Made available in DSpace on 2016-06-02T20:30:50Z (GMT). No. of bitstreams: 1 3021.pdf: 1554861 bytes, checksum: 79bd6fbda8332922bee3c9d6c05f7a59 (MD5) Previous issue date: 2010-03-08 / Universidade Federal de Minas Gerais / The paradigm of stimulus equivalence has been widely studied, with different populations. Several studies have investigated the variables that can influence the formation and maintenance of equivalent stimulus classes. Regarding to formation, some authors point that the structure of train CaN and the arrangement simple to complex can facilitate this formation. Regarding to maintenance, some authors propose, for example, that classes with higher number of stimuli are more stable and are easier to be remembered over time. Despite the diversity of populations studied with procedures derived from the paradigm of stimulus equivalence, there is still a lack of studies with the elderly population. In order to enlarge the knowledge about the generality of the phenomenon of formation and maintenance of equivalent classes stimulus, this study proposed to investigate the formation of equivalent classes of different sizes and the role of this size in the maintenance of the classes with participants between 60 and 75 years. The procedure of matching-to-sample was used to teach three classes of equivalent stimuli composed of three or six stimulus (Condition 1 and Condition 2). The experimental procedure consisted of a training phase of baseline relations and testing of emerging relations, and six weeks after the first phase, a test was done with the emerging and learned relations to check the maintenance of classes formed. All participants showed the emergence of classes of equivalent stimulus. Three participants showed immediate emergency and five delayed emergency. All the participants who went through Condition 1 had percentages of correct responses below 90% in the test done after six weeks, while participants who underwent Condition 2 had hit percentages above 90%. Since most participants from Condition 2 showed accuracy right in the beginning of the test, it was not possible to evaluate the recovery of the relations throughout the test made six weeks later. This performance showed that the size of the class may be a relevant variant that influences the stability of the class over time, since the participants in the condition that trained with larger classes had better results on this test. This paper presents contributions to the studies of stimulus equivalence, since studies with this population are rare, and to understanding the factors involved in the formation and maintenance of stimulus equivalence. / O paradigma da equivalência de estímulos tem sido amplamente estudado, com diferentes populações. Diversas pesquisas têm investigado as variáveis que podem influenciar na formação e na manutenção de classes de estímulos equivalentes. Em relação à formação, autores apontam que a estrutura de treino CaN e o arranjo do simples para o complexo podem facilitar essa formação. Em relação à manutenção, autores propõem, por exemplo, que classes com maior número de estímulos são mais estáveis ao longo do tempo e são recuperadas mais facilmente. Apesar da diversidade de populações estudadas com procedimentos oriundos do paradigma de equivalência de estímulos, existe ainda uma carência de estudos com a população idosa. Com o objetivo de ampliar o conhecimento sobre a generalidade do fenômeno de formação e manutenção de classes de estímulos equivalentes, o presente estudo propôs verificar a formação de classes de estímulos equivalentes de diferentes tamanhos e o papel deste tamanho na manutenção das mesmas com participantes idosos entre 60 e 75 anos. O procedimento de emparelhamento com o modelo foi utilizado para ensinar três classes de estímulos equivalentes compostas por três ou seis estímulos (Condição 1 e Condição 2). O procedimento experimental consistiu em uma fase de treino de relações de linha de base e teste de relações emergentes seguida, seis semanas depois, de um teste com as relações aprendidas e emergentes a fim de verificar a manutenção das classes formadas. Todos os participantes mostraram a emergência de classes de equivalência. Três participantes mostraram emergência imediata e cinco, emergência atrasada. Em geral, os participantes que passaram pela Condição 1 apresentaram porcentagens de acertos abaixo de 90% no teste feito após seis semanas, enquanto os participantes que passaram pela Condição 2 apresentaram porcentagens de acerto acima de 90%. Uma vez que a maior parte dos participantes da Condição 2 apresentaram porcentagens de acertos muito altas desde o inicio do teste, não foi possível avaliar a recuperação das relações ao longo do teste feito após seis semanas. Esse desempenho evidenciou que o número de estímulos em um classe pode ser uma variável que influencia na estabilidade das classes ao longo do tempo, uma vez que os participantes da condição que treinaram com classes maiores tiveram resultados melhores neste teste. O trabalho apresenta contribuições para os estudos em equivalência de estímulos, uma vez que estudos com população dessa idade são escassos, para a compreensão dos fatores envolvidos na formação e manutenção das classes de estímulos equivalentes.

No / Auditory signals have been shown to exert a marked influence on visual perception in a wide range of tasks. However, the mechanisms of these interactions are, at present, poorly understood. Here we present a series of experiments where a temporal cue within the auditory domain can significantly affect the localisation of a moving visual target. To investigate the mechanism of this interaction, we first modulated the spatial positional uncertainty of the visual target by varying its size. When visual positional uncertainty was low (small target size), auditory signals had little or no influence on perceived visual location. However, with increasing visual uncertainty (larger target sizes), auditory signals exerted a significantly greater influence on perceived visual location. We then altered the temporal profile of the auditory signal by modulating the spread of its Gaussian temporal envelope. Introducing this temporal uncertainty to the auditory signal greatly reduced its effect on visual localisation judgements. These findings support the view that the relative uncertainty in individual sensory domains governs the perceptual outcome of multisensory integration.

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Thesis (PhD)-- Stellenbosch University, 1924. / ENGLISH ABSTRACT: No abstract available / AFRIKAANSE OPSOMMING: Sien artikel vir opsomming

In the present study, footshock, which produces a powerful aversive emotional response was used in a Pavlovian conditioning experiment as an unconditioned stimulis (UCS), and was paired with the presentation of a light used as a conditioned stimulis (CS). There is an accumulation of evidence that supports the assertion that dopaminergic (DA) neurons within the ventral tegmental area (VTA) are active in processes that contribute to the amygdala-based circuitry involved in regulating emotionally salient responses. To build upon findings implicating VTA DA, excitatory glutamate (Glu), NMDA and AMPA receptors, were examined with respect to their role in Pavlovian conditioned fear responding. Fear potentiated startle (FPS) was used to assess the effects of intra-VTA infused AP5, and intra-VTA infused CNQX on conditioned fear responding in laboratory rats. The administration of the NMDA receptor antagonist AP5 (at 1.0, 2.5, and 5.0ug doses), blocked the ability of a conditioned stimulus (CS) previously paired with footshock to become conditioned to the UCS. Similarly, administration of the AMPA receptor antagonist CNQX (at 1.0, 2.5, 5.0ug doses), inhibited the ability of the CS to become conditioned to the UCS. The results of this study indicate the VTA is an important site for synaptic modifications associated with fear learning, and that activation of excitatory Glutamatergic receptors in the VTA play a necessary part of the processing underlying fear conditioning. Measures of shock reactivity demonstrated that the infusion of AP5 and CNQX into the VTA did not inhibit baseline startle amplitudes. The administration of AP5 and CNQX did not suppress the perception of footshock as an aversive stimulus. This study provides further definition to established knowledge surrounding the neural processes whereby neutral environmental cues gain negative emotional salience as occurs in fear conditioning. It was hypothesised that the action of excitatory glutamatergic transmission within the VTA acts on NMDA and AMPA receptors is to assist in the acquisition of Pavlovian conditioned fear, possibly through the same synaptic mechanisms that govern LTP.

Several studies have demonstrated that fixed-time (FT) schedules of stimulus delivery can function to reduce a variety of behaviors. The purpose of this study was to evaluate the immediate and subsequent effects of FT food deliveries on mouthing. In Phase 1, a preference assessment showed that caramel popcorn, chocolate cookies and pretzels were highly preferred food items. Thus, providing the basis for use of food items during treatment. In Phase 2, a functional analysis showed that mouthing was a nonsocially maintained problem behavior. Phase 3 demonstrated the use of FT schedules of food deliveries as treatment for nonsocially maintained mouthing. Results indicated that FT schedules of food significantly reduced mouthing. In addition, levels of mouthing observed during post-FT observations were reliably lower than pre-FT observations. Treatment effects, operative mechanisms responsible for the treatment effects and the experimental arrangement used to investigate varying FT schedules are discussed.

A functional analysis, conducted to assess the variables maintaining the chronic eye poking of a female diagnosed with profound mental retardation, indicated that the behavior persisted in the absence of social contingencies. A procedure was initiated in a training environment in which a punisher (mild reprimand) was delivered contingent on eye poking in the presence, but not in the absence, of a neutral stimulus (wristbands). Using a combination of multiple baseline and multielement experimental designs, it was determined that that eye poking was suppressed in the presence of the previously neutral stimulus, even in environments in which the reprimand contingency was inoperative.

No description available.

This study partially replicated the research of Cook, Kwak, Hoffman, & Loftus where they examined post-event activities that induces subjects to pick a wrong person in a forced choice identification procedure. The goal was to investigate if providing a neither option to a match to sample task increases the accuracy of responding. Subjects were asked to study three faces for 10 seconds, after which they were asked to pick out the faces in a forced choice setting where two other faces were presented. Later the subjects were asked to pick out faces in a setting in which they could use a neither option. Results indicated that a generalization effect occurs when identifying faces and the effect is seen as subjects choosing the wrong face. This suggests that when using faces with some similar features in a lineup setting the procedure may cause the subject to pick the wrong person.

One language intervention approach for individuals with autism involves teaching one response topography under multiple sources of control and then establishing that response under individual controlling variable. Another approach involves establishing one response topography under singular control and then using that response to establish the response topography under different controlling variables. The study sought to extend previous research by investigating the impact of each approach on the acquisition of verbal responses. Three of the eight participants acquired all target responses for at least one response topography. The results of previous research were not replicated directly and the findings were discussed in terms of preexperimental verbal repertoires and restricted interests.