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Punching Strength of Flat Slabs with Unbraced Shear Reinforcement

Trautwein, Leandro Mouta; Bittencourt, Tulio Nogueira; Gomes, Ronaldo Barros; Bella, Joao Carlos Della
Fonte: AMER CONCRETE INST Publicador: AMER CONCRETE INST
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.87%
This paper analyzes the punching strength of concrete flat slabs with shear reinforcement that does not embrace flexural reinforcement. This paper also reports the results of tests of slabs without shear reinforcement. Finally, this paper shows some comparisons of tests of similar slabs without shear reinforcement and slabs with different types of shear reinforcement. The obtained results show that the use of shear reinforcement elements without embracement in the flexural reinforcement improves the punching strength of reinforced concrete flat slabs.; Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)

Influence of the reinforcement magnitude on omission effects

JUDICE-DAHER, Danielle Marcilio; TAVARES, Tatiane Ferreira; BUENO, Jose Lino Oliveira
Fonte: ELSEVIER SCIENCE BV Publicador: ELSEVIER SCIENCE BV
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.91%
Reinforcement Omission Effects (ROEs), indicated by higher rate of responses after nonreinforced trials in a partial reinforcement schedule, have been interpreted as behavioral transient facilitation after nonreinforcement induced by primary frustration, and/or behavioral transient inhibition after reinforcement induced by demotivation or temporal control. The size of the ROEs should depend directly on the reinforcement magnitude. The present experiment aimed to clarify the relationship between reinforcement magnitude and the omission effects manipulating the magnitude linked to discriminative stimuli in a partial reinforcement FI schedule. The results showed that response rates were higher after omission than after reinforcement delivery. Besides, response rates were highest immediately after the reinforcement omission of a larger magnitude than of a smaller magnitude. These data are interpreted in terms of ROEs multiple process behavioral facilitation after nonreinforcement, and behavioral transient inhibition after reinforcement. (C) 2011 Elsevier B.V. All rights reserved.; National Counsel for Technological and Scientific Development (CNPq, Brazil); Coordination for Improvement of Higher-Education Personnel (CAPES, Brazil); CNPq...

Involvement of the basolateral complex and central nucleus of amygdala in the omission effects of different magnitudes of reinforcement

Judice-Daher, Danielle M.; Tavares, Tatiane Ferreira; Bueno, Jose Lino Oliveira
Fonte: ELSEVIER SCIENCE BV; AMSTERDAM Publicador: ELSEVIER SCIENCE BV; AMSTERDAM
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.94%
Evidence from appetitive Pavlovian and instrumental conditioning studies suggest that the amygdala is involved in modulation of responses correlated with motivational states, and therefore, to the modulation of processes probably underlying reinforcement omission effects. The present study aimed to clarify whether or not the mechanisms related to reinforcement omission effects of different magnitudes depend on basolateral complex and central nucleus of amygdala. Rats were trained on a fixed-interval 12 s with limited hold 6 s signaled schedule in which correct responses were always followed by one of two reinforcement magnitudes. Bilateral lesions of the basolateral complex and central nucleus were made after acquisition of stable performance. After postoperative recovery, the training was changed from 100% to 50% reinforcement schedules. The results showed that lesions of the basolateral complex and central nucleus did not eliminate or reduce, but interfere with reinforcement omission effects. The response from rats of both the basolateral complex and central nucleus lesioned group was higher relative to that of the rats of their respective sham-lesioned groups after reinforcement omission. Thus, the lesioned rats were more sensitive to the omission effect. Moreover...

A natureza do reforçador como uma variável moduladora dos efeitos da história de reforço sobre o comportamento de seres humanos ; The nature of reinforcer as a modulating variable of effects of history of reinforcement on the human behavior

Costa, Carlos Eduardo
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 26/11/2004 PT
Relevância na Pesquisa
36.97%
O objetivo foi investigar como a natureza do reforçador afeta o comportamento humano em FI após diferentes histórias de reforço. Universitários foram expostos inicialmente a um de três programas de reforço: FR 40, DRL 20 s ou FI 10 s por três sessões de 15 minutos cada. As contingências de reforço foram programadas com o software ProgRef e a conseqüência para a resposta de pressionar um botão era pontos. Para alguns participantes os pontos eram trocados por fotocópias (Condição 1), para outros os pontos eram trocados por dinheiro (Condição 2), enquanto para outros os pontos não eram trocados por nada (Condição 3). Subseqüentemente, os participantes com história de FR e DRL foram expostos a um programa de reforço em FI 10 s e os participantes submetidos inicialmente ao FI 10 s tiveram o parâmetro do FI alterado para 5, 20 ou 30 s, por três sessões de 15 minutos cada. Os participantes da Condição 3-Pontos, expostos a histórias de responder em FR ou DRL, foram submetidos a cinco sessões de Extinção após as sessões de FI. Os participantes expostos ao FR apresentaram um padrão de responder em taxa alta e constante independentemente do tipo de reforçador utilizado. Quando a contingência mudou de FR para FI a taxa de respostas permaneceu alta para os participantes das Condições 1-Fotocópia e Condição 2-Dinheiro...

Variabilidade induzida e operante sob contingências de reforçamento negativo; Induced and operant variability under negative reinforcement contingences

Cassado, Desirée da Cruz
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 17/08/2009 PT
Relevância na Pesquisa
36.87%
A variabilidade comportamental pode ser induzida por reforçamento parcial ou extinção, assim como pode ser reforçada diferencialmente. O objetivo deste estudo foi verificar como a variabilidade comportamental pode ser influenciada por estímulos aversivos, tanto no processo de indução por reforçamento parcial e extinção, como no reforçamento negativo contingente à variação. Oito ratos Wistar machos foram divididos em dois experimentos. Em ambos foram realizadas sessões com 60 choques elétricos de (1mA), administrados no piso da caixa, em VT 60s (10-110s). O objetivo do Experimento 1 foi comparar os níveis de variabilidade da alocação da resposta de focinhar de três sujeitos experimentais em condições de nível operante, reforçamento negativo (fuga) e extinção. No Experimento 2 visou reforçar negativamente a variabilidade comportamental, expondo cinco sujeitos à sessões de Nível Operante, CRF, FR2, LAG1, LAG3 e Acoplado. Os resultados do Experimento 1 demonstram que os sujeitos emitiram a resposta de fuga durante as sessões de CRF com altos índices de variabilidade, mesmo a variabilidade não sendo exigida. Na sessão de extinção, dois dos sujeitos aumentaram ainda mais a variação das respostas. Discute-se que a resposta de focinhar ficou sob controle da contingência operante...

Aspectos adaptativos da variabilidade comportamental operante em um procedimento de omissão de reforço; Adaptive aspects of operant behavioral variability on a reinforcement omission procedure

Caldeira, Karine Marques
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 14/08/2014 PT
Relevância na Pesquisa
36.99%
Trabalhos recentes têm investigado como diferentes manipulações nas contingências de reforçamento podem afetar a variabilidade de respostas. Uma possível manipulação na liberação do reforço é a omissão de um reforço esperado. O objetivo do Experimento 1 foi investigar se a omissão do reforço pode afetar o comportamento de organismos reforçados por apresentar repetição ou diferentes níveis de variação de respostas operantes. Foram utilizados 32 ratos machos adultos Wistar. Foi realizado um treino de variabilidade e repetição operantes e a resposta considerada foi uma sequência de quatro pressões a qualquer de duas barras. Durante essa condição, os animais que passaram pelo treino de variabilidade foram reforçados de acordo com o esquema dependente da frequência. Havia um grupo com alta exigência de variação, um grupo com baixa exigência de variação e um grupo com exigência intermediária de variação para a liberação do reforço. Um quarto grupo foi reforçado continuamente por repetir a sequência DEEE e um quinto grupo recebeu os reforços de acordo com a distribuição dos reforços dos sujeitos do grupo de alta variabilidade, mas sem que precisassem variar suas respostas para isso. Após atingir um responder estável na condição de treino...

Efeitos de diferentes contingências de reforço no estabelecimento de discriminações condicionais e na formação de classes de estímulos equivalentes; Effect of different reinforcement contingencies on conditional discrimination acquisition and equivalence class formation

Soares Filho, Paulo Sergio Dillon
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 15/10/2014 PT
Relevância na Pesquisa
36.94%
As classes de equivalência de estímulos são produto das contingências de reforço. No entanto, as pesquisas têm utilizado apenas contingências de reforço positivo e investigado, na sua maioria, como eventos relacionados a um mesmo reforçador podem passar a compor uma mesma classe. O objetivo do presente trabalho foi avaliar o efeito de diferentes contingências de reforço, positivo e negativo, no estabelecimento de discriminações condicionais na formação de classes de equivalência em humanos. Foram realizados dois experimentos. No Experimento I, 12 participantes treinaram simultaneamente 12 relações condicionais (AB e BC) utilizando três arranjos de contingência de reforçamento diferentes: reforçamento positivo (Ganhar/Manter), reforçamento negativo (Manter/Perder) e uma contingência mista de reforçamento negativo e positivo (Ganhar/Perder), seguidos de testes de formação de classes de equivalência. No Experimento I, os participantes expostos aos testes de equivalência acertaram todas as tentativas de teste. Estes resultados demonstram a possibilidade de formação de classes de equivalência em uma contingência de reforço negativo, porém um possível efeito de teto impede a comparação de cada contingência na formação de classes. No Experimento II...

Using Reinforcement Learning in the tuning of Central Pattern Generators

Duarte, Ana Filipa de Sampaio Calçada
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Dissertação de Mestrado
Publicado em 12/12/2012 ENG
Relevância na Pesquisa
36.91%
Dissertação de mestrado em Engenharia Informática; É objetivo deste trabalho aplicar técnicas de Reinforcement Learning em tarefas de aprendizagem e locomoção de robôs. Reinforcement Learning é uma técnica de aprendizagem útil no que diz respeito à locomoção de robôs, devido à ênfase que dá à interação direta entre o agente e o meio ambiente, e ao facto de não exigir supervisão ou modelos completos, ao contrário do que acontece nas abordagens clássicas. O objetivo desta técnica consiste na decisão das ações a tomar, de forma a maximizar uma recompensa cumulativa, tendo em conta o facto de que as decisões podem afetar não só as recompensas imediatas, como também as futuras. Neste trabalho será apresentada a estrutura e funcionamento do Reinforcement Learning e a sua aplicação em Central Pattern Generators, com o objetivo de gerar locomoção adaptativa otimizada. De forma a investigar e identificar os pontos fortes e capacidades do Reinforcement Learning, e para demonstrar de uma forma simples este tipo de algoritmos, foram implementados dois casos de estudo baseados no estado da arte. No que diz respeito ao objetivo principal desta tese, duas soluções diferentes foram abordadas: uma primeira baseada em métodos Natural-Actor Critic...

Reinforcement contribution to the behavior of low-rise concrete walls

Carrillo,Julian; Guzmán,Andrés; Jerez,Sandra
Fonte: Associação Brasileira de Ciências Mecânicas Publicador: Associação Brasileira de Ciências Mecânicas
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2014 EN
Relevância na Pesquisa
36.84%
Based on steel strains recorded during shake table tests of six wall specimens, the effect and contribution of steel reinforcement to peak shear strength and displacement capacity of low-rise concrete walls is assessed and discussed. The experimental program included four variables such as wall geometry, concrete type, web steel ratio and type of web reinforcement. Wall response was assessed through effective steel strains in vertical reinforcement, efficiency factors of wall reinforcement, contribution of web horizontal reinforcement to wall shear strength, and the effect of type of web reinforcement to wall displacement.

Lesions of the orbitofrontal cortex do not affect the reinforcement omission effect in rats

Judice-Daher,Danielle Marcilio; Bueno,José Lino Oliveira
Fonte: Pontificia Universidade Católica do Rio de Janeiro; Universidade de Brasília; Universidade de São Paulo Publicador: Pontificia Universidade Católica do Rio de Janeiro; Universidade de Brasília; Universidade de São Paulo
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2013 EN
Relevância na Pesquisa
36.84%
The reinforcement omission effect (ROE), reflected by response rates that are higher after reinforcement omission than after reinforcement delivery, has been attributed to both motivational and attentional consequences of the surprising reinforcement omission. These processes depend on the operation of separate amygdala areas and their connections with other brain systems. The interaction between the amygdala and orbitofrontal cortex has been suggested to be important in the modulation of motivational processes. The present study sought to verify whether the mechanisms involved in the ROE depend on the integrity of the orbitofrontal cortex. Prior to acquisition training, rats received bilateral excitotoxic lesions of the orbitofrontal cortex or sham lesions. Following postoperative recovery, the rats were trained on a fixed-interval 12 s limited-hold 6 s signaled schedule of reinforcement. After the acquisition of stable performance, the training was changed from a 100% to 50% schedule of reinforcement. The results showed that rats in both groups exhibited the ROE, with no differences in performance between groups following nonreinforcement. These data do not support the hypothesis that the orbitofrontal cortex is included in the neural substrates related to ROE modulation. The results also showed no difference in response rates between groups in the periods that preceded and followed nonreinforcement. These findings confirm previous studies that showed that the ROE is not related to the facilitation of behavior induced by nonreinforcement.

Resistência à tração de pinos de ancoragem isolados e pré-instalados : Influência da armadura de flexão e de cisalhamento; Tensile strenght of anchor bolts isolated and pre-installed - influence of the flexural and shear reinforcement

FONTENELLE, Emmele Gonella
Fonte: Universidade Federal de Goiás; BR; UFG; Mestrado em Engenharia Civil; Engenharias Publicador: Universidade Federal de Goiás; BR; UFG; Mestrado em Engenharia Civil; Engenharias
Tipo: Dissertação Formato: application/pdf
POR
Relevância na Pesquisa
36.87%
Fastenings inserted in concrete are used in order to allow the introduction of these components in concrete structures, enabling the structural link between metal structures and concrete foundation and between prefabricated components and fixing reinforcement elements. This work will study specifically an anchoring system pre-installed (cast-in-place anchor), consisting of single head studs with square head and subjected to tensile force. Assays were performed in 30 headed studs, using self-compacting concrete with compressive strength in the C-30 class. The main variables are the presence and rate of reinforcement, the arrangement of reinforcement in the blocks, and the influence of both the flexural reinforcement (longitudinal and transverse) and the shear reinforcement (hairpins) on the load capacity of the anchorage. The experimental results were compared with five methods of design found in the literature and show that the flexural einforcement has no effect in increasing the load capacity of the anchorage. The use of a shear reinforcement together with the flexural reinforcement can increase the capacity of the anchor up to 64%. Increasing the distance of the hairpins in relation to the head stud reduces the ultimate load achieved by the anchoring system while the increase in diameter and / or in the number of layers of hairpins can increase the ultimate load.; Pinos de ancoragem inseridos em concreto são empregados com a finalidade de permitir a fixação de elementos para a introdução de solicitações nas estruturas de concreto...

Comparação experimental entre tipos de armadura de cisalhamento para combate à punção em lajes cogumelo de concreto armado: Stud rails e Double headed studs; Comparison between experimental types of shear reinforcement to combat punch mushroom slabs of concrete, "Stud rails" and "Double headed studs"

RODRIGUES, David Rosa
Fonte: Universidade Federal de Goiás; BR; UFG; Mestrado em Engenharia Civil; Engenharias Publicador: Universidade Federal de Goiás; BR; UFG; Mestrado em Engenharia Civil; Engenharias
Tipo: Dissertação Formato: application/pdf
POR
Relevância na Pesquisa
36.87%
This research presents the results of an experimental comparison between the types of shear reinforcement "stud rails" and "double headed studs" to combat the punching shear of a reinforced concrete flat slabs. It also presents a comparison of experimental results with those provided under the ACI 318/2005, CEB-FIP MC/1990, EUROCODE 2/2004 and NBR 6118:2003. The motivation was to investigate the efficiency of these shear reinforcement for the differences between them. It was tested six slabs of concrete to concentric load, with dimensions of 2400 mm x 2400 mm x 150 mm. It was concreted a column of section 500 mm x 200 mm to 850 mm total height next to the slab. The main variables were the type of shear reinforcement "stud rails" x "double headed studs, the "studs" diameter and the shear reinforcement area per layer. The slabs were tested until the failure. It was monitored the deflection, reinforcement deformation of bending and shear. All slabs failed by punching with internal surface rupture. The experimental results after being compared with the expected standard in each individual calculation showed conservative values. Slabs of Group 1 with "stud rails" presented failed loads greater than those in Group 2 with "double headed studs. Codes/standards 318/2005 ACI...

The effects of pleiotropic traits important for local assortative mating on reinforcement, cascade speciation, and diversification

Castillo, DM; Gibson, AK; Moyle, LC
Fonte: Current Zoology Publicador: Current Zoology
Tipo: Relatório
EN
Relevância na Pesquisa
36.87%
Cascade speciation and reinforcement can evolve rapidly when traits are pleiotropic and act as both signal/cue in non-random mating. Reproductive isolation due to these traits can be rapid, facilitating cascade speciation by limiting gene flow among sympatric and allopatric populations of the same species. Here we examine the evolution of two key traits-- assortative mating and self-fertilization--and their possible contribution to reinforcement and (by extension) cascade speciation. First, we use a population genetic model of reinforcement to address conditions that favor the evolution of assortative mating and/or self-fertilization in the face of deleterious gene flow from a heterospecific population. Our results indicate that, although both traits can contribute to reinforcement independently, when they are allowed to evolve simultaneously the evolution of increased self-fertilization prohibits the evolution of assortative mating, at least when inbreeding depression is low or moderate. Thus we predict that, under conditions of low inbreeding depression, mating system transitions are more likely to be involved in reinforcement and consequently cascade speciation, than assortative mating. Given that transitions to self-fertilization might be an important driver of reinforcement and cascade speciation we analyzed comparative data from two different groups to address the effects of self-fertilization on clade-wide diversification. We find mixed evidence for an association between self-fertilization and diversification: self-fertilization is associated with reduced diversification rates in the plant genus Mimulus (as found in several other plant groups) however we see a trend towards uniparental reproductive modes being associated with increased diversification rate in the Nematode phylum. Reinforcement driving speciation via transitions to self-fertilization might be short lived and/or unsustainable across longer time scales in plants...

TIME-DEPENDENT PERFORMANCE OF COLUMN-SUPPORTED EMBANKMENTS INVOLVING VISCOUS REINFORCEMENT AND PREFABRICATED VERTICAL DRAINS

LIU, KAIWEN
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
EN; EN
Relevância na Pesquisa
36.89%
A fully 3D coupled finite element (FE) analysis is performed to examine the performance of four sections of a full-scale embankment on soft soils. The proposed FE model successfully captures the behaviour of full scale embankments involving geosynthetic-reinforced and piled sections, and the observed difference in performance of different improvement techniques, with respect to pore-water pressures, settlements, subsoil stresses, lateral displacements below the toe of the embankments, and reinforcement strains. The effects of geosynthetic reinforcement and multi-layers of reinforcement on the performance of the pile-supported embankment are discussed. The relative load transfer is calculated using eight existing methods and they are compared with the field measurements and numerical results. Deep-mixing-method (DMM) columns which are less rigid than piles are increasingly used as a cost-effective soft ground improvement technique. The influence of reinforcement viscosity on the post-construction performance of embankments with DMM floating columns and fully penetrating columns is investigated using the 3D FE coupled model verified by aforementioned field case. It is shown that the viscous behaviour behaviour of geosynthetic reinforcement can increase the long-term shear deformations of foundation soil and also the horizontal toe movement. The DMM column-supported embankments with viscous and with inviscous reinforcement are numerically constructed to identify the effect and magnitude of reinforcement creep and stress relaxation. It is shown that consideration of time-varying subsoil hydraulic conductivity has an important effect on time-dependent embankment behaviour particularly with respect to horizontal toe movement of reinforced and DMM floating-column supported embankments under working conditions. The potential interacting factors of the construction rate...

Análise teórica e experimental de vigas de concreto armado com armadura de confinamento; Theoretical and experimental analysis of reinforced concrete beams with confinement reinforcement

Delalibera, Rodrigo Gustavo
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 29/04/2002 PT
Relevância na Pesquisa
36.89%
Este trabalho discute a utilização de armadura de confinamento em vigas superarmadas de concreto armado. Essa armadura é constituída de estribos quadrados colocados na região de compressão da seção transversal da viga, aumentando a ductilidade. Para a análise numérica, utilizou-se programa computacional baseado no Método dos Elementos Finitos e que leva em consideração o efeito do confinamento no concreto, possibilitando estudar criteriosamente a influência da armadura de confinamento em vigas superarmadas. Na etapa experimental foi investigada a influência da taxa volumétrica da armadura transversal de confinamento, sendo realizados ensaios de quatro vigas superarmadas -três detalhadas com estribos adicionais destinados ao confinamento e uma projetada sem armadura de confinamento. Todas as vigas tiveram deformações nas barras da armadura de tração próximas a 'épsilon' y e resistência média à compressão do concreto de 25MPa. Os resultados experimentais mostraram que o índice de ductilidade pós-pico é proporcional à taxa volumétrica da armadura transversal de confinamento. Isso não aconteceu para o índice de ductilidade pré-pico, que teve variação aleatória com a taxa volumétrica de armadura de confinamento. Observou-se também que a resistência à compressão do concreto confinado no núcleo de confinamento diminuiu na proximidade da linha neutra. Considerando os resultados numéricos e experimentais...

Effective reinforcement learning following cerebellar damage requires a balance between exploration and motor noise; Cerebellar damage and reinforcement learning

Therrien, Amanda S.; Wolpert, Daniel M.; Bastian, Amy J.
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Article; published version
EN
Relevância na Pesquisa
36.95%
This is the final version of the article. It was first available from Oxford University Press via http://dx.doi.org/10.1093/brain/awv329; Reinforcement and error-based processes are essential for motor learning, with the cerebellum thought to be required only for the error-based mechanism. Here we examined learning and retention of a reaching skill under both processes. Control subjects learned similarly from reinforcement and errorbased feedback, but showed much better retention under reinforcement. To apply reinforcement to cerebellar patients, we developed a closed-loop reinforcement schedule in which task difficulty was controlled based on recent performance. This schedule produced substantial learning in cerebellar patients and controls. Cerebellar patients varied in their learning under reinforcement but fully retained what was learned. In contrast, they showed complete lack of retention in error-based learning. We developed a mechanistic model of the reinforcement task and found that learning depended on a balance between exploration variability and motor noise. While the cerebellar and control groups had similar exploration variability, the patients had greater motor noise and hence learned less. Our results suggest that cerebellar damage indirectly impairs reinforcement learning by increasing motor noise...

Contingency and contiguity on the responding by rats exposed to variable interval, variable ratio and variable time schedules of reinforcement; Contingência e contigüidade no responder de ratos submetidos a esquemas de razão, intervalo e tempo variáveis

Fonseca, Cristina Moreira; Tomanari, Gerson Yukio
Fonte: UFPR Publicador: UFPR
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; avaliado por pares; Formato: application/pdf
Publicado em 27/06/2008 POR
Relevância na Pesquisa
36.92%
In this study, we examined the effects of introducing a delay of reinforcement on the rate and distribution of lever-pressing of eight rats under interval, ratio, and time reinforcement schedules (VI, VR, and VT). Following baseline conditions under immediate reinforcement, an unsignaled and nonresetting 5-s delay of reinforcement was introduced upon each of these schedules. Results showed that the delay was accompanied by a decrease in the rate of responses for all subjects, for all three schedules of reinforcement, most noticeable for VT, followed by the VI and then the VR schedules. A molecular analysis of the data revealed that, under VI, but not VR, the subjects' actual delay approximated the programmed value of 5 seconds. In general, results demonstrate that the effects of introducing a delay of reinforcement depend on the current reinforcement schedule. In the present study, in particular, response rate and response distribution under VI and VR, were followed by different effects of the delay when controlling respectively for time and ratio of responses.Keywords: contingency; contiguity; delay of reinforcement; schedules of reinforcement; rats. ; No presente estudo, foram investigados os efeitos produzidos pela introdução de atraso do reforço sobre a taxa e a distribuição de freqüência das respostas de pressão à barra emitidas por oito ratos expostos a esquemas de intervalo...

Efeitos paramétricos do atraso do reforço sobre o responder de ratos submetidos a esquemas de razão e intervalos variáveis; Parametrical Effects of Delayed Reinforcement on the Responding of Rats Exposed to Variable Interval and Variable Ratio Schedules

Fonseca, Cristina Moreira; Instituto de Psicologia, Universidade de São Paulo; Tomanari, Gerson Yukio; Instituto de Psicologia, Universidade de São Paulo
Fonte: UFPR Publicador: UFPR
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; avaliado por pares; Formato: application/pdf
Publicado em 14/04/2010 POR
Relevância na Pesquisa
36.89%
This study examined the effects of introducing different delays of reinforcement on the rate of lever pressing by eight rats under variable interval and variable ratio schedules (VI and VR, respectively). Following baseline conditions under immediate reinforcement, unsignaled and non-resetting delays of reinforcement were introduced upon each of these schedules. In different conditions, delays of 2 s, 5 s and 8 s were presented in both increasing and decreasing sequences. The results showed negative correlations between rate of responding and delay of reinforcement for most subjects and delays. By analyzing the frequency distribution of the delays actually obtained in each single reinforcer delivery, it was possible to verify a higher concentration of 0.5-s delays when a 2-s delay was programmed. In contrast, actual delays concentrated around 5 s and 8 s when the programmed delays were 5 s and 8 s, respectively. Such differential effects generated by the delays of reinforcement on responding can be understood by analyzing how the delay affected the ongoing contingencies in each particular schedule.                                                                   Keywords: delay of reinforcement; schedules of reinforcement; variable interval; variable ratio; rats.; Foram investigados os efeitos produzidos pela introdução de diferentes valores de atraso do reforço sobre as respostas de pressão à barra emitidas por oito ratos expostos a esquemas de intervalo e razão variáveis (VI e VR...

Efeitos de histórias de reforço social sobre o seguir regras; Effects of social reinforcement histories on rule-following

Albuquerque, Luiz Carlos de; Universidade Federal do Pará; Matsuo, Gilsany Leão; Universidade Federal do Pará; Paracampo, Carla Cristina Paiva; Universidade Federal do Pará
Fonte: UFPR Publicador: UFPR
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; avaliado por pares; Formato: application/pdf
Publicado em 14/04/2010 POR
Relevância na Pesquisa
36.89%
The objective was to study the effects of social reinforcement histories on rule-following using 12 undergraduate students exposed to a matching-to-sample procedure. The task was to point out each one of the three comparison stimuli in a given sequence. In both experimental conditions, no sequence was reinforced or instructed in Phase 1. Phase 2 initiated the rule corresponding to the contingencies and Phase 3 with the rule that was discrepant to the contingencies. In Phases 2 and 3, the only reinforced sequence was the one specified by the correspondent rule of Phase 2. The two conditions differed in the consequences programmed for the correct sequence. The correct sequence would produce social reinforcement in Condition 1 and would produce social reinforcement, plus points exchangeable for money in Condition 2. The correct sequence was reinforced in continuous reinforcement. All 12 participants followed the correspondent rule in Phase 2. In Phase 3, four out of six participants in Condition 1 and three out of six participants in Condition 2 followed the discrepant rule. It is suggested that a history of social reinforcement for following a correspondent rule can contribute to maintain a subsequent following of a rule discrepant from the contingencies. Keywords: contingencies of reinforcement; social reinforcement history; instructional control.; Com o objetivo de investigar os efeitos de histórias de reforço social sobre o seguimento de regras...

Response acquisition with Delayed Conditioned Reinforcement

Sosa,Rodrigo; Pulido,Marco A.
Fonte: Sociedad Mexicana de Análisis de la Conducta Publicador: Sociedad Mexicana de Análisis de la Conducta
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2011 EN
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The present study assessed the possibility that lever pressing by rats, will increase, if this response is correlated with the presentation of exteroceptive stimuli, previously paired with primary reinforcement. Naïve rats were exposed to ten 30 minute sessions where a FT 60-s schedule presented food correlated with a 3-s blackout and the operation of the food delivery magazine. After the training phase was over, an acquisition phase began, subjects could receive one of four different schedules for twenty consecutive sessions: 1) CRF; 2) FR1, FT 2-s; 3) FR1, FT 5-s or 4) FR1, FT 10-s; nine subjects were exposed to each schedule. Results produced by the conditioned reinforcement conditions were compared with conditions where: 1) primary reinforcement was delivered during the acquisition phase, 2) blackout and magazine operation occurred during the training phase but in the absence of food, and 3) subjects remained in the experimental chamber without any programmed stimulus presentation during the training phase. Both the primary reinforcement and the conditioned reinforcement conditions produced delay gradients; the latter was considerably steeper than the former. Results were discussed in terms of their similarity with previous studies; they were also discussed in terms of the ongoing debate regarding the empirical validity of the conditioned reinforcement concept.