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PubMed2004

Failure to construct and transfer correct representations across probability problems.

Previous studies carried out on "purely random" situations (with dice or poker chips) show the difficulties encountered by people in such situations, however simple they may be. In fact, in this type of situation, prior knowledge guides spontaneous representations, and the "errors" observed could be explained by the activation of "implicit models" which form the basis of erroneous representations. 42 statistically naïve undergraduates were given several variants of a probability problem on which errors are common. In a learning phase, subjects were given four problems involving geometric figures which were pairwise related by complementarity and equivalence relations. In a subsequent transfer phase, they were given a fifth problem involving poker chips, which was structurally isomorphic to the fourth geometric-figures problem. The findings show that people do not realize the relations between problems, and that transfer occurred only for the subset of subjects who performed correctly on the training problems of the learning phase. These results appear to have some significant implications in teaching mathematical concepts.

Adolescent↗
PubMed2000

Striatum forever, despite sequence learning variability: a random effect analysis of PET data.

This PET study is concerned with the what, where, and how of implicit sequence learning. In contrast with previous studies imaging the serial reaction time (SRT) task, the sequence of successive locations was determined by a probabilistic finite-state grammar. The implicit acquisition of statistical relationships between serially ordered elements (i.e., what) was studied scan by scan, aiming to evidence the brain areas (i.e., where) specifically involved in the implicit processing of this core component of sequential higher-order knowledge. As behavioural results demonstrate between- and within-subjects variability in the implicit acquisition of sequential knowledge through practice, functional PET data were modelled using a random-effect model analysis (i.e., how) to account for both sources of behavioural variability. First, two mean condition images were created per subject depending on the presence or not of implicit sequential knowledge at the time of each of the 12 scans. Next, direct comparison of these mean condition images provided the brain areas involved in sequential knowledge processing. Using this approach, we have shown that the striatum is involved in more than simple pairwise associations and that it has the capacity to process higher-order knowledge. We suggest that the striatum is not only involved in the implicit automatization of serial information through prefrontal cortex-caudate nucleus networks, but also that it plays a significant role for the selection of the most appropriate responses in the context created by both the current and previous stimuli, thus contributing to better efficiency and faster response preparation in the SRT task.

Adult↗
PubMed2000

Implicit memory for auditorily presented threatening stimuli: a process-dissociation approach.

The investigation of unconscious cognition involves especially problems with the methodology of measuring implicit and explicit proportions of different task performances. In this study the process dissociation procedure of Jacoby and its modification within the multinomial modelling framework for an indirect word-nonword-discrimination task is applied to a sample of 45 healthy students. The paradigm includes acoustically presented stimuli. During a learning phase, subjects listened to a series of neutral and threatening words. Performance was tested by letting subjects decide whether a presented stimulus (masked with white noise at signal-noise ratio of -17 dB or unmasked) had been a word or a nonword. Within this paradigm, implicit cognition occurs when (a) a word is more probably correctly recognized as "word" after presentation during the learning phase (typical priming effect) or when (b) a nonword derived from a word is more probably falsely recognized as "word" after its corresponding word had been presented during the learning phase (effect of implicit cognition given perceptual fluency). Frequencies for hits and false alarms were analyzed within the multinomial model which allows estimating parameters for the correct discrimination of words (c), the response bias (b), the classical priming effect (u1), and the parameter for the priming effect of "old" nonwords (u2). Under masked stimuli the multinomial model showed implicit cognition, an effect not equally found for neutral and threatening words. Threatening words exhibited a significantly higher portion of implicit cognition than neutral ones. Given the statistical complexity of multinomial models, the application of this method was explained in detail.

Acoustic Stimulation↗
PubMed2002

Is implicit learning spared in amnesia? Rule abstraction and item familiarity in artificial grammar learning.

We examined implicit learning of an artificial grammar in amnesic and control participants. The "biconditional" grammar used to generate study and test strings allows two potential sources of judgements in artificial grammar learning to be unconfounded: participants could either learn the abstract biconditional rules or could learn about the distributional statistics of the surface elements (e.g. bigrams) composing the study items. Test strings varied these two sources orthogonally. We found no evidence of abstract rule learning either in the control or amnesic groups. In contrast, both groups learned about the surface elements and tended to call test strings "grammatical" when they were composed of familiar bigrams. However, this sensitivity to bigram familiarity was significantly reduced in the amnesic compared to the control group. The results challenge the claim that implicit learning is intact in amnesia.

Amnesia↗
PubMed1996

N-tuple Regression Network.

N-tuple neural networks (NTNNs) have been successfully applied to both pattern recognition and function approximation tasks. Their main advantages include a single layer structure, capability of realizing highly non-linear mappings and simplicity of operation. In this work a modification of the basic network architecture is presented, which allows it to operate as a non-parametric kernel regression estimator. This type of network is inherently capable of approximating complex probability density functions (pdfs) and, in the limiting sense, deterministic arbitrary function mappings. At the same time, the regression network features a powerful one-pass training procedure and its learning is statistically consistent. The major advantage of utilizing the N-tuple architecture as a regression estimator is the fact that in this realization the training set points are stored by the network implicitly, rather than explicitly, and thus the operation speed remains constant and independent of the training set size. Therefore, the network performance can be guaranteed in practical implementations. Copyright 1996 Elsevier Science Ltd

Journal Article↗
PubMed2005

Priming for novel between-word associations in patients with organic amnesia.

Ten amnesic patients of various etiologies and 10 matched normal controls participated in this study. On 2 consecutive days, subjects studied 30 novel word-word associations 6 times. Using a cued recall task, we assessed episodic learning and delayed retention of the study material immediately after each study phase and again 24 hr after the final study phase. Further, we evaluated implicit memory for new between-word associations by means of an automatic relational priming paradigm immediately after the delayed cued recall trial. Amnesic patients performed poorly on the cued recall task. Moreover, in the overall group of amnesics the priming effect failed to reach statistical significance. When the overall group of amnesics was split according to mean performance on the cued recall task, those in the low performer subgroup--comprised of 6 patients with direct or indirect involvement of the hippocampi--were particularly poor at episodically remembering the associations and did not reveal any relational priming. These data support the hypothesis of similar impairment of new episodic and implicit learning in amnesic patients and suggest that the hippocampus is crucial for both kinds of new learning.

Adult↗
PubMed2006

Attention modulates the learning of multiple contingencies.

We employed a novel version of the serial reaction time task to test the idea that human implicit learning allows the simultaneous learning of multiple independent contingencies and that this learning may proceed in the absence of attention. Using probabilistic sequences, we showed that both a primary sequence (the focus of the experimental task) and a statistically independent secondary sequence could be learned across 4,800 target localization trials, provided the perceptual load of the primary task was low. However, learning of the secondary sequence was abolished under conditions of high perceptual load. These findings suggest that there are attentional limitations on the learning of multiple contingencies.

Attention↗
PubMed2003

Evaluating the evidence for implicit perceptual learning: a re-analysis of Farrow and Abernethy (2002).

I present a re-analysis of the data from Farrow and Abernethy's (2002) study of implicit perceptual training in tennis. I argue that there are several weaknesses and mistakes in the original analysis, which, when rectified, lead to a fundamentally different set of conclusions to those given in the original paper. Specifically, there are significant group differences in anticipatory performance before the intervention that make subsequent between-group comparisons at specific occlusion points problematic. Second, in contrast to what is reported in the original paper, the explicit learning intervention resulted in a significant improvement in performance. In addition, a comparison of the effects of the different interventions indicates that the placebo group demonstrated the largest mean improvement in anticipation for the four occlusion points up to racquet-ball impact. Third, the non-significant change in performance over a 32-day retention period indicates that any improvements in performance were retained, not lost, over this period of time. Following a re-analysis of the original data, I conclude that Farrow and Abernethy's study provides no evidence that an implicit perceptual training paradigm improves anticipatory performance more than either an explicit learning paradigm or, indeed, an intervention involving mere observation of tennis matches.

Data Interpretation, Statistical↗
PubMedDate not supplied

Effects of program design on the professional socialization of RN-BSN students.

The purpose of this study was to examine effects of program design on the bureaucratic and professional role conceptions of registered nurses in baccalaureate nursing programs. Attention to how programs are set up and function has relevance for theory and practice and enables improving frameworks for program planning. The study design embodied qualitative and quantitative elements and used six processes of socialization in organizations as a conceptual guide. Qualitative data collection concerned comparative case studies of three baccalaureate nursing programs and data analysis included narratives detailing program organization and describing student experience. Quantitative matter involved mailed questionnaires to determine graduates' bureaucratic, professional, and service role conceptions. Data analysis (analysis of variance) revealed statistically significant differences in role conceptions (F[3.56] = 4.51) of registered nurses graduating from different baccalaureate programs in nursing. Indications are that nursing programs can be set up to produce equal education and reach certain stated outcomes, yet implicit program processes can impact student learning.

Adult↗
PubMed2000

Incremental validity of WISC-III profile elevation, scatter, and shape information for predicting reading and math achievement.

The use of cognitive subtest profiles to hypothesize about children's learning strengths and weaknesses implicitly assumes that subtest profiles are predictive of academic performance. To test this assumption, Wechsler Intelligence Scale for Children-Third Edition (WISC-III) subtest profiles were decomposed into elevation, scatter, and shape components and sequentially regressed onto reading and math achievement scores for 1,118 nonexceptional and 538 exceptional students. Profile elevation was statistically and practically significant for both exceptional (R = .36-.61) and nonexceptional (R = .72-.75) students. Profile scatter did not aid in the prediction of achievement. Profile shape accounted for an additional 5%-8% of the variance in achievement measures. It was concluded that using WISC-III subtest scatter and shape to predict academic performance was not supported by the accumulated scientific evidence.

Adolescent↗
PubMed2005

A fuzzy reinforcement learning approach to power control in wireless transmitters.

We address the issue of power-controlled shared channel access in wireless networks supporting packetized data traffic. We formulate this problem using the dynamic programming framework and present a new distributed fuzzy reinforcement learning algorithm (ACFRL-2) capable of adequately solving a class of problems to which the power control problem belongs. Our experimental results show that the algorithm converges almost deterministically to a neighborhood of optimal parameter values, as opposed to a very noisy stochastic convergence of earlier algorithms. The main tradeoff facing a transmitter is to balance its current power level with future backlog in the presence of stochastically changing interference. Simulation experiments demonstrate that the ACFRL-2 algorithm achieves significant performance gains over the standard power control approach used in CDMA2000. Such a large improvement is explained by the fact that ACFRL-2 allows transmitters to learn implicit coordination policies, which back off under stressful channel conditions as opposed to engaging in escalating "power wars."

Algorithms↗
PubMed1995

Explicit and procedural memory in Parkinson's disease.

One of the aims of cognitive psychology is to breakdown complex tasks into their most basic components. The components of explicit (declarative) and implicit (procedural) memory were thus analyzed in undemented, non-depressed Parkinsonian patients under anti-Parkinsonian treatment, and compared with young and elderly healthy subjects. Three series of experiments were conducted in 61 patients in total. Statistically significant results revealed an impairment of explicit memory (verbal recall of words and drawings) with preserved recall of faces, in Parkinsonians. Implicit memory was also deficient, only in association tests (sound-form; arithmetical alphabet) and maze tests. Braille reading tests and Toronto tower tests did not discriminate between Parkinsonians and elderly subjects. Lastly, analyzing learning and automation revealed a dysfunctioning in Parkinsonian patients. All these data indicate a dysregulation of the cortical-sub-cortical systems, not essentially pre-frontal, and not necessarily dopaminergic. Cognitively, it appears that procedural and implicit memories should be dissociated conceptually.

Adult↗
PubMed1997

A confirmatory factor analysis of the structure of tacit knowledge in nursing.

The purpose of this study was to examine the structure of tacit knowledge in the nursing profession. Using research in implicit learning and practical intelligence as a theoretical framework, a paper-and-pencil measure of tacit knowledge for nurses was developed and refined. Five models, each representing an established theory of traditional intelligence, were compared in terms of fit to the data. The results of the confirmatory factor analysis suggest that Model 3, a hierarchical model of intelligence, was the most plausible representation of tacit knowledge in nursing. The results indicate that the portion of managerial decision making learned implicitly on the job is mainly accounted for by managing tasks and others. Suggestions for nursing education include teaching effective strategies for managing tasks, such as handling increased workloads, establishing priorities, and delegating responsibility.

Decision Making↗
PubMedDate not supplied

Recursive self-organizing maps.

This paper explores the combination of self-organizing map (SOM) and feedback, in order to represent sequences of inputs. In general, neural networks with time-delayed feedback represent time implicitly, by combining current inputs and past activities. It has been difficult to apply this approach to SOM, because feedback generates instability during learning. We demonstrate a solution to this problem, based on a nonlinearity. The result is a generalization of SOM that learns to represent sequences recursively. We demonstrate that the resulting representations are adapted to the temporal statistics of the input series.

Algorithms↗
PubMed2006

Patients with Parkinson's disease learn to control complex systems-an indication for intact implicit cognitive skill learning.

Implicit memory and learning mechanisms are composed of multiple processes and systems. Previous studies demonstrated a basal ganglia involvement in purely cognitive tasks that form stimulus response habits by reinforcement learning such as implicit classification learning. We will test the basal ganglia influence on two cognitive implicit tasks previously described by Berry and Broadbent, the sugar production task and the personal interaction task. Furthermore, we will investigate the relationship between certain aspects of an executive dysfunction and implicit learning. To this end, we have tested 22 Parkinsonian patients and 22 age-matched controls on two implicit cognitive tasks, in which participants learned to control a complex system. They interacted with the system by choosing an input value and obtaining an output that was related in a complex manner to the input. The objective was to reach and maintain a specific target value across trials (dynamic system learning). The two tasks followed the same underlying complex rule but had different surface appearances. Subsequently, participants performed an executive test battery including the Stroop test, verbal fluency and the Wisconsin card sorting test (WCST). The results demonstrate intact implicit learning in patients, despite an executive dysfunction in the Parkinsonian group. They lead to the conclusion that the basal ganglia system affected in Parkinson's disease does not contribute to the implicit acquisition of a new cognitive skill. Furthermore, the Parkinsonian patients were able to reach a specific goal in an implicit learning context despite impaired goal directed behaviour in the WCST, a classic test of executive functions. These results demonstrate a functional independence of implicit cognitive skill learning and certain aspects of executive functions.

Aged↗
PubMed2005

A unified framework for image retrieval using keyword and visual features.

In this paper, a unified image retrieval framework based on both keyword annotations and visual features is proposed. In this framework, a set of statistical models are built based on visual features of a small set of manually labeled images to represent semantic concepts and used to propagate keywords to other unlabeled images. These models are updated periodically when more images implicitly labeled by users become available through relevance feedback. In this sense, the keyword models serve the function of accumulation and memorization of knowledge learned from user-provided relevance feedback. Furthermore, two sets of effective and efficient similarity measures and relevance feedback schemes are proposed for query by keyword scenario and query by image example scenario, respectively. Keyword models are combined with visual features in these schemes. In particular, a new, entropy-based active learning strategy is introduced to improve the efficiency of relevance feedback for query by keyword. Furthermore, a new algorithm is proposed to estimate the keyword features of the search concept for query by image example. It is shown to be more appropriate than two existing relevance feedback algorithms. Experimental results demonstrate the effectiveness of the proposed framework.

Algorithms↗
PubMed2006

Cracking the language code: neural mechanisms underlying speech parsing.

Word segmentation, detecting word boundaries in continuous speech, is a critical aspect of language learning. Previous research in infants and adults demonstrated that a stream of speech can be readily segmented based solely on the statistical and speech cues afforded by the input. Using functional magnetic resonance imaging (fMRI), the neural substrate of word segmentation was examined on-line as participants listened to three streams of concatenated syllables, containing either statistical regularities alone, statistical regularities and speech cues, or no cues. Despite the participants' inability to explicitly detect differences between the speech streams, neural activity differed significantly across conditions, with left-lateralized signal increases in temporal cortices observed only when participants listened to streams containing statistical regularities, particularly the stream containing speech cues. In a second fMRI study, designed to verify that word segmentation had implicitly taken place, participants listened to trisyllabic combinations that occurred with different frequencies in the streams of speech they just heard ("words," 45 times; "partwords," 15 times; "nonwords," once). Reliably greater activity in left inferior and middle frontal gyri was observed when comparing words with partwords and, to a lesser extent, when comparing partwords with nonwords. Activity in these regions, taken to index the implicit detection of word boundaries, was positively correlated with participants' rapid auditory processing skills. These findings provide a neural signature of on-line word segmentation in the mature brain and an initial model with which to study developmental changes in the neural architecture involved in processing speech cues during language learning.

Adult↗
PubMed1997

Age differences in implicit learning of higher order dependencies in serial patterns.

3 experiments examined serial pattern learning in younger and older adults. Unlike the usual repeating pattern, the sequences alternated between events from a repeating pattern and those determined randomly. The results indicated that no one was able to describe the regularity, but with practice every individual in all 3 age groups (including old old) became faster, more accurate, or both, on pattern trials than on random trials. Although this indicates that adults of all ages are able to learn second-order statistical dependencies in a sequence, age-related deficits were obtained in the magnitude of pattern learning. There were also age differences in what was learned, with only younger people revealing sensitivity to higher order statistical dependencies in the sequence. In addition, whereas younger people revealed evidence of their pattern learning in a subsequent conceptually driven production test, young-old and old-old people did not.

Adult↗