Implicit Spatial Contextual Learning in Healthy Aging.

Three experiments investigated the aging of implicit spatial and spatiotemporal context learning in 2 tasks. In contextual cuing, people learn to use repeated spatial configurations to facilitate search for a target, whereas in higher order serial learning, they learn to use subtle sequence regularities to respond more quickly and accurately to a series of events. Results reveal a dissociation; overall contextual cuing is spared in healthy aging, whereas higher order sequence learning is impaired in the same individuals. This finding suggests that these 2 forms of implicit learning rely on different neural substrates that age differently; the results are also consistent with recent evidence that fronto-striatal circuits are particularly susceptible to decline in health aging. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Spatial context learning survives interference from working memory load.

The human visual system is constantly confronted with an overwhelming amount of information, only a subset of which can be processed in complete detail. Attention and implicit learning are two important mechanisms that optimize vision. This study addressed the relationship between these two mechanisms. Specifically we asked, Is implicit learning of spatial context affected by the amount of working memory load devoted to an irrelevant task? We tested observers in visual search tasks where search displays occasionally repeated. Observers became faster when searching repeated displays than unrepeated ones, showing contextual cuing. We found that the size of contextual cuing was unaffected by whether observers learned repeated displays under unitary attention or when their attention was divided using working memory manipulations. These results held when working memory was loaded by colors, dot patterns, individual dot locations, or multiple potential targets. We conclude that spatial context learning is robust to interference from manipulations that limit the availability of attention and working memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Implicit memory for spatial context in depression and schizophrenia.

Deficits in explicit spatial memory, as well as abnormalities of the hippocampus and neighboring medial temporal structures, have been documented in schizophrenia and depression. Recent evidence relying on the contextual cueing paradigm has shown that integrity of these structures is crucial not only for explicit memory but also for implicit spatial memory. Using this paradigm, the authors show that implicit memory for spatial context is severely impaired in clinically depressed patients but reaches a normal level in schizophrenia patients, although in these patients, acquisition is slower than in controls. By contrast, implicit memory for isolated locations and colors is normal in both schizophrenia and depressed patients. These findings suggest an implicit memory impairment specific to spatial context in depression. The implications for research on the differences between schizophrenia and depression in abnormalities of the hippocampal system and for research on the neural correlates of contextual cueing are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Aging and implicit learning: Explorations in contextual cuing.

In contextual cuing, faster responses are made to repeated displays containing context–target associations than to novel displays without such covariances. We report that healthy older adults showed learning impairments in contextual cuing when compared with younger adults. The display properties in the task were altered to artificially increase younger adults' response times to match those of older adults and to produce faster responses in older participants; however, younger participants' learning remained intact, whereas older participants continued to show impairments under these conditions. These results suggest that older adults have intrinsic deficits in contextual cuing that cannot be attributed to their slower overall response speed. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Semantic contextual cuing and visual attention.

Since M. M. Chun and Y. Jiang's (1998) original study, a large body of research based on the contextual cuing paradigm has shown that the visuocognitive system is capable of capturing certain regularities in the environment in an implicit way. The present study investigated whether regularities based on the semantic category membership of the context can be learned implicitly and whether that learning depends on attention. The contextual cuing paradigm was used with lexical displays in which the semantic category of the contextual words either did or did not predict the target location. Experiments 1 and 2 revealed that implicit contextual cuing effects can be extended to semantic category regularities. Experiments 3 and 4 indicated an implicit contextual cuing effect when the predictive context appeared in an attended color but not when the predictive context appeared in an ignored color. However, when the previously ignored context suddenly became attended, it immediately facilitated performance. In contrast, when the previously attended context suddenly became ignored, no benefit was observed. Results suggest that the expression of implicit semantic knowledge depends on attention but that latent learning can nevertheless take place outside the attentional field. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Implicit memory is not immune to interference.

Does interference, a primary source of forgetting in explicit memory, also affect implicit memory? Several early and highly influential studies have suggested that implicit memory is immune to interference. In contrast, a number of subsequent investigations have reported evidence for interference. As well, amnesic patients, whose performance relies primarily on implicit memory, often show interference effects. A review of methods, materials, and findings suggests that interference occurs on implicit tests when targets and nontargets are similar and so compete as potential responses to the memory cue. Further, there is some evidence that the degree of interference on implicit tasks is affected by the number of competing items and their strength relative to the target. Interference effects in implicit memory seem to parallel those in explicit memory, and the authors consider the implications of this conclusion for theoretical concepts of memory and the brain. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Spatial exploration is required for the formation of contextual fear memory.

The acquisition of contextual fear in mice is thought to require the formation of a conjunctive representation of the conditioning chamber. This can be achieved during a minimum of 20 to 40 s of exploration immediately prior to the shock or during preexposure to the context at an earlier time. An animal receiving less time in the chamber will show reduced freezing 24 hr later, a condition termed the immediate shock deficit (ISD). In this study, the authors have attempted to uncouple the formation of a contextual representation, based on the conjunction of a defined set of cues, from the establishment of a spatial representation, which requires active exploration, by inserting a transparent plastic partition in the center of the chamber. Taking advantage of the ISD and the context preexposure effect, the authors found that animals preexposed to one side of the chamber on Day 1, but shocked on the other side on Day 2, show significantly less fear than animals exposed to and shocked on the same side. Our results indicate that spatial exploration is necessary for mice to benefit from contextual preexposure. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Long-term semantic memory versus contextual memory in unconscious number processing.

Subjects classified visible 2-digit numbers as larger or smaller than 55. Target numbers were preceded by masked 2-digit primes that were either congruent (same relation to 55) or incongruent. Experiments 1 and 2 showed prime congruency effects for stimuli never included in the set of classified visible targets, indicating subliminal priming based on long-term semantic memory. Experiments 2 and 3 went further to demonstrate paradoxical unconscious priming effects resulting from task context. For example, after repeated practice classifying 73 as larger than 55, the novel masked prime 37 paradoxically facilitated the "larger" response. In these experiments task context could induce subjects to unconsciously process only the leftmost masked prime digit, only the rightmost digit, or both independently. Across 3 experiments, subliminal priming was governed by both task context and long-term semantic memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Implicit sequence learning and contextual cueing do not compete for central cognitive resources.

Sequence learning and contextual cueing explore different forms of implicit learning, arising from practice with a structured serial task, or with a search task with informative contexts. We assess whether these two learning effects arise simultaneously when both remain implicit. Experiments 1 and 2 confirm that a cueing effect can be observed under a continuous setting and that there is no interference between contextual cueing and sequence learning. Experiments 3a and 3b tested whether an interference arises specifically when the sequence becomes explicit. Results show that the expression of contextual cueing disappeared in those conditions but that context information is still acquired, and it affects performance when the sequence is removed. The results are discussed in relation to the current debates about the automaticity of implicit learning, and about the role of attention in the acquisition and expression of contextual cueing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The nesting of search contexts within natural scenes: Evidence from contextual cuing.

In a contextual cuing paradigm, we examined how memory for the spatial structure of a natural scene guides visual search. Participants searched through arrays of objects that were embedded within depictions of real-world scenes. If a repeated search array was associated with a single scene during study, then array repetition produced significant contextual cuing. However, expression of that learning was dependent on instantiating the original scene in which the learning occurred: Contextual cuing was disrupted when the repeated array was transferred to a different scene. Such scene-specific learning was not absolute, however. Under conditions of high scene variability, repeated search array were learned independently of the scene background. These data suggest that when a consistent environmental structure is available, spatial representations supporting visual search are organized hierarchically, with memory for functional subregions of an environment nested within a representation of the larger scene. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Spatial constraints on learning in visual search: Modeling contextual cuing.

Predictive visual context facilitates visual search, a benefit termed contextual cuing (M. M. Chun & Y. Jiang, 1998). In the original task, search arrays were repeated across blocks such that the spatial configuration (context) of all of the distractors in a display predicted an embedded target location. The authors modeled existing results using a connectionist architecture and then designed new behavioral experiments to test the model's assumptions. The modeling and behavioral results indicate that learning may be restricted to the local context even when the entire configuration is predictive of target location. Local learning constrains how much guidance is produced by contextual cuing. The modeling and new data also demonstrate that local learning requires that the local context maintain its location in the overall global context. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Temporal contextual cuing of visual attention.

Previous research has shown how spatial attention is guided to a target location, but little is understood about how attention is allocated to an event in time. The authors introduce a paradigm to manipulate the sequential structure of visual events independent of responses. They asked whether this temporal context could be implicitly learned and used to guide attention to a relative point in time or location, or both, in space. Experiments show that sequentially structured event durations, event identities, and spatiotemporal event sequences can guide attention to a point in time as well as to a target event's identity and location. Cuing was found to rely heavily on the element immediately preceding the target, although cuing from earlier items also was evident. Learning was implicit in all cases. These results show that the sequential structure of the visual world plays an important role in guiding visual attention to target events. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Competitive short-term and long-term memory processes in spatial habituation.

Exposure to a spatial location leads to habituation of exploration such that, in a novelty preference test, rodents subsequently prefer exploring a novel location to the familiar location. According to Wagner's (1981) theory of memory, short-term and long-term habituation are caused by separate and sometimes opponent processes. In the present study, this dual-process account of memory was tested. Mice received a series of exposure training trials to a location before receiving a novelty preference test. The novelty preference was greater when tested after a short, rather than a long, interval. In contrast, the novelty preference was weaker when exposure training trials were separated by a short, rather than a long interval. Furthermore, it was found that long-term habituation was determined by the independent effects of the amount of exposure training and the number of exposure training trials when factors such as the intertrial interval and the cumulative intertrial interval were controlled. A final experiment demonstrated that a long-term reduction of exploration could be caused by a negative priming effect due to associations formed during exploration. These results provide evidence against a single-process account of habituation and suggest that spatial habituation is determined by both short-term, recency-based memory and long-term, incrementally strengthened memory. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Unintended influences of perception and memory: Attention, awareness, and control.

There has been a great deal of recent interest in the finding of dissociations between performance on implicit or indirect and explicit or direct tests of memory. Implicit tests are said to primarily reflect automatic or unconscious uses of memory, whereas explicit tests primarily reflect strategic or consciously-controlled uses of memory. Rather than identify different processes with different tasks, as is done by use of the implicit/explicit distinction, we have developed a method for separating the within-task contributions of unconscious and consciously-controlled influences. Our general approach starts with the assumption that unconscious or automatic influences and consciously-controlled influences make independent contributions to performance. Several experiments were reported to show the utility of the process-dissociation procedures. Among the findings of those experiments is that conditions traditionally associated with automaticity do have differential effects on consciously-controlled and unconscious (automatic) influences, as measured by the process-dissociation procedure. Other experiments were used to illustrate potential advantages of the process-dissociation procedure over reliance on implicit tests as a means of investigating unconscious influences. Still other experiments were briefly described to show that the process-dissociation procedure can be extended to separate the contributions of consciously-controlled and unconscious influences in a wide variety of domains. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A spatial modality effect in serial memory.

In 2 experiments, the authors tested whether the classical modality effect--that is, the stronger recency effect for auditory items relative to visual items--can be extended to the spatial domain. An order reconstruction task was undertaken with four types of material: visual-spatial, auditory-spatial, visual-verbal, and auditory-verbal. Similar serial position curves were obtained regardless of the nature of the to-be-remembered sequences, with the exception that a modality effect was found with spatial as well as with verbal materials. The results are discussed with regard to a number of models of short-term memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

TAP, implicit and explicit memory, and adult memory development.

This paper proposes a view of memory based on the notion of transfer appropriate processing (TAP) of Morris, Bransford, and Franks (1977). The author makes three specific assumptions to explain the disassociation between implicit and explicit memory. First, the author distinguishes between two memory organizing processes--integration and elaboration. Second, the author assumes that every kind of study task engages a combination of integrative and elaborative processing, but that some tasks focus primarily on integrative processing, and others focus more heavily on elaborative processing. Third, the author also assumes that every kind of test engages a combination of integrative and elaborative processing, but that implicit memory tests depend primarily on integrative processing, whereas explicit tests focus more heavily on elaborative processing. The long term goal of several on-going experiments is to learn more about the specific stimulus attributes that serve as cues for initialing/guiding integrative versus elaborative processing, and how these cues change across the life-span. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

When cross-modal spatial attention fails.

There is now convincing evidence that an involuntary shift of spatial attention to a stimulus in one modality can affect the processing of stimuli in other modalities, but inconsistent findings across different paradigms have led to controversy. Such inconsistencies have important implications for theories of cross-modal attention. The authors investigated why orienting attention to a visual event sometimes influences responses to subsequent sounds and why it sometimes fails to do so. They examined visual-cue-on-auditory-target effects in two paradigms--implicit spatial discrimination (ISD) and orthogonal cuing (OC)--that have yielded conflicting findings in the past. Consistent with previous research, visual cues facilitated responses to same-side auditory targets in the ISD paradigm but not in the OC paradigm. Furthermore, in the ISD paradigm, visual cues facilitated responses to auditory targets only when the targets were presented directly at the cued location, not when they appeared above or below the cued location. This pattern of results confirms recent claims that visual cues fail to influence responses to auditory targets in the OC paradigm because the targets fall outside the focus of attention. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Implicit false memory in the DRM paradigm: Effects of amnesia, encoding instructions, and encoding duration.

Recent studies with the Deese/Roediger–McDermott (Deese 1959; Roediger & McDermott, 1995) paradigm have revealed that amnesic patients do not only show impaired veridical memory, but also diminished false memory for semantically related lure words. Due to the typically used explicit retrieval instructions, however, this finding may reflect problems at encoding, at recollection, or both. Therefore, the present experiments examined implicit as well as explicit false memory in patients suffering from Korsakoff’s syndrome and controls. In Experiment 1, encoding instructions either focused on remembering individual list words, or on discovering semantic relationships among the words. In Experiment 2, different presentation durations were used. Results emphasize the distinction between automatic and intentional retrieval: Korsakoff patients’ veridical and false memory scores were diminished when explicit recollection was required, but not when memory was tested implicitly. Encoding manipulations only significantly affected veridical memory: Priming was reduced with thematic encoding, and explicit retrieval was facilitated when given more study time. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Intertrial Temporal Contextual Cuing: Association Across Successive Visual Search Trials Guides Spatial Attention.

Contextual cuing refers to the facilitation of performance in visual search due to the repetition of the same displays. Whereas previous studies have focused on contextual cuing within single-search trials, this study tested whether 1 trial facilitates visual search of the next trial. Participants searched for a T among Ls. In the training phase, the spatial layout on trial N=1 was predictive of the target location on trial N. In the testing phase, the predictive value was removed. Results revealed an intertrial temporal contextual cuing effect: Search speed became progressively shorter in the training phase, but it significantly lengthened during testing. The authors conclude that the visual system is capable of retaining spatial contextual memory established earlier to facilitate perception. (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)