Spatial attention and implicit sequence learning: Evidence for independent learning of spatial and nonspatial sequences.

This research investigated whether regular spatial orienting sequences can be learned implicitly and independently of response requirements. In a new version of a serial response task introduced by M. J. Nissen and P. Bullemer (1987) participants had to discriminate between objects that could occur at different locations. Independent sequences determined the succession of locations and objects. Even participants who were not aware of any regularities exhibited evidence for learning of both sequences (Experiment 1). Experiment 2 showed that the joint learning of spatial and object sequences was as efficient as learning of single sequences and that it even occurred when learning required memory for past sequence elements and attention was blocked through a secondary tone-counting task. Results are consistent with the idea that independent systems may exist for the implicit acquisition of spatial and nonspatial regularities. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Impaired implicit learning in schizophrenia.

Schizophrenia patients consistently show deficits on tasks of explicit learning and memory. In contrast, their performance on implicit processing tasks often appears to be relatively intact, although most studies have focused on implicit learning of motor skills. This study evaluated implicit learning in 59 medicated schizophrenia outpatients and 43 controls using 2 different cognitive skill tasks. Participants completed a probabilistic classification task to assess procedural habit learning and an artificial grammar task to assess incidental learning of complex rule-based knowledge, as well as an explicit verbal learning and memory task. In addition to performing worse than controls on the explicit learning task, patients showed worse overall performance on the probabilistic classification task, which involves gradual learning through trial-by-trial performance feedback. However, patients and controls showed similar levels of learning on the artificial grammar task, suggesting a preserved ability to acquire complex rule-based knowledge in the absence of performance feedback. Discussion focuses on possible explanations for schizophrenia patients' poor probabilistic classification task performance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Contextual cueing: implicit learning and memory of visual context guides spatial attention

Global context plays an important, but poorly understood, role in visual tasks. This study demonstrates that a robust memory for visual context exists to guide spatial attention. Global context was operationalized as the spatial layout of objects in visual search displays. Half of the configurations were repeated across blocks throughout the entire session, and targets appeared within consistent locations in these arrays. Targets appearing in learned configurations were detected more quickly. This newly discovered form of search facilitation is termed contextual cueing. Contextual cueing is driven by incidentally learned associations between spatial configurations (context) and target locations. This benefit was obtained despite chance performance for recognizing the configurations, suggesting that the memory for context was implicit. The results show how implicit learning and memory of visual context can guide spatial attention towards task-relevant aspects of a scene.     

Role of implicit and explicit processes in learning from examples: A synergistic effect.

Four experiments are reported in which subjects gained extensive experience with artificial grammars in explicit and implicit processing tasks. Results indicate that (a) implicit processing was sufficient for learning a finite state grammar but was inadequate for learning another type of grammar based on logical rules. (b) Subjects were able to communicate some of their implicit knowledge of the grammars to another person. (c) Consistent with rule induction but not memory array models of learning, verbal protocols indicated there was no tendency to converge on the same set of cues used to identify valid strings. (d) A synergistic learning effect occurred when both implicit and explicit processing tasks were used in grammar based on logical rules but not in the finite state grammar. A theoretical framework is proposed in which implicit learning is conceptualized as an automatic, memory-based mechanism for detecting patterns of family resemblance among exemplars. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Intact implicit habit learning in Alzheimer's disease.

Habit learning refers to the incremental implicit learning of associations. Patients with Alzheimer's disease (AD) exhibit deficits in explicit memory and in conceptual implicit memory tasks that rely on the cortical areas damaged in AD. The authors tested patients with AD and controls on a probabilistic classification task in which participants implicitly acquire cue-outcome associations. Both groups showed evidence of learning across 50 trials, and performance did not differ significantly between the groups. In contrast, patients with AD exhibited a profound impairment in explicit memory for the testing episode. These results are consistent with the idea that habit learning relies on subcortical structures, including the basal ganglia, and is independent of the medial temporal and cortical areas damaged in AD. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Developmental differences in implicit learning of spatial context.

The authors examined whether a form of implicit memory that has been unambiguously dissociated from conscious awareness--learning of spatial context on the contextual cuing task introduced by M. M. Chun and Y. Jiang (1998)--is mature in childhood as predicted by an evolutionary view of cognition. School-aged children did not show reliable learning relative to adults who performed the same version of the task or another version that slowed responses to match those of children. Thus, unreliable learning in childhood was mediated by immature implicit representations of spatial context rather than by slower baseline response speed. The present finding is inconsistent with the prediction of the evolutionary view of cognition but consistent with incomplete maturation of medial temporal lobes known to mediate contextual learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Statistical structure and implicit serial learning.

In serial reaction time (RT) tasks, RT decreases faster with practice when a short sequence of trials is repeated continuously than when the sequence of trials is random (e.g., M. J. Nissen & P. Bullemer, 1987). Learning is implicit because Ss are not asked to learn the sequence and they often seem unaware of it. Relative to a random sequence, the repeating sequence imposes extreme statistical constraints. The present research examined the relation between these statistical constraints and implicit serial learning. Two experiments showed that the greater the statistical structure, the greater the reduction in RT with practice. Statistical structure was manipulated by varying the structure of a repeating sequence (Exp 1) and by varying the degree to which sequences approximated the statistical structure of a repeating sequence (Exp 2). The implications of these results for theories of implicit serial learning are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Variability of practice and implicit motor learning.

The authors examined variable versus constant practice effects on implicit motor learning in continuous pursuit tracking. On every trial, two thirds of each trial consisted of random patterns, whereas one third was always repeated. The tracking patterns (including the repeated segment) were linearly scaled in absolute amplitude (Experiment 1) or overall speed (Experiments 1 and 2), with the scaling factors being either varied or constant across trials for different groups. The repeated segment was generally produced more accurately than the 2 random segments on retention tests and on transfer tests with novel scalings—and without participants' awareness of the repetition—suggesting that the repeated segment was learned implicitly. Also, learning was generally enhanced by variable practice, as compared with constant practice, suggesting that the advantages of variable over constant practice found in discrete tasks are generalizable to feedback-regulated tracking tasks. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Selective attention in animal discrimination learning.

2 classes of experiment on the role of attention in discrimination learning are reviewed: (a) Investigations of the effect of attention on the amount learned about different cues have been interpreted as disproving noncontinuity theory (according to which animals attend to only 1 cue at a time). The fact that animals learn something about a 2nd cue, however, does not prove that attention has no effect on learning, and more recent evidence shows that it does. (b) If animals do not automatically attend to all cues, part of what they must learn in order to solve a discrimination problem is to attend to the relevant cue. Experiments on the acquired distinctiveness of cues, transfer along a continuum, and reversal learning provide evidence for the importance of such classificatory learning. (155 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Automatic attention does not equal automatic fear: Preferential attention without implicit valence.

Theories of nonassociative fear acquisition hold that humans have an innate predisposition for some fears, such as fear of snakes and spiders. This predisposition may be mediated by an evolved fear module (?hman & Mineka, 2001) that responds to basic perceptual features of threat stimuli by directing attention preferentially and generating an automatic fear response. Visual search and affective priming tasks were used to examine attentional processing and implicit evaluation of snake and spider pictures in participants with different explicit attitudes; controls (n = 25) and snake and spider experts (n = 23). Attentional processing and explicit evaluation were found to diverge; snakes and spiders were preferentially attended to by all participants; however, they were negative only for controls. Implicit evaluations of dangerous and nondangerous snakes and spiders, which have similar perceptual features, differed for expert participants, but not for controls. The authors suggest that although snakes and spiders are preferentially attended to, negative evaluations are not automatically elicited during this processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The neural correlates of implicit sequence learning in schizophrenia.

Twenty-seven schizophrenia spectrum patients and 25 healthy controls performed a probabilistic version of the serial reaction time task (SRT) that included sequence trials embedded within random trials. Patients showed diminished, yet measurable, sequence learning. Postexperimental analyses revealed that a group of patients performed above chance when generating short spans of the sequence. This high-generation group showed SRT learning that was similar in magnitude to that of controls. Their learning was evident from the very 1st block; however, unlike controls, learning did not develop further with continued testing. A subset of 12 patients and 11 controls performed the SRT in conjunction with positron emission tomography. High-generation performance, which corresponded to SRT learning in patients, correlated to activity in the premotor cortex and parahippocampus. These areas have been associated with stimulus-driven visuospatial processing. Taken together, these results suggest that a subset of patients who showed moderate success on the SRT used an explicit stimulus-driven strategy to process the sequential stimuli. This adaptive strategy facilitated sequence learning but may have interfered with conventional implicit learning of the overall stimulus pattern. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The role of attention during encoding in implicit and explicit memory.

In 5 experiments, participants read study words under conditions of divided or full attention. Dividing attention reduced performance on the general knowledge test, a conceptual implicit test of memory. Likewise, dividing attention reduced conceptual priming on the word association task, as well as on a matched explicit test, associate-cued recall. In contrast, even very strong division of attention did not reduce perceptual priming on word-fragment completion, although it did reduce recall on the matched explicit test of word-fragment-cued recall. Finally, dividing attention reduced recall on the perceptual explicit tests of graphemic-cued recall and graphemic recognition. The results indicate that perceptual implicit tests rely minimally on attention-demanding encoding processes relative to other types of memory tests. The obtained pattern of dissociations is not readily accommodated by the transfer-appropriate-processing (TAP) account of implicit and explicit memory. Potential extensions of the TAP view are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Psychometric intelligence dissociates implicit and explicit learning.

The hypothesis that performance on implicit learning tasks is unrelated to psychometric intelligence was examined in a sample of 605 German pupils. Performance in artificial grammar learning, process control, and serial learning did not correlate with various measures of intelligence when participants were given standard implicit instructions. Under an explicit rule discovery instruction, however, a significant relationship between performance on the learning tasks and intelligence appeared. This finding provides support for Reber's hypothesis that implicit learning, in contrast to explicit learning, is independent of intelligence, and confirms thereby the distinction between the 2 modes of learning. However, because there were virtually no correlations among the 3 learning tasks, the assumption of a unitary ability of implicit learning was not supported. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Role of attention in face encoding.

Ss studied faces in a full- or a divided-attention condition and then received a recognition test that included old faces, new faces constructed by combining facial features from previously studied faces ("conjunction faces"), and partly or completely new faces. Full- but not divided attention Ss responded "old" more often to old than to conjunction faces; all Ss responded "old" to these faces more often than to partially or completely new faces. Thus it is less attentionally demanding to encode facial features than it is to encode their interrelations. Dividing attention had identical effects on an incidental and an intentional learning group. Exp 3 demonstrated that dividing attention primarily affected explicit recollection rather than stimulus familiarity. (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)     

Perceptually based implicit learning in severe closed-head injury patients.

This study suggests that perceptually based implicit learning may either be preserved following a severe closed-head injury (CHI) or recover within the 1st year. Nineteen severe CHI patients and 19 controls searched visual matrices and indicated the quadrant location of a target. Participants were exposed to the following covariation pattern: AAAABAAA. For Covariation A blocks, the matrices systematically co-occurred with a unique location of the target. This relationship was altered for the B block. Despite CHI participants' overall slower response times (RTs), both groups demonstrated the expected decline in RTs across the first 4 Covariation A blocks followed by an increase when the covariation changed. Both groups also exhibited retention of their learning after a 20-min delay. Explicit knowledge tests indicated that participants lacked awareness for the covariation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Unconscious learning of rules: Comment on Reber's analysis of implicit learning.

A. S. Reber's (see record 1989-38920-001) research is contrasted with studies of unconscious process in which discrimination procedures were used to establish the influence of subliminal stimuli. In particular, it is noted that Reber's procedures do not permit him to distinguish between awareness and the state of being aware. In principle, discrimination procedures can be used to establish the nature of the subject's awareness in experiments designed to study the acquisition of allegedly unconscious rules. Until this is done, the unconscious status of the knowledge acquired in these experiments remains indeterminate. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Response–effect learning as a major component of implicit serial learning.

Implicit response–effect learning was examined in 2 experiments, using a visual search version of the serial reaction time task introduced by M. J. Nissen and P. Bullemer (1987). In Experiment 1, the relation between the response to the current stimulus and the location of the stimulus on the next trial (i.e., effect) was varied systematically. In Experiment 2, both the frequency of the association between stimuli and responses and the frequency of the association between responses and effects were manipulated. Only the frequency of the response–effect relation influenced learning. These results indicate that response–effect learning is an important component of serial learning. It is argued that response–effect relations constitute the initial implicit component of learning in serial reaction time tasks. From this implicit knowledge, knowledge about the stimulus sequence as well as the response sequence develops later. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Qualitative differences between implicit and explicit sequence learning.

Four experiments investigate the differences between implicit and explicit sequence learning concerning their resilience to structural and superficial task changes. A superficial change that embedded the SRT task in the context of a selection task, while maintaining the sequence, did selectively hinder the expression of implicit learning. In contrast, a manipulation that maintained the task surface, but decreased the sequence validity, affected the expression of learning specifically when it was explicit. These results are discussed in the context of a dynamic framework (Cleeremans & Jime'nez, 2002), which assumes that implicit knowledge is specially affected by contextual factors and that, as knowledge becomes explicit, it allows for the development of relevant metaknowledge that modulates the expression of explicit knowledge. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of interest on attention and learning.

The effects of interest on the allocation of attention to, and the learning of, written material were investigated in this study. Twenty-three college students read 72 sentences that had been previously rated for interest. The sentences were presented on an Apple IIe microcomputer that recorded two measures of attention: sentence reading time and reaction time to a secondary task. After sentence presentation, students were given a cued recall test of the material. Results showed that although interesting sentences were learned much better, less attention was allocated to them; hence attention did not serve as a causal mediator between interest and learning. Results also indicated that subjects engaged in some strategy independent of attention to learn the interesting material. The results are discussed in terms of the development of strategies for efficient reading. (PsycINFO Database Record (c) 2010 APA, all rights reserved)