficits observed in AD patients cannot be attributed completely to word production difficulties. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of cross-modal and intramodal division of attention on perceptual implicit memory.

Extant results motivate 3 hypotheses on the role of attention in perceptual implicit memory. The first proposes that only intramodal manipulations of attention reduce perceptual priming. The second attributes reduced priming to the effects of distractor selection operating in a central bottleneck process. The third proposes that manipulations of attention only affect priming via disrupted stimulus identification. In Experiment 1, a standard cross-modal manipulation did not disrupt priming in perceptual identification. However, when study words and distractors were presented synchronously, cross-modal and intramodal distraction reduced priming. Increasing response frequency in the distractor task produced effects of attention regardless of target-distractor synchrony. These effects generalized to a different category of distractors arguing against domain-specific interference. The results support the distractor-selection hypothesis. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On the relationship between recognition familiarity and perceptual fluency: evidence for distinct mnemonic processes

Fluent reprocessing of perceptual aspects of recently experienced stimuli is thought to support repetition priming effects on implicit perceptual memory tests. Although behavioral and neuropsychological dissociations demonstrate that separable mnemonic processes and neural substrates mediate implicit and explicit test performance, dual-process theories of memory posit that explicit recognition memory judgments may be based on familiarity derived from the same perceptual fluency that yields perceptual priming. Here we consider the relationship between familiarity-based recognition memory and implicit perceptual memory. A select review of the literature demonstrates that the fluency supporting implicit perceptual memory is functionally and anatomically distinct from that supporting recognition memory. In contrast to perceptual fluency, recognition familiarity is more sensitive to conceptual than to perceptual processing, and does not depend on modality-specific sensory cortices. Alternative possible relationships between familiarity in explicit memory and fluency in implicit memory are discussed.     

Conceptual priming in perceptual identification for patients with Alzheimer's disease and a patient with right occipital lobectomy.

Two experiments examined explicit recognition memory and perceptual and conceptual contributions to implicit perceptual-identification repetition priming for patients with Alzheimer's disease (AD) and Patient M.S. with right-occipital lobectomy. Participants read words (perceptual encoding) and generated words (conceptual encoding) from a definition and letter cue (e.g., "a vehicle for moving the injured—a"). AD patients demonstrated impaired explicit and intact implicit memory for both perceptually and conceptually encoded words. M.S. demonstrated the opposite pattern: intact explicit and impaired implicit memory in both encoding conditions. The double dissociation between AD and M.S. on implicit and explicit memory tasks is discussed in terms of a putative visual memory mechanism in the right-occipital cortex that interacts with lexical mechanisms to yield perceptual-identification priming after perceptual and conceptual encoding. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Repetition priming of words, pseudowords, and nonwords.

In 5 experiments, the authors assessed repetition priming for words, pseudowords, and nonwords using a task that combines an implicit perceptual fluency measure and a recognition memory assessment for each list item. Words and pseudowords generated a consistently strong repetition effect even when there was a failure to recognize the stimulus. In 2 of the experiments, the repetition effect for nonwords was reliably above chance even when there was a failure to recognize the stimulus. The authors propose a parallel distributed processing (PDP) model based on the work of J. McClelland and D. Rumelhart (1985) as a way to understand the mechanisms potentially responsible for the pattern of findings. Although the error-driven nature of learning in the model results in a poor fit to the nonword priming data, this is not endemic to all PDP models. Using a model based on Hebbian learning, the authors instantiate a property that they believe is characteristic of implicit memory-that learning is primarily based on the strengthening of connections between units that become active during the processing of a stimulus. This model provides a far more satisfactory account of the data than does the error-driven model. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A dissociation between perceptual explicit and implicit memory processes

Patient M.S., who underwent right-occipital lobe resection to treat intractable epilepsy, has intact recall and recognition memory for words, but impaired repetition priming in word identification and visual stem-completion tasks. This mirror dissociation to amnesia suggests that explicit recognition and visuoperceptual repetition priming are mediated by distinct neural systems. In prior studies, however, M.S.' recognition memory was tested only with tasks that drew upon his intact verbal knowledge. The present study examined M.S.' recognition memory for nonverbal perceptual information, namely, the modality and font of word presentation and line patterns. M.S.' recognition memory was intact, providing further evidence that perceptual explicit and implicit memory processes are subserved by functionally and neurally independent memory systems.     

Dissociative effect of massed repetition on implicit and explicit measures of memory.

Ss saw or heard words presented once, or repeated 4 or 16 times in massed fashion, and then received an implicit or explicit memory test. Massed repetition did not increase priming on word fragment completion beyond that obtained from a single presentation but did enhance performance on various explicit tests (free recall, recognition, question cued recall, and word fragment cued recall) and an implicit general knowledge test. Modality of presentation affected implicit and explicit word fragment cued tests but did not affect performance on any of the other tests. Levels of processing affected performance on implicit and explicit question cued tests. These results are consistent with a transfer appropriate processing account of dissociations among memory measures and imply that massed repetition promotes conceptual processing but does not entail a repetition of perceptual-based processes responsible for priming on word fragment completion. (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.     

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)     

Repetition priming of words and pseudowords in divided attention and in amnesia.

Repetition priming of novel stimuli (pseudowords) and stimuli with preexisting representations (words) was compared in 2 experiments. In one, 19 normal male Ss performed a lexical decision task with either focused or divided attention. In another, lexical decision performance was compared between 8 male Korsakoff patients and 8 alcoholic control Ss. In control conditions, repetition sped responses to both stimulus types. Experimental conditions that minimized the contribution of episodic memory to task performance eliminated reaction time (RT) priming for pseudowords but not for words. However, in these same conditions, repetition increased the likelihood that pseudowords would be incorrectly classified. These results indicate that preserved repetition priming effects in amnesia do not solely reflect activation of representations in semantic memory. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Event-related potentials differentiate the effects of aging on word and nonword repetition in explicit and implicit memory tasks.

Explicit memory declines with age while implicit memory remains largely intact. These experiments extended behavioral findings by recording event-related potentials (ERPs) in young and elderly adults during repetition priming and recognition memory paradigms. Words and pronounceable nonwords repeated after 1 of 3 delays. Stimuli were categorized as either word-nonword or old-new. Repeated items elicited more positive-going potentials in both tasks. Hemispheric asymmetries for word and nonword processing were observed during lexical decision: Repetition effects were larger over the left hemisphere for words and over the right hemisphere for nonwords. For the young, ERP repetition effects were larger during recognition memory. For old adults, conversely, repetition produced more positive-going waveforms during lexical decision. The elderly had ERP and behavioral deficits at long recognition delays. ERP repetition effects in the elderly, like behavioral performance, were preserved in an implicit task but impaired in an explicit memory task. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Levels of processing and selective attention effects on encoding in memory

The purpose of the present study was to investigate the effects of selective attention and levels of processing (LOPs) at study on long-term repetition priming vis-a-vis their effects on explicit recognition. In a series of three experiments we found parallel effects of LOP and attention on long-term repetition priming and recognition performance when the manipulation of these factors at encoding was blocked. When a mixed study condition was used, both factors affected explicit recognition, while their effect on repetition priming was determined by the nature of the test. Shallow processing at test did not benefit from long-term repetition, regardless of whether the words had been studied deeply or shallowly. Selective attention affected long-term repetition priming in a semantic, but not in a lexical decision (LD), test. Regardless of study condition, retention lag affected long-term repetition priming only in the semantic test. These results suggest that if the experimental conditions allow scrupulous selection of attended and unattended information or narrow tuning to a shallow, pre-lexical LOP, implicit access to unattended or shallowly studied items is significantly reduced, as is explicit recognition. We suggest a conceptual framework for understanding the effects of LOP, attention, and retention interval on performance of explicit and implicit tests of memory.     

Eliminating inhibition of return by changing salient nonspatial attributes in a complex environment.

Inhibition of return (IOR) occurs when a target is preceded by an irrelevant stimulus (cue) at the same location: Target detection is slowed, relative to uncued locations. In the present study, we used relatively complex displays to examine the effect of repetition of nonspatial attributes. For both color and shape, attribute repetition produced a robust inhibitory effect that followed a time course similar to that for location-based IOR. However, the effect only occurred when the target shared both the feature (i.e., color or shape) and location with the cue; this constraint implicates a primary role for location. The data are consistent with the idea that the system integrates consecutive stimuli into a single object file when attributes repeat, hindering detection of the second stimulus. The results are also consistent with an interpretation of IOR as a form of habituation, with greater habituation occurring with increasing featural overlap of a repeated stimulus. Critically, both of these interpretations bring the IOR effect within more general approaches to attention and perception, rather than requiring a specialized process with a limited function. In this view, there is no process specifically designed to inhibit return, suggesting that IOR may be the wrong framing of inhibitory repetition effects. Instead, we suggest that repetition of stimulus properties can interfere with the ability to focus attention on the aspects of a complex display that are needed to detect the occurrence of the target stimulus; this is a failure of activation, not an inhibition of processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Recognition memory: neuronal substrates of the judgement of prior occurrence

Recognition memory relies on two processes: (i) identification and (ii) judgement concerning prior occurrence. A system centred on perirhinal cortex appears to be responsible for judgement of prior occurrence based on discrimination of the familiarity of stimuli or their recency of occurrence; in contrast, a hippocampal system probably supplies information concerning the episodic, contextual aspects of recognition memory. This review chiefly concerns the perirhinal system and, in particular, neurones that signal the prior occurrence of stimuli by a decrease in response. Details concerning such decremental responses are given and it is argued that such responses in perirhinal cortex are adequate for and central to discrimination of stimulus familiarity and recency in a wide range of situations. Information is given of similar types of neuronal responses in anatomically related brain regions and what may be deduced about the operation of the recognition memory system. The possibility is discussed that the neuronal responses that signal information concerning the recent occurrence of stimuli may contribute to repetition priming as well as recognition memory. Other described changes in the activity of individual neurones such as response enhancements, or sustained (delay) activity may allow solution of specialised forms of recognition memory tasks where relatively short-term working memory is adequate. Implications of the multi-faceted nature of recognition memory for the interpretation of results are emphasised. Unsolved problems and avenues for future experimentation, including determining the nature of possible underlying synaptic plastic changes, are discussed.     

What's the use of being happy? Mood states, useful objects, and repetition priming effects.

Two experiments involving 99 undergraduate participants sought to examine the influence of mood states on encoding speed within lexical decision and pronunciation tasks. Mood states were measured naturalistically in Experiment 1 and manipulated in Experiment 2. Stimuli consisted of nouns representing useful (e.g., food) and nonuseful (e.g., lint) objects. Mood states had no implications for initial encoding speed. However, when the same words were presented a 2nd time (i.e., repeated), happy individuals displayed a tendency to encode useful words faster than nonuseful ones. Thus, mood states influenced repetition priming on the basis of stimulus valence. The authors propose that happiness sensitizes individuals to useful or rewarding objects, which in turn creates a stronger memory trace for such stimuli in the future. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Affective priming of naming responses does not depend on stimulus repetition.

The finding that naming responses can be affectively primed suggests (a) that stimulus evaluation does not depend on participants having an explicit evaluative processing goal, and (b) that the perception of an affectively polarized stimulus can result in the preactivation of memory representations of affectively related stimuli. However, in all published studies that demonstrated significant affective priming of naming responses, both the primes and the targets were repeatedly presented. Hence, one cannot rule out the possibility that stimulus repetition is a prerequisite for obtaining affective priming of naming responses. We examined (a) whether affective priming of naming responses can be obtained in the absence of stimulus repetition, and (b) whether affective priming in the naming task is affected by the number of stimulus presentations. Results show that affective priming of naming responses does not depend on stimulus repetition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Does implicit memory extend to legal and illegal nonwords?

In 4 experiments, implicit and explicit memory for words and nonwords were compared. In Exps 1–2 memory for words and legal nonwords (e.g., kers) was assessed with an identification (implicit) and a recognition (explicit) memory task: Robust priming was obtained for both words and nonwords, and the priming effects dissociated from explicit memory following a levels-of-processing manipulation (Exp 1) and following a study-test modality shift (Exp 2). In Exp 3, priming for legal and illegal nonwords (e.g., xyks) was observed on an identification task, and the effects dissociated from explicit memory following a levels-of-processing manipulation. Finally, in Exp 4, significant inhibitory priming for legal nonwords was observed when a lexical-decision task was used. Results suggest that implicit memory can extend to legal and illegal nonwords. Implications for theories of implicit memory are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Correction to Berry et al. (2010).

Reports an error in "Can “pure” implicit memory be isolated? A test of a single-system model of recognition and repetition priming" by Christopher J. Berry, David R. Shanks, Selina Li, Luke Sheridan Rains and Richard N. A. Henson (Canadian Journal of Experimental Psychology/Revue canadienne de psychologie expérimentale, 2010[Dec], Vol 64[4], 241-255). In the article there was an error in Equation B2 in Appendix B. (The following abstract of the original article appeared in record 2010-26226-002.) Implicit memory is widely regarded as an unconscious form of memory. However, evidence for what is arguably a defining characteristic of implicit memory—that its contents are not accessible to awareness—has remained elusive. Such a finding of “pure” implicit memory would constitute evidence against a single-system model of recognition and priming that predicts that priming will not occur in the (true) absence of recognition. In three experiments, using a rapid serial visual presentation procedure at encoding, we tested this prediction by attempting to replicate some previous studies that claimed to obtain pure implicit memory. We found no evidence of priming in the absence of recognition; instead, priming and recognition were associated across experiments: when priming was absent, recognition was also absent (Experiments 1 and 2), and when priming was reliably greater than chance, recognition was similarly greater than chance (Experiment 3). The results are consistent with the prediction of a single-system model, which was fit to the data from all the experiments. The results are also consistent with the notion that the memory driving priming is accessible to awareness. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Bias effects in implicit memory tasks.

A major focus of recent research in memory has been performance on implicit tasks. The phenomenon of most interest has been repetition priming, the effect that prior exposure to a stimulus has on later perception of the stimulus or on a later decision about the stimulus. Picture naming, word identification, and word production in stem- and fragment-completion tasks all show repetition priming effects. The separation of implicit from explicit memory systems provides 1 account of this data, but a different theoretical view is proposed here: Repetition-priming effects come about because the processes that perform a task are biased by prior exposure to a stimulus. The processing of the prior stimulus leaves behind byproducts, temporary modifications of the processes, which influence later processing. The aim of this article is to demonstrate the potential of this view for developing new theories and for prompting new empirical questions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)