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At least 343 records · Page 19Linked to original sources
PubMed2004

Stimulus generalization in two associative learning processes.

Recent studies involving nonlinear discrimination problems suggest that stimuli in human associative learning are represented configurally with narrow generalization, such that presentation of stimuli that are even slightly dissimilar to stored configurations weakly activate these configurations. The authors note that another well-known set of findings in human associative learning, cue-interaction phenomena, suggest relatively broad generalization. Three experiments show that current models of human associative learning, which try to model both nonlinear discrimination and cue interaction as the result of 1 process, fail because they cannot simultaneously account for narrow and broad generalization. Results suggest that human associative learning involves (a) an exemplar-based process with configural stimulus representation and narrow generalization and (b) an adaptive learning process characterized by broad generalization and cue interaction.

Cues↗
PubMed2002

Associative learning and elemental representation: II. Generalization and discrimination.

This paper follows on from an earlier companion paper (McLaren & Mackintosh, 2000), in which we further developed the elemental associative theory put forward in McLaren, Kaye, and Mackintosh (1989). Here, we begin by explicating the idea that stimuli can be represented as patterns of activation distributed across a set of units and that different stimuli activate partially overlapping sets (the degree of overlap being proportional to the similarity of the stimuli). A consequence of this view is that the overall level of activity of some of the units representing a stimulus may be dependent on the nature of the other stimuli present at the same time. This allows an elemental analysis in which provision for the representation of configurations of stimuli is made. A selective review of studies of generalization and discrimination learning, including peak shift, transfer along a continuum, configural discrimination, and summation, suggests that the principles embodied in this class of theory deserve careful consideration and will form part of any successful model of associative learning in humans or animals. There are some phenomena that require an elemental/associative explanation.

Association Learning↗
PubMed2003

Generalized Kohonen's competitive learning algorithms for ophthalmological MR image segmentation.

Kohonen's self-organizing map is a two-layer feedforward competitive learning network. It has been used as a competitive learning clustering algorithm. In this paper, we generalize Kohonen's competitive learning (KCL) algorithm with fuzzy and fuzzy-soft types called fuzzy KCL (FKCL) and fuzzy-soft KCL (FSKCL). These generalized KCL algorithms fuse the competitive learning with soft competition and fuzzy c-means (FCM) membership functions. We then apply these generalized KCLs to MRI and MRA ophthalmological segmentations. These KCL-based MRI segmentation techniques are useful in reducing medical image noise effects using a learning mechanism. They may be particularly helpful in clinical diagnosis. Two real cases with MR image data recommended by an ophthalmologist are examined. First case is a patient with Retinoblastoma in her left eye, an inborn malignant neoplasm of the retina frequently metastasis beyond the lacrimal cribrosa. The second case is a patient with complete left side oculomotor palsy immediately after a motor vehicle accident. Her brain MRI with MRA, skull routine, orbital CT, and cerebral angiography did not reveal brainstem lesions, skull fractures, or vascular anomalies. These generalized KCL algorithms were used in segmenting the ophthalmological MRIs. KCL, FKCL and FSKCL comparisons are made. Overall, the FSKCL algorithm is recommended for use in MR image segmentation as an aid to small lesion diagnosis.

Algorithms↗
PubMed2005

Heuristics and general principles of learning.

This research on decision-making heuristics is similar to research on animal learning in at least two ways. First, optimality modeling has not proven to be very useful for either research area. Second, both of these research areas seek to find general principles (or heuristics) that are applicable to different species in different settings. However, the basic principles of classical and operant conditioning seem to be more uniform across species and situations, whereas decision-making heuristics can vary for different species and different situations, even for tasks with very similar characteristics.

Algorithms↗
PubMed1993

Continuing education for general practice. 2. Systematic learning from experience.

Prompted by evidence that the recently-adopted arrangements for ongoing education among established general practitioners are unsatisfactory, the first of a pair of papers examined the theoretical basis of continuing education for general practice and proposed a model of self-directed learning in which the experience of established practitioners is connected, through the media of reading, reflection and audit, with competence for the role. In this paper a practical, systematic approach to self-directed learning by general practitioners is described based on the model. The contribution which appropriate participation in continuing medical education can make to enhancing learning from experience is outlined.

Behavior↗
PubMed2006

Generalized manifold-ranking-based image retrieval.

In this paper, we propose a general transductive learning framework named generalized manifold-ranking-based image retrieval (gMRBIR) for image retrieval. Comparing with an existing transductive learning method named MRBIR [12], our method could work well whether or not the query image is in the database; thus, it is more applicable for real applications. Given a query image, gMRBIR first initializes a pseudo seed vector based on neighborhood relationship and then spread its scores via manifold ranking to all the unlabeled images in the database. Furthermore, in gMRBIR, we also make use of relevance feedback and active learning to refine the retrieval result so that it converges to the query concept as fast as possible. Systematic experiments on a general-purpose image database consisting of 5,000 Corel images demonstrate the superiority of gMRBIR over state-of-the-art techniques.

Algorithms↗
PubMed2006

Summation in causal learning: elemental processing or configural generalization?

Results from human causal learning tasks that employ multiple cues are often interpreted in terms of the elemental theory of Rescorla and Wagner (1972). However, most results can also be successfully interpreted by the configural model proposed by Pearce (1987, 1994). One method of discriminating between these alternatives is through an investigation of summation and overexpectation. Indeed, demonstrations of these phenomena are fundamental to an elemental approach but are generally incompatible with an account that involves configural processing. Using a procedure in which the magnitude of the outcome varied, evidence for both summation and overexpectation was obtained in two experiments.

Adolescent↗
PubMedDate not supplied

Interpretive management: what general managers can learn from design.

The past two decades have seen a dramatic acceleration in the pace of marketplace change. Companies have abandoned the old hierarchical model, with its clean functional divisions and clear lines of authority, and adopted flatter, less bureaucratic structures. But if most organizations have begun to adapt to the uncertainty of rapid change, most managers have not. They remain locked into the mechanical mind-set of the industrial age--that is, they assume that any management challenge can be translated into a clearly defined problem for which an optimal solution can be found. That approach works in stable markets and even in markets that change in predictable ways. Today's markets, however, are increasingly unstable and unpredictable. Managers can never know precisely what they're trying to achieve or how best to achieve it. They can't even define the problem, much less engineer a solution. The challenges facing the general manager in these circumstances, the authors argue, resemble those typically confronted by design managers. In the unpredictable world of research and design, neither the flow of the development process nor its end point can be defined at the outset. Rather than the traditional analytical approach to management, the design world requires an interpretive one. And that approach is equally well suited to rapidly changing, unpredictable markets. The authors describe how companies such as Levi Strauss & Company and Chiron Corporation have stayed at the top of their industries by adopting just such an interpretive approach to management.

Administrative Personnel↗
PubMed1999

Optimal chaos control through reinforcement learning.

A general purpose chaos control algorithm based on reinforcement learning is introduced and applied to the stabilization of unstable periodic orbits in various chaotic systems and to the targeting problem. The algorithm does not require any information about the dynamical system nor about the location of periodic orbits. Numerical tests demonstrate good and fast performance under noisy and nonstationary conditions. (c) 1999 American Institute of Physics.

Journal Article↗
PubMed1989

Appetitive learning in snails shows characteristics of conditioning in vertebrates.

The snail Lymnaea stagnalis can be rapidly conditioned to produce feeding response to a previously neutral tactile stimulus, repeatedly and specifically paired with positive reinforcement (food). The conditioned response has many of the same characteristics seen in appetitive learning in vertebrates. The relative simplicity of the molluscan CNS and the detailed knowledge of the neural circuitry underlying feeding in Lymnaea will facilitate the neurophysiological analysis of appetitive learning as well as stimulus generalization, discriminative learning and generalization of extinction all described in the present paper.

Animals↗
PubMed2005

Decisions, decisions: infant language learning when multiple generalizations are possible.

Two experiments presented infants with artificial language input in which at least two generalizations were logically possible. The results demonstrate that infants made one of the two generalizations tested, the one that was most statistically consistent with the particular subset of the data they received. The experiments shed light on how learners might go about solving the induction problem for human language.

Analysis of Variance↗
PubMed2006

Category-specific organization of prefrontal response-facilitation during priming.

Perceptual priming is a fundamental long-term memory capability that allows more efficient and faster responding to a stimulus as a result of prior exposure to that stimulus. The two major components of priming are facilitated response expression and improved stimulus identification. Recent fMRI studies have identified a potential neural correlate for response-facilitation, namely the repetition-related activity decrements in prefrontal cortex that are linearly correlated with improvements in reaction times. However, the neural processes underlying such response-facilitation are still unclear. They could be stimulus-selective stimulus-response mapping processes or general response-learning mechanisms. In human imaging studies, behavioral priming has been associated with decreased hemodynamic responses in prefrontal cortex and in category-specific brain regions of the ventral visual stream. Currently, it is unclear whether priming-related response decreases in prefrontal cortex are also category-specific. In this fMRI study, 16 subjects performed a repetition priming task employing category-specific identification judgments on pictures of faces (male/female judgment), scenes (indoor/outdoor judgment) and scrambled 'noise' pictures (simple button press). The repeated faces and scenes were identified faster than first presentations indicating priming. Hemodynamic decreases for repetitions were observed in a left inferior (near Brodman Area, BA, 44) and middle frontal (BA8) region of the prefrontal cortex, in category-specific areas of the ventral stream (bilateral fusiform face area, FFA, parahippocampal place area, PPA), and two category-specific right lateral occipital (LOC) regions. Hemodynamic increases for repetitions appeared in the caudate and cerebellum. However, the prefrontal areas were the only regions that showed a correlation between repetition-related reaction time improvement and hemodynamic decrease. Importantly, the correlations were category-specific in their relationship to reaction time improvement: in the left inferior frontal cortex the correlations were specific for scenes whereas and in left middle frontal gyrus they were specific for faces. There were no correlations between behavior and repetition suppression for both LOC regions, FFA and PPA. These data reveal that response-facilitation in prefrontal cortex is organized according to stimulus-properties, compatible with learning of stimulus-response mapping rather than response learning in general.

Adult↗