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PubMed2006

A relative reward-strength algorithm for the hierarchical structure learning automata operating in the general nonstationary multiteacher environment.

A new learning algorithm for the hierarchical structure learning automata (HSLA) operating in the nonstationary multiteacher environment (NME) is proposed. The proposed algorithm is derived by extending the original relative reward-strength algorithm to be utilized in the HSLA operating in the general NME. It is shown that the proposed algorithm ensures convergence with probability 1 to the optimal path under a certain type of the NME. Several computer-simulation results, which have been carried out in order to compare the relative performance of the proposed algorithm in some NMEs against those of the two of the fastest algorithms today, confirm the effectiveness of the proposed algorithm.

Algorithms↗
PubMed2005

Neuroimaging studies of practice-related change: fMRI and meta-analytic evidence of a domain-general control network for learning.

Functional magnetic resonance imaging and a meta-analysis of prior neuroimaging studies were used to characterize cortical changes resulting from extensive practice and to evaluate a dual-processing account of the neural mechanisms underlying human learning. Three core predictions of the dual processing theory are evaluated: 1) that practice elicits generalized reductions in regional activity by reducing the load on the cognitive control mechanisms that scaffold early learning; 2) that these control mechanisms are domain-general; and 3) that no separate processing pathway emerges as skill develops. To evaluate these predictions, a meta-analysis of prior neuroimaging studies and a within-subjects fMRI experiment contrasting unpracticed to practiced performance in a paired-associate task were conducted. The principal effect of practice was found to be a reduction in the extent and magnitude of activity in a cortical network spanning bilateral dorsal prefrontal, left ventral prefrontal, medial frontal (anterior cingulate), left insular, bilateral parietal, and occipito-temporal (fusiform) areas. These activity reductions are shown to occur in common regions across prior neuroimaging studies and for both verbal and nonverbal paired-associate learning in the present fMRI experiment. The implicated network of brain regions is interpreted as a domain-general system engaged specifically to support novice, but not practiced, performance.

Adult↗
PubMed2001

Reconsideration of the role of the hippocampus in learned inhibition.

The purpose of this article is to reconsider the role of the hippocampus in learning tasks that require suppression or prevention of memories or responses. This type of learning has generally been referred to as inhibitory learning. Although early theories proposed that the hippocampus was important for inhibitory learning, these ideas have generally fallen out of favor. However, new developments in the conceptual understanding of inhibition along with recent experimental evidence require that we review these conceptual changes with regard to hippocampal function. We review three general categories of 'inhibition' that have been used with reference to hippocampal function: neural inhibition, inhibition of attention and associative or learned inhibition. We then consider recent developments in the field of animal learning that call for changes in the early conceptualizations of learned inhibition. Specifically, current findings suggest that different types of learning paradigms can yield conditioned inhibitors that are embedded in different associative structures, at least some of which can co-exist with conditioned excitation. Next we proceed to review a number of recent experiments from our laboratory as well as others that encouraged renewed interest in the role for the hippocampus in inhibitory learning. We then conclude by considering some of the implications of the idea that the hippocampus is involved with performance of conditioned responses based on cues that are concurrently embedded in inhibitory and excitatory associations.

Animals↗
PubMed1963

A further study of stimulus generalization following three-stimulus discrimination training.

A group of pigeons was trained in a Skinner box to peck for VI reinforcement when the key was illuminated by a monochromatic light of 540 or 580 mmu but were non-reinforced for responding to 560 mmu. Two control groups, differing in amount of training, received only the two positive stimuli. At the completion of training all Ss received generalization tests under extinction. Both control groups produced bi-modal generalization gradients with the peaks of responding at the S+ values. The post-discrimination gradient revealed peaks displaced from the S+ values in the direction away from the S-, low responding and increased steepness in the region of S- and a general elevation of the gradient.

Animals↗
PubMed2006

A hybrid SEM algorithm for high-dimensional unsupervised learning using a finite generalized Dirichlet mixture.

This paper applies a robust statistical scheme to the problem of unsupervised learning of high-dimensional data. We develop, analyze, and apply a new finite mixture model based on a generalization of the Dirichlet distribution. The generalized Dirichlet distribution has a more general covariance structure than the Dirichlet distribution and offers high flexibility and ease of use for the approximation of both symmetric and asymmetric distributions. We show that the mathematical properties of this distribution allow high-dimensional modeling without requiring dimensionality reduction and, thus, without a loss of information. This makes the generalized Dirichlet distribution more practical and useful. We propose a hybrid stochastic expectation maximization algorithm (HSEM) to estimate the parameters of the generalized Dirichlet mixture. The algorithm is called stochastic because it contains a step in which the data elements are assigned randomly to components in order to avoid convergence to a saddle point. The adjective "hybrid" is justified by the introduction of a Newton-Raphson step. Moreover, the HSEM algorithm autonomously selects the number of components by the introduction of an agglomerative term. The performance of our method is tested by the classification of several pattern-recognition data sets. The generalized Dirichlet mixture is also applied to the problems of image restoration, image object recognition and texture image database summarization for efficient retrieval. For the texture image summarization problem, results are reported for the Vistex texture image database from the MIT Media Lab.

Algorithms↗
PubMed1997

Can students learn clinical method in general practice? A randomised crossover trial based on objective structured clinical examinations.

OBJECTIVE: To determine whether students acquired clinical skills as well in general practice as in hospital and whether there was any difference in the acquisition of specific skills in the two environments. DESIGN: Randomised crossover trial. SUBJECTS AND SETTING: Annual intake of first year clinical students at one medical school. INTERVENTION: A 10 week block of general internal medicine, one half taught in general practice, the other in hospital. Students started at random in one location and crossed over after five weeks. OUTCOME MEASURES: Students' performance in two equivalent nine station objective structured clinical examinations administered at the mid and end points of the block: a direct comparison of the two groups' performance at five weeks; analysis of covariance, using their first examination scores as a covariate, to determine students' relative improvement over the second five weeks of their attachment. RESULTS: 225 students rotated through the block; all took at least one examination and 208 (92%) took both. For the first half of the year there was no significant difference in the students' acquisition of clinical skills in the two environments; later, however, students taught in general practice improved slightly more than those taught in hospital (P = 0.007). CONCLUSIONS: Students can learn clinical skills as well in general practice as in hospital; more work is needed to clarify where specific skills, knowledge, and attitudes are best learnt to allow rational planning of the undergraduate curriculum.

Clinical Competence↗
PubMed2004

Argument structure and the child's contribution to language learning.

One of the oldest questions in cognitive science asks whether children are able to learn language (or anything) because they are equipped with a very powerful general-purpose learning mechanism or because they are equipped with a domain-specific constrained language acquisition device. Recent advances in statistical approaches to language learning seem to boost the plausibility of general-purpose learning. However, in this article we propose that in the domain of verb learning, children rely more on their internally generated preconceptions about linguistic structure than on robust cues in the input, suggesting that at least in this aspect of language learning, domain-specific grammatical knowledge guides linguistic development.

Adolescent↗
PubMed1999

Risperidone versus haloperidol on secondary memory: can newer medications aid learning?

The introduction of the new generation of antipsychotic medications for the treatment of schizophrenia has been accompanied by a growing interest in the neurocognitive effects of these drugs. The present study compared the effects of risperidone and haloperidol on secondary memory in a group of treatment-resistant schizophrenia patients. The study design included a baseline phase and two double-blind phases in which patients were randomly assigned to medication under two different dose conditions (fixed dose and flexible dose). Secondary memory was assessed at baseline, fixed-dose, and flexible-dose phases, using the California Verbal Learning Test (CVLT). Six measures were selected, which formed three factors (general verbal learning ability, retention, and learning strategy). Risperidone-treated patients showed greater improvement than haloperidol-treated patients in general verbal learning ability, a finding characterized by significant treatment effects on CVLT measures of learning acquisition, recall consistency, and recognition memory. After controlling for benztropine status, differences on the measures of learning acquisition and recall consistency remained significant, and differences in recognition memory weakened slightly (p = 0.07). No significant treatment effects were noted on retention or learning strategy. These findings suggest that risperidone may exert a facilitating effect on the acquisition of new verbal information, an effect that does not appear to be due to the activation of semantic encoding strategies.

Adult↗
PubMed1984

Accuracy versus speed in the generalized effort of learning-disabled children.

Reinforcement of effortful performance in a given academic task has been found to increase the subsequent performance of other academic tasks. The learned-effort hypothesis assumes that individuals learn which dimensions of task performance are correlated with reinforcement of high effort, and generalize across tasks. Therefore, reinforcement of increased effort in a given dimension of one task should result in greater generalized effort in the same dimension of transfer performance than in another dimension. In accord with this view, preadolescent learning-disabled students who received points for high reading accuracy subsequently produced more accurate drawings and stories than did students whose points had been based upon high reading speed or upon mere completion of the reading task. Students who received points for high reading speed subsequently constructed stories more quickly than did children whose points had been based upon high reading accuracy or upon reading-task completion. Consistent with the more explicit and frequent feedback for accuracy than for speed in most academic tasks, generalized accuracy was much more durable than generalized speed.

Child↗
PubMed2004

Advances on BYY harmony learning: information theoretic perspective, generalized projection geometry, and independent factor autodetermination.

The nature of Bayesian Ying-Yang harmony learning is reexamined from an information theoretic perspective. Not only its ability for model selection and regularization is explained with new insights, but also discussions are made on its relations and differences from the studies of minimum description length (MDL), Bayesian approach, the bit-back based MDL, Akaike information criterion (AIC), maximum likelihood, information geometry, Helmholtz machines, and variational approximation. Moreover, a generalized projection geometry is introduced for further understanding such a new mechanism. Furthermore, new algorithms are also developed for implementing Gaussian factor analysis (FA) and non-Gaussian factor analysis (NFA) such that selecting appropriate factors is automatically made during parameter learning.

Algorithms↗
PubMedDate not supplied

Side-specificity of olfactory learning in the honeybee: generalization between odors and sides.

Honeybees (Apis mellifera) can be trained to associate an odor stimulus with a sucrose reward. The neural structures involved in the detection and integration of olfactory stimuli are represented bilaterally in the brain. Little is known about the respective roles of the two sides of the brain in olfactory learning. Does each side learn independently of the other, or do they communicate, and if so, to what extent and at what level of neural integration? We addressed these questions using the proboscis extension response (PER) conditioning paradigm applied in a preparation that allows the separation of the two input sides during olfactory stimulations. Bees conditioned to two odorants A and B, one being learned on each side (A+/B+ training), showed in extinction tests rather unspecific responses: They responded to both odorants on both sides. This could be attributable to either a transfer of the learned information between sides, or to a generalization between odorants on each side. By subjecting bees to conditioning on one side only (A+/0 training), we found that the learned information is indeed transferred between sides. However, when bees were trained explicitly to give opposite values to the two odorants on the two sides (A+B-/B+A- training), they showed clear side-specific response patterns to these odorants. These results are used in the elaboration of a functional model of laterality of olfactory learning and memory processing in the honeybee brain.

Animals↗
PubMed2006

General chemistry: expanding the learning outcomes and promoting interdisciplinary connections through the use of a semester-long project.

The laboratory component of a first-semester general chemistry course for science majors is described. The laboratory involves a semester-long project undertaken in a small-group format. Students are asked to examine whether plants grown in soil contaminated with lead take up more lead than those grown in uncontaminated soil. They are also asked to examine whether the acidity of the rainwater affects the amount of lead taken up by the plants. Groups are then given considerable independence in the design and implementation of the experiment. Once the seeds are planted, which takes about 4 wk into the term, several shorter experiments are integrated in before it is time to harvest and analyze the plants. The use of a project and small working groups allows for the development of a broader range of learning outcomes than occurs in a "traditional" general chemistry laboratory. The nature of these outcomes and some of the student responses to the laboratory experience are described. This particular project also works well at demonstrating the connections among chemistry, biology, geology, and environmental studies.

Adolescent↗
PubMed1985

Profiling, mimicking and masking the flavor of a selected rodenticide.

In Experiment 1, rats drank strychnine solution followed by an injection of LiCl. Generalization of learned strychnine avoidance to 4 non-toxic flavors was then assessed. Additional conditioning and generalization trials followed until 24 flavors had been presented. In Experiment 2, rats were conditioned to avoid individual flavors, or flavor mixtures concocted on the basis of avoidance generalization observed in Experiment 1. Tests followed for generalization of learned avoidance from the simple flavors to the mixtures, from the mixtures to the simple flavors, and from either to strychnine. In Experiment 3, two concentrations of NaCl were mixed with strychnine or one of the flavors (SOA) used in the previous experiments. These stimuli, as well as SOA alone, strychnine alone, and each of the NaCl concentrations, were presented to rats during conditioning. Generalization followed, as in the previous experiments. In Experiment 1, strychnine avoidance generalized to 'bitter' flavors (ps less than 0.01). In Experiment 2, avoidance of flavor mixtures generalized more strongly to strychnine than did learned avoidance of simple flavors (ps less than 0.01). In Experiment 3, NaCl masked or otherwise suppressed the 'bitter' flavor of strychnine or SOA insofar as no groups conditioned with a 'bitter'-salt mixture generalized avoidance to 'bitter' alone (ps less than 0.01). Rats are therefore capable of recognizing the flavor components of strychnine. Moreover, when these components are mixed in proportion to the degree of generalized avoidance, a mimic (either in terms of flavor characteristics or perceived intensity) of strychnine is obtained. Avoidance learning appears useful in the development of rodenticide baits and pre-bait formulations.

Animals↗
PubMed2005

The evolution of domain-general mechanisms in intelligence and learning.

For both humans and animals, domain-general mechanisms are fallible but powerful tools for attaining evolutionary goals (e.g., resources) in uncertain, novel environments that were not recurrent features of the environment of evolutionary adaptedness. Domain-general mechanisms interact in complex ways with domain-specific, information-encapsulated modules, most importantly by manipulating information obtained from various modules in attempting to solve novel problems. Mechanisms of general intelligence, particularly the executive functions of working memory, underlie analogical reasoning as well as the decontextualization processes that are central to human thought. Although there is a variety of evolved, special purpose learning devices, learning is also characterized by domain-general mechanisms that are able to achieve evolutionary goals by making novel and serendipitous associations with environmental cues.

Animals↗
PubMed1990

The learning needs in diabetes of general practitioners.

The aim of the study was to determine the learning needs of General Practitioners (GPs) in diabetes. A postal questionnaire was sent to all GPs in South East Thames Region (England). The level of interest in continuing professional education in diabetes is sufficient to merit production of tailored learning materials and opportunities. Eighty-three percent of GPs would definitely or probably avail themselves of the opportunity even if they did have to pay. This percentage represents a figure of over 780 GPs. They are most keen to learn the clinical and other skills associated with diabetes and its management. A large number, 71%, requested education on retinal examination and adjustment of insulin, 56% on adjustment of tablet therapy, and 51% on the management of children with diabetes. Individual study materials, backed up by small group meetings and video material would be the most appreciated format. A course of study divided into half-hourly periods adding up to a total of about 5 h might be the most widely acceptable format. GPs would most like to study with other GPs from local practices and with hospital staff. Group work might best be designed to incorporate both an experienced GP, if one were available, and a consultant. The materials themselves might also best be designed and written by such a partnership.

Diabetes Mellitus↗
PubMed2004

Teaching anatomy without cadavers.

BACKGROUND: Anatomy learning is generally seen as essential to medicine, and exposure to cadavers is generally seen as essential to anatomy learning around the world. Few voices dissenting from these propositions can be identified. AIMS: This paper aims to consider arguments relating to the use of cadavers in anatomy teaching, and to describe the rationale behind the decision of a new UK medical school not to use cadaveric material. DISCUSSION: First, the background to use of cadavers in anatomy learning is explored, and some general educational principles are explored. Next, arguments for the use of human cadaveric material are summarised. Then, possible arguments against use of cadavers, including educational principles as well as costs, hazards and practicality, are considered. These are much less well explored in the existing literature. Next, the rationale behind the decision of a new UK medical school not to use cadaveric material is indicated, and the programme of anatomy teaching to be employed in the absence of the use of human remains is described. Curriculum design and development, and evaluation procedures, are briefly described. Issues surrounding pathology training by autopsy, and postgraduate training in surgical anatomy, are not addressed in this paper. FUTURE DIRECTIONS: Evidence relating to the effect on medical learning by students not exposed to cadavers is scant, and plainly opportunities will now arise through our programme to gather such evidence. We anticipate that this discussion paper will contribute to an ongoing debate, in which virtually all previous papers on this topic have concluded that use of cadavers is essential to medical learning.

Anatomy↗