<p>Human learning and memory relies on a broad network of neural substrates, and is sensitive to a range of environmental factors and behaviors. The present studies are designed to investigate the modulation of active exploration behaviors in humans. In the current work, we operationalize exploration in two ways: participants’ spatial navigation (using a computer mouse) in environments containing rewarding and informative stimuli, and participants’ eyegaze activity while viewing images on a computer screen. The study described in Study 1 investigates the relationship between spatial exploration and reward, using participants’ reported anxiety levels to predict between-subject variability in vigor and information-seeking. The study described in Study 2 investigates the relationship between cue-outcome predictive validity and eyegaze behavior during learning; additionally, we test the extent to which differing states of expectation drive differences in eyegaze behavior to novel images. The study described in Study 3 expands on the questions raised in Study 2: using functional imaging and eyetracking, we investigate the relationship between predictive validity, gaze, and the neural systems supporting active exploration. Taken together, the findings in the present study suggest that emerging certainty in reward outcomes, rather than uncertainty, drives exploration and associative learning for events and their outcomes as well as encoding into long-term memory.</p> / Dissertation

Recent research has found that subjects learning a list of paired-associates under conditions requiring one-trial learning are capable of learning a list of paired items in as few a number of trials as subject learning similar lists of paired-associates under a condition using repetition.

Pour ces travaux de thèse, nous proposons pour la première fois une méthodologie systématique pour étudier les propriétés tactiles de tissu au travers de perceptions visuelles. Tout d’abord, nous étudions les bases physiologiques et cognitives des perceptions visuelles et haptiques des propriétés tactiles des tissus. Ensuite, une hypothèse fondamentale est proposée pour que les propriétés tactiles des tissus puissent être interprétées à travers nos yeux. Afin de vérifier cette hypothèse, des expériences sensorielles ont été conduites sur un nombre important de produits textiles selon trois différents scénarii : vidéo, image et toucher réel. Une nouvelle approche basée sur le concept de degré d’inclusion est développée pour étudier les relations entre les données tactiles obtenues à partir des différentes modalités sensorielles. De cette manière, nous concluons qu’il est tout à fait possible de percevoir les propriétés tactiles des tissus à travers des représentations visuelles. Ceci confirme l’hypothèse proposée précédemment. En nous appuyant sur ces résultats, afin d’explorer le mécanisme interprétatif de la vision, nous effectuons de nouvelles expériences sensorielles, permettant d’évaluer respectivement les caractéristiques visuelles et les propriétés tactiles des échantillons. Ensuite, nous modifions l’approche mathématique proposée précédemment afin de mesurer les relations de type un à plusieurs, de manière à extraire pour chaque propriété tactile d’un ensemble de caractéristiques visuelles les plus pertinentes. Enfin, ANFIS (un réseau neuronal combinant les techniques floues) est utilisé pour modéliser et interpréter quantitativement ces relations. / In the current thesis, we propose for the first time a systematic methodology to study fabric tactile properties through visual perceptions. First of all, we investigate the physiological and cognitive basis of visual and haptic perceptions of fabric tactile properties. Next, we propose a fundamental hypothesis that fabric tactile properties can be, to a big extent, interpreted through our eyes. In order to verify this hypothesis, sensory experiments are carried out on a number of textile products in video, image and real-touch scenarios. A novel approach based on the concept of inclusion degree is developed to study the relations between the tactile data obtained from different sensory modalities. From this study, we conclude that it is possible to perceive fabric tactile properties through visual representations, which confirms the previously proposed hypothesis. On this basis, in order to further explore the visual interpretative mechanism, new sensory experiments are organized to evaluate samples’ visual features and tactile properties, respectively. The previously proposed mathematical approach is modified to be able to measure multiple-to-single relations so as to extract for each tactile property a set of relevant visual features on it. Finally, a fuzzy neural network (Adaptive network-based fuzzy inference system, in short ANFIS) is developed to model the obtained interpretative relationships.

Han-bing Ji. / Thesis (Ph.D.)--Chinese University of Hong Kong, 1996. / Includes bibliographical references (p. 160-163). / Microfiche. Ann Arbor, Mich.: UMI, 1998. 2 microfiches ; 11 x 15 cm.

We determine several families of so-called associative 3-dimensional manifolds in R7. Such manifolds are of interest because associative 3-cycles in G2 holonomy manifolds such as R6 × S1, whose universal cover is R7, are candidates for representations of fundamental particles in String Theory. We apply the classic results of Harvey and Lawson to find 3-manifolds which are graphs of functions f : Im H → H and which are invariant under a particular 1-parameter subgroup of G2, the automorphism group of the Cayley numbers, O. Systems of PDEs are derived and solved, some special cases of a classic theorem of Harvey and Lawson are investigated, and theorems aiding in the classification of all such manifolds described here are proven. It is found that in most of the cases examined, the resulting manifold must be of the form of the graph of a holomorphic function crossed with R. However, some examples of other types of graphs are also found.

We review some computational aspects of motor control. The problem of trajectory control is phrased in terms of an efficient representation of the operator connecting joint angles to joint torques. Efficient look-up table solutions of the inverse dynamics are related to some results on the decomposition of function of many variables. In a biological perspective, we emphasize the importance of the constraints coming from the properties of the biological hardware for determining the solution to the inverse dynamic problem.

No description available.

Increased impulsivity and alterations in reward sensitivity co-occur in many psychiatric disorders. Moreover, individuals reporting more impulsive traits are less efficient in learning stimulus-reward associations. This suggests that impulsivity and reward sensitivity may be linked, consistent with evidence that the orbital frontal cortex (OFC) is implicated in both processes. This study examined the relationship between impulsive traits, assessed by the Barratt Impulsiveness Scale (BIS) and the Eysenck (EIQ), and performance on three behavioral tasks that measure impulsivity and reward sensitivity. The tasks included a Conditioned Pattern Preference (CPP) task, which measures the preference for abstract visual cues as an index of implicit emotional learning, a Probabilistic Reversal Learning (PRL) task that assessed the ability to alter behaviour when reward contingencies change and an Emotional Stroop task which assessed attentional control in response to emotionally salient stimuli. This study provided novel information on the relationship between processes that mediate impulsivity and reward sensitivity. In brief, subjects that were considered to have some explicit knowledge of experimental conditions showed a higher preference formation for the pattern paired with the reward on 90% of the conditioning trials. Although there was no overall effect of impulsivity, the medium impulsive group displayed the strongest preference formation (highest score for the 90% pattern and lowest score for the 10% pattern) compared to the low and high groups. Furthermore, there was an overall effect of Word Category in that participants made more errors for the emotional words (positive and negative) than the neutral words. There was no overall effect of Impulsivity on Stroop performance in this sample. Finally, for the PRL task more participants in the high impulsive group did not meet criterion for the Acquisition stage while more low impulsive subjects did not meet reversal criterion. Furthermore, high impulsive subjects made more overall errors in the Acquisition stage but not Reversal stage. In brief, low and high impulsive subjects performed sub-optimally on the CPP and PRL tasks but not on the Stroop task. This pattern reflects an inverted-U shaped relationship of the effects of impulsivity on associative learning. / Thesis (Master, Psychology) -- Queen's University, 2010-02-05 13:33:27.076

Thesis (Ph. D.)--University of Hong Kong, 2008. / Includes bibliographical references (leaf 31-35) Also available in print.

Thesis (MSc)--University of Stellenbosch, 2005. / Bibliography. Also available via the Internet.