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PubMed2005

Visual working memory in decision making by honey bees.

The robustness and plasticity of working memory were investigated in honey bees by using a delayed matching-to-sample (DMTS) paradigm. The findings are summarized as follows: first, performance in the DMTS task decreases as the duration between the presentation of the sample stimulus and the presentation of the comparison stimuli is increased. This decrease is well approximated by an exponential decay function. Performance is significantly better than random-choice level even at delays as long as 5 sec and is reduced to random-choice levels at an average delay time of 8.68 +/- 0.06 sec. Second, when the DMTS task involves two samples (one relevant, the other irrelevant), bees can be trained to learn to use the relevant sample to perform the task if (i) the relevant sample is always at a fixed position, or (ii) the relevant sample always has the same place in the sequence of presentation (always first or always second). Bees that have learned to use the relevant sample and to ignore the irrelevant sample can generalize this learning, and apply it to novel sets of sample and comparison stimuli that they have never previously encountered. The findings point to a remarkably robust, and yet plastic, working memory in the honey bee.

Animals↗
PubMed2006

Perceptual-learning evidence for separate processing of asynchrony and order tasks.

Normal perception depends, in part, on accurate judgments of the temporal relationships between sensory events. Two such relative-timing skills are the ability to detect stimulus asynchrony and to discriminate stimulus order. Here we investigated the neural processes contributing to the performance of auditory asynchrony and order tasks in humans, using a perceptual-learning paradigm. In each of two parallel experiments, we tested listeners on a pretest and a posttest consisting of auditory relative-timing conditions. Between these two tests, we trained a subset of listeners approximately 1 h/d for 6-8 d on a single relative-timing condition. The trained listeners practiced asynchrony detection in one experiment and order discrimination in the other. Both groups were trained at sound onset with tones at 0.25 and 4.0 kHz. The remaining listeners in each experiment, who served as controls, did not receive multihour training during the 8-10 d between the pretest and posttest. These controls improved even without intervening training, adding to evidence that a single session of exposure to perceptual tasks can yield learning. Most importantly, each of the two groups of trained listeners learned more on their respective trained conditions than controls, but this learning occurred only on the two trained conditions. Neither group of trained listeners generalized their learning to the other task (order or asynchrony), an untrained temporal position (sound offset), or untrained frequency pairs. Thus, it appears that multihour training on relative-timing skills affects task-specific neural circuits that are tuned to a given temporal position and combination of stimulus components.

Acoustic Stimulation↗
PubMed1995

Why Johnny can't reengineer health care processes with information technology.

Many educational institutions are developing curricula that integrate computer and business knowledge and skills concerning a specific industry, such as banking or health care. We have developed a curriculum that emphasizes, equally, medical, computer, and business management concepts. Along the way we confronted a formidable obstacle, namely the domain specificity of the reference disciplines. Knowledge within each domain is sufficiently different from other domains that it reduces the leverage of building on preexisting knowledge and skills. We review this problem from the point of view of cognitive science (in particular, knowledge representation and machine learning) to suggest strategies for coping with incommensurate domain ontologies. These strategies include reflective judgment, implicit learning, abstraction, generalization, analogy, multiple inheritance, project-orientation, selectivity, goal- and failure-driven learning, and case- and story-based learning.

Commerce↗
PubMed1991

Peak shift revisited: a test of alternative interpretations.

In Experiment 1, 2 groups of human subjects were trained to respond to 1 of 2 light intensity stimuli, S2 or S4, and then were tested for generalization with a randomized series of increasing values from S1 to S11. Both groups, including the group trained to respond to dimmer value, showed peak shifts to a brighter more centrally located test stimulus. In Experiment 2, which used line angle stimuli, both the size of the difference between S+ and S- and the range of test stimuli that extended beyond S+ were varied. The larger the S(+)-S- separation and the larger the range, the greater was the peak shift obtained. In Experiment 3, training involved an S- (line angle) surrounded by 2 S+ values with testing symmetrical about the training values and covering either a narrow or a wide range. The wide range produced greater peak shifts in both directions from S-. All 3 experiments support an adaptation-level interpretation of intradimensional discrimination learning and generalization test performance in human subjects. Related work with animals suggests the presence of similar processes.

Adult↗
PubMed1999

Portfolios in continuing medical education--effective and efficient?

INTRODUCTION: A cross over comparison between 'traditional' continuing medical education (CME) activities and portfolio-based learning in general practice is described. METHOD: Thirty-two volunteer general practitioners (GPs) were divided into two cohorts; each cohort spent six months following a 'traditional' route to postgraduate educational accreditation (PGEA) and six months following a portfolio-based learning route supported by three CME tutors. OUTCOME MEASURES: These were the submission of a completed portfolio with evidence of the completion of learning cycles and participants reflections on the educational process. Qualitative and quantitative evaluation data were collected by questionnaire, semi-structured interview, participant observation and review of completed portfolios. RESULTS: The themes identified by GPs as hopes for the portfolios were largely fulfilled and the anxieties generally confounded. The flexibility of the portfolio learning process was particularly important to the participants. The breadth of topics covered by the portfolios was extremely wide and comparison with the submissions for 'traditional' PGEA showed a much smaller spread of learning activities and fewer subjects of study. EFFECTIVENESS: The use of the portfolios of critical incidents and the completion of learning cycles with application to practice provided evidence of the effectiveness of such learning. EFFICIENCY: The mean number of hours spent by GPs preparing the portfolios was 24.5 +/- 12 (SD) which was significantly more than the 15 hours of PGEA awarded. CONCLUSIONS: This study demonstrates that a portfolio-based learning scheme can meet the needs of GPs relevant to their professional practice; it can give learners control over how, what and when they learn and encourage active and peer-supported learning; it can build personal and professional confidence and be thought both valid and reliable by participants. Learning outcomes can also be reliably assessed by PGEA within the context of an individually created learning plan.

Cohort Studies↗
PubMed2005

Cocaine-induced conditioned taste avoidance over extended conditioned stimulus-unconditioned stimulus intervals.

Although long-delay learning has been demonstrated numerous times in the conditioned taste avoidance procedure, the empirical evidence showing this is almost exclusively limited to studies using emetics. Given that compounds outside the emetic class (e.g. drugs of abuse) are also effective in inducing conditioned taste avoidances, the present study assessed the ability of cocaine, a non-emetic psychoactive compound, to support long-delay conditioning as the unconditioned stimulus in conditioned taste avoidance preparation. Using saccharin as the conditioned stimulus, two taste-drug pairings were followed by six extinction trials during which saccharin was presented without subsequent injections of cocaine. During the two conditioning trials, animals were injected subcutaneously with cocaine (32 mg/kg) at different conditioned stimulus-unconditioned stimulus intervals, that is, 10, 60, 120, 180, 240, 300, 420 and 540 min. A control group of animals was given an equi-volume injection of the drug vehicle at the 10-min conditioned stimulus-unconditioned stimulus interval. After two conditioning trials, all treatment groups consumed significantly less saccharin than controls, with the magnitude of the effect decreasing as the conditioned stimulus-unconditioned stimulus interval increased. After six extinction trials, animals injected with cocaine at 10, 60 and 120 min conditioned stimulus-unconditioned stimulus intervals still consumed significantly less than controls. These results with cocaine suggest that taste avoidance learning over long delays is not limited to classical emetic compounds and may, in fact, be characteristic of taste avoidance learning in general.

Animals↗
PubMed2001

Annotation: the cognitive neuroscience of face recognition: implications for developmental disorders.

Face recognition is often considered to be a modular (encapsulated) function. This annotation supports the proposal that faces are special, but suggests that their identification makes use of general-purpose cortical systems that are implicated in high-level vision and also in memory and learning more generally. These systems can be considered to function within two distinct cortical streams: a medial stream (for learning and salience of faces encountered) and a lateral stream (for distributed representations of visual properties and identities of faces). Function in the lateral stream, especially, may be critically dependent on the normal development of magnocellular vision. The relevance of face recognition anomalies in three developmental syndromes (Autism, Williams syndrome, and Turner syndrome) and the two-route model sketched above is considered.

Autistic Disorder↗
PubMed2003

Development and evaluation of a computer-animated tutor for vocabulary and language learning in children with autism.

Using our theoretical framework of multimodal processing, we developed and evaluated a computer-animated tutor, Baldi, to teach vocabulary and grammar for children with autism. Baldi was implemented in a Language Wizard/Player, which allows easy creation and presentation of a language lesson involving the association of pictures and spoken words. The lesson plan includes both the identification of pictures and the production of spoken words. In Experiment 1, eight children were given initial assessment tests, tutorials, and reassessment tests 30 days following mastery of the vocabulary items. All of the students learned a significant number of new words and grammar. A second within-subject design with six children followed a multiple baseline design and documented that the program was responsible for the learning and generalization of new words. The research indicates that children with autism are capable of learning new language within an automated program centered around a computer-animated agent, multimedia, and active participation and can transfer and use the language in a natural, untrained environment.

Autistic Disorder↗
PubMed2006

Tikhonov training of the CMAC neural network.

The architecture of the cerebellar model articulation controller (CMAC) presents a rigid compromise between learning and generalization. In the presence of a sparse training dataset, this limitation manifestly causes overfitting, a drawback that is not overcome by current training algorithms. This paper proposes a novel training framework founded on the Tikhonov regularization, which relates to the minimization of the power of the sigma-order derivative. This smoothness criterion yields to an internal cell-interaction mechanism that increases the generalization beyond the degree hardcoded in the CMAC architecture while preserving the potential CMAC learning capabilities. The resulting training mechanism, which proves to be simple and computationally efficient, is deduced from a rigorous theoretical study. The performance of the new training framework is validated against comparative benchmarks from the DELVE environment.

Algorithms↗
PubMed1999

Bereavement and grief in adults with learning disabilities. A follow-up study.

BACKGROUND: This paper reports on the follow-up of a cohort of parentally bereaved adults with learning disabilities. AIMS: To investigate whether significant psychopathology, present up to 2.1 years after the death, had resolved five years later. METHOD: Of an original sample of 50 adults with learning disabilities, 41 were reassessed. The Aberrant Behaviour Checklist and the Psychopathology Instrument for Mentally Retarded Adults were re-administered to carers. RESULTS: At follow-up, there was a small increase in the measures of aberrant behaviour. Measures of psychopathology showed improvement, and in particular there was a reduction in anxiety. CONCLUSIONS: The response to bereavement by adults with learning disabilities is similar in type, though not in expression, to that of the general population. Learning disability is a significant predictor of mental health problems following bereavement. Participants adapted more easily when basic emotional needs had been constructively met by carers.

Adult↗
PubMed2001

A selective learning method to improve the generalization of multilayer feedforward neural networks.

Multilayer feedforward neural networks with backpropagation algorithm have been used successfully in many applications. However, the level of generalization is heavily dependent on the quality of the training data. That is, some of the training patterns can be redundant or irrelevant. It has been shown that with careful dynamic selection of training patterns, better generalization performance may be obtained. Nevertheless, generalization is carried out independently of the novel patterns to be approximated. In this paper, we present a learning method that automatically selects the training patterns more appropriate to the new sample to be predicted. This training method follows a lazy learning strategy, in the sense that it builds approximations centered around the novel sample. The proposed method has been applied to three different domains: two artificial approximation problems and a real time series prediction problem. Results have been compared to standard backpropagation using the complete training data set and the new method shows better generalization abilities.

Forecasting↗
PubMed1962

Instructions and stimulus categorizing in a measure of stimulus generalization.

In Experiment I, three groups of 20 Ss each were exposed to a light of 550 mmu (yellowish-green) for 60 sec and then viewed a random sequence of wavelengths with instructions to respond only to the original color. The instructions given the three groups were worded differently in an attempt to vary the strength of a set-to-discriminate assumed to be created by this procedure. The three groups produced similar gradients, each with a peak of responding at 540 mmu, in agreement with Kalish's (1958) published gradient for the 550 mmu standard stimulus value. It was suggested that the nature of the task is such that a strong discriminatory set is produced regardless of the wording of the instructions.A temporal analysis of the gradient as it develops during the testing revealed that initially the peak of responding occurs at 550 mmu; but as testing progresses, it shifts gradually in the direction of the shorter wavelengths (purer greens). Experiment II was performed to test the generality of the phenomenon of regression to the primary color. Two groups of 20 Ss each were tested for generalization following exposure to 510 mmu (bluish-green) and 525 mmu (pure green), respectively. We predicted that the 510 mmu gradient would reveal a progressive shift toward the longer wavelengths (purer greens), whereas the 525 mmu gradient would show no tendency to shift. The results were strikingly in accord with these predictions. We concluded that although a physiological process could not be ruled out, the verbal labeling of the standard stimulus value may well be responsible for the regression of the gradient toward the primary color.

Color↗
PubMed1985

Cellular mechanisms of learning, memory, and information storage.

In Table 1, we summarize what is convincingly demonstrated to date for the major vertebrate and invertebrate model systems attempting to elucidate cellular mechanisms of associative learning. Two major concerns are the adequacy of the behavioral demonstrations and the completeness and extent of the accompanying neurophysiology. In addressing the issue of behavior, it is important to define clearly which criteria are both necessary and sufficient to infer the involvement of an associative-learning process. Similarly, it is also important to distinguish among those primary characteristics of associative learning in general, and those secondary or tertiary features that serve to define various subclasses. In our view, it would be unreasonable to require that any given preparation exhibit all the defining features of classical conditioning, for example, in order to qualify as a "legitimate" instance of associative learning. This is especially true if the goal is to understand the more general, rather than the specific, mechanisms involved in associative learning. Hence, we emphasize the following as primary features of learned behavior: pairing specificity, stimulus specificity, long-term retention (arbitrarily defined as lasting for at least 24 hr), a moderate degree of reversibility by subsequent experience (e.g. extinction), and demonstrations that nonassociative-learning processes cannot account for features a-c. Where appropriate, we also identified other interesting features of the learned behavior. It is apparent from the table that a major unresolved issue for most of the preparations is the extent to which the behavioral changes are exclusively associative. This is no less true for the vertebrate preparations than it is for the invertebrates. The clearest example of an exclusively associative behavioral change is the rabbit NMR. The learning-produced changes in the invertebrate preparations were all shown, to varying degrees, to be pairing specific. Yet a major unresolved issue is the degree to which apparent examples of associative-learning reflect complex interactions among basically nonassociative-learning processes. The core issue is really quite simple: Does the associative training procedure result in the acquisition of new or qualitatively different behavior; and is there a strict requirement for an associative relation? In addressing the adequacy of the neurophysiological analyses, the major issue is that of localization. Logically, there are two components to this.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗