An n-armed bandit task was used to investigate the trade-off between exploratory (choosing lesser-known options) and exploitive (choosing options with the greatest probability of reinforcement) human choice in a trial-and-error learning problem. In Experiment 1 a different probability of reinforcement was assigned to each of 8 response options using random-ratios (RRs), and participants chose by clicking buttons in a circular display on a computer screen using a computer mouse. Relative frequency thresholds (ranging from .10 to 1.0) were randomly assigned to each participant and acted as task constraints limiting the proportion of total responses that could be attributed to any response option. Preference for the richer keys was shown, and those with greater constraints explored more and earned less reinforcement. Those with the highest constraints showed no preference, distributing their responses among the options with equal probability. In Experiment 2 the payoff probabilities changed partway through, for some the leanest options increased to richest, and for others the richest became leanest. When the RRs changed, the decrease participants with moderate and low constraints showed immediate increases in exploration and change in preference to the new richest keys, while increase participants showed no increase in exploration, and more gradual changes in preference. For Experiment 3 the constraint was held constant at .85, and the two richest options were decreased midway through the task by varying amounts (0 to .60). Decreases were detected early for participants in all but the smallest decrease conditions, and exploration increased.

We manipulated delay and magnitude of reinforcers in two concurrent schedules of reinforcement to decrease a prevalent behavior while increasing another behavior already in the participant's repertoire. The first experiment manipulated delay, implementing a five second delay between the behavior and delivery of reinforcement for a behavior targeted for decrease while no delay was implemented after the behavior targeted for increase. The second experiment manipulated magnitude, providing one piece of food for the behavior targeted for decrease while two pieces of food were provided for the behavior targeted for increase. The experiments used an ABAB reversal design. Results suggest that behavior can be decreased without the use of extinction when contingencies favor the desirable behavior.

The purpose of this experiment was to evaluate the effects of alternative contingencies on instruction following by an ABA design. Three college students consistently pressed keys 1-5-3 and 4-8-6 in the presence of the written instruction "Press 153" or "Press 486." During condition A, the contingencies for following and not following the instruction were the same: CON FR5 FR5 and CON FR20 FR20. During condition B, the contingencies for following and not following the instruction were different: CON FR20 FR5. For one participant, the schedule of reinforcement was then changed to FR30. The results showed that subjects followed instructions when the schedule of reinforcement was the same for instruction following and not following.

Os estudos sobre escolha e preferência do comportamento individual a partir de esquemas concorrentes tornaram mais clara a função relativa do reforço no comportamento. No nível cultural, por sua vez, não há estudos experimentais sobre a função relativa de consequências culturais a partir de metacontingências concorrentes, o que certamente limita a compreensão do que leva um grupo a escolher/preferir engajar-se em uma prática em detrimento de outra. O presente trabalho teve o objetivo de aferir experimentalmente a frequência relativa de duas contingências comportamentais entrelaçadas (CCEs) como função da exigência de dois esquemas de razão concorrentes para produção de consequências culturais. Os esquemas de razão para cada contingência entrelaçada foram diferentes a depender da condição (conc FR1 FR1, FR1 FR2, FR1, FR3, FR2 FR2 e FR2 FR3). As duas contingências entrelaçadas relevantes para a produção de consequências culturais foram descritas na instrução, de modo a reduzir variações. Participaram do estudo 12 estudantes universitários divididos em quatro tríades. A tarefa experimental consistiu na escolha de linhas de uma matriz composta por dez linhas e dez colunas, sendo as linhas compostas por cinco cores diferentes alternadas, de modo que cada cor estivesse presente em uma linha par e outra ímpar. Consequências individuais (ganho de fichas trocáveis por dinheiro) foram contingentes a escolhas de linhas ímpares. Consequências culturais (itens escolares a serem doados a uma instituição) foram contingentes a sequências específicas de cores, que correspondiam às escolhas de linhas por cada um dos três participantes. Teve-se como resultados que as Tríades I e II tenderam à estereotipia da CCE associada ao esquema de menor razão ao final das condições, o que não ocorreu para as Tríades III e IV. Para as Tríades I e II, variações tenderam a ocorrer após mudanças de condições em que havia aumento da intermitência de consequências culturais associadas à CCE mais frequente. Também para as Tríades I e II, verbalizações sobre o procedimento foram mais frequentes nos períodos em que variações entre as CCEs relevantes foram mais frequentes. Para as Tríades III e IV, durante a maior parte do estudo não houve diferenciação da frequência entre as duas CCEs às quais consequências culturais eram contingentes, embora tenha havido diferenciação das duas CCEs em relação a outras / Studies about choice and preference using concurrent schedules contributed to better understand the relative function of the reinforcer on behavior. However, at the cultural level there are no experimental studies regarding the relative function of cultural consequences using concurrent metacontingencies, which certainly restricts the understanding about which variables lead a group to choose or prefer to engage in a practice over another. The objective of this experimental study was to assess the relative frequency of two interlocking behavior contingencies (IBCs) as a function of two fixed ratio schedules to produce cultural consequences. The ratio schedules to each interlocking contingency were different depending on the condition (conc FR1 FR1, FR1 FR2, FR1 FR3, FR2 FR2 and FR2 FR3). Both relevant interlocks for the production of cultural consequences were described in the instructions in order to reduce variability. 12 college students participated, divided into four triads. The experimental task consisted of row choices in a matrix comprising ten rows and ten columns, the rows being composed of five different colors, so that each color was present in an even and in an odd row. Individual consequences (earn of coins interchangeable for money) were contingent to the choice of odd rows. Cultural consequences (school supplies to be donated) were contingent to specific sequences of colors that corresponded to the combined row choices of the three participants. The results showed that Triads I and II leaned towards IBC stereotypy associated to the low ratio schedule at the end of the conditions, which did not occur for Triads III and IV. Triads I and II showed that variations tended to occur after experimental condition changes in which there were increased of the ratio schedule to cultural consequences associated to the more frequent IBC. Also, for Triads I and II, verbalizations about the procedure were more frequent when variations between the two IBCs were higher. For Triads III and IV, for most of the study there was no difference in frequency of the two relevant IBCs, although there was difference between the two relevant IBCs in relation to others

Os estudos sobre escolha e preferência do comportamento individual a partir de esquemas concorrentes tornaram mais clara a função relativa do reforço no comportamento. No nível cultural, por sua vez, não há estudos experimentais sobre a função relativa de consequências culturais a partir de metacontingências concorrentes, o que certamente limita a compreensão do que leva um grupo a escolher/preferir engajar-se em uma prática em detrimento de outra. O presente trabalho teve o objetivo de aferir experimentalmente a frequência relativa de duas contingências comportamentais entrelaçadas (CCEs) como função da exigência de dois esquemas de razão concorrentes para produção de consequências culturais. Os esquemas de razão para cada contingência entrelaçada foram diferentes a depender da condição (conc FR1 FR1, FR1 FR2, FR1, FR3, FR2 FR2 e FR2 FR3). As duas contingências entrelaçadas relevantes para a produção de consequências culturais foram descritas na instrução, de modo a reduzir variações. Participaram do estudo 12 estudantes universitários divididos em quatro tríades. A tarefa experimental consistiu na escolha de linhas de uma matriz composta por dez linhas e dez colunas, sendo as linhas compostas por cinco cores diferentes alternadas, de modo que cada cor estivesse presente em uma linha par e outra ímpar. Consequências individuais (ganho de fichas trocáveis por dinheiro) foram contingentes a escolhas de linhas ímpares. Consequências culturais (itens escolares a serem doados a uma instituição) foram contingentes a sequências específicas de cores, que correspondiam às escolhas de linhas por cada um dos três participantes. Teve-se como resultados que as Tríades I e II tenderam à estereotipia da CCE associada ao esquema de menor razão ao final das condições, o que não ocorreu para as Tríades III e IV. Para as Tríades I e II, variações tenderam a ocorrer após mudanças de condições em que havia aumento da intermitência de consequências culturais associadas à CCE mais frequente. Também para as Tríades I e II, verbalizações sobre o procedimento foram mais frequentes nos períodos em que variações entre as CCEs relevantes foram mais frequentes. Para as Tríades III e IV, durante a maior parte do estudo não houve diferenciação da frequência entre as duas CCEs às quais consequências culturais eram contingentes, embora tenha havido diferenciação das duas CCEs em relação a outras / Studies about choice and preference using concurrent schedules contributed to better understand the relative function of the reinforcer on behavior. However, at the cultural level there are no experimental studies regarding the relative function of cultural consequences using concurrent metacontingencies, which certainly restricts the understanding about which variables lead a group to choose or prefer to engage in a practice over another. The objective of this experimental study was to assess the relative frequency of two interlocking behavior contingencies (IBCs) as a function of two fixed ratio schedules to produce cultural consequences. The ratio schedules to each interlocking contingency were different depending on the condition (conc FR1 FR1, FR1 FR2, FR1 FR3, FR2 FR2 and FR2 FR3). Both relevant interlocks for the production of cultural consequences were described in the instructions in order to reduce variability. 12 college students participated, divided into four triads. The experimental task consisted of row choices in a matrix comprising ten rows and ten columns, the rows being composed of five different colors, so that each color was present in an even and in an odd row. Individual consequences (earn of coins interchangeable for money) were contingent to the choice of odd rows. Cultural consequences (school supplies to be donated) were contingent to specific sequences of colors that corresponded to the combined row choices of the three participants. The results showed that Triads I and II leaned towards IBC stereotypy associated to the low ratio schedule at the end of the conditions, which did not occur for Triads III and IV. Triads I and II showed that variations tended to occur after experimental condition changes in which there were increased of the ratio schedule to cultural consequences associated to the more frequent IBC. Also, for Triads I and II, verbalizations about the procedure were more frequent when variations between the two IBCs were higher. For Triads III and IV, for most of the study there was no difference in frequency of the two relevant IBCs, although there was difference between the two relevant IBCs in relation to others

Students may avoid working on difficult tasks because it takes them longer to complete those tasks, which results in a delay to reinforcement. Research studies show that reinforcer and response dimensions can be manipulated within a concurrent operants framework to bias choice allocation toward more difficult tasks. The current study extends previous literature on concurrent choice assessments by examining the effects of reinforcement schedules and fluency interventions on the choice allocation between low and high effort math tasks. The study was conducted with 4 second graders in an elementary school. The choice assessment conducted prior to fluency training (Phase 1) examined the effects of enriching the reinforcement schedule for the high effort tasks on student choice. During fluency training (Phase 2), strategies to increase fluency rates on high effort tasks were implemented. The choice assessment following fluency training (Phase 3) examined changes in choice pattern when the same choice alternatives were available as in Phase 1. A concurrent schedules with reversal design was used to identify student response allocation to tasks under different reinforcement conditions during the choice assessments. The fluency training phase was conducted as a case study design. The three important findings of this study were: (a) prior to fluency training, the 4 students allocated more time to low effort tasks when equal reinforcement was provided for both types of math tasks; the students then shifted to high effort tasks as the reinforcement schedule was enriched for these tasks; (b) fluency training strategies were effective in increasing the rate at which high effort tasks were accurately completed; and (c) all 4 students switched more quickly to high effort tasks following fluency training. Implications for educators are discussed.

The present study contributes an apparatus and research paradigm useful in generating human performances sensitive to concurrent schedules of reinforcement. Five participants produced performances observed to be under temporal and ratio control of concurrent fixed interval-fixed ratio schedules. Two aspects of interaction between FI and FR schedules were distinguishable in the data. First, interaction between two schedules was observed in that changes in the value of one schedule affected behavior reinforced on another schedule. Second, switching from one pattern to the other functioned as an operant unit, showing stability during schedule maintenance conditions and sensitivity to extinction. These effects are discussed in the context of current views on behavior under concurrent schedules of reinforcement, and some implications for the conceptualization, measurement, analysis, and treatment of complex behavior are presented.

No description available.

Made available in DSpace on 2016-06-02T20:30:11Z (GMT). No. of bitstreams: 1 6760.pdf: 2504221 bytes, checksum: 45e64948f4a0d4d5a9beeab79feef1f1 (MD5) Previous issue date: 2015-03-13 / Financiadora de Estudos e Projetos / Food with high sugar concentration exhibits relation with impulsive eating behavior and obesity. This research investigated the effect of different rates of reinforcement and compositions of food, traditional or light, on the choice responses pattern of four undergraduate students. Those foods have similar organoleptic characteristics and different sugar concentration. One study, whith three phases was did, in all of them, two stimuli representing the initial links of a chain-concurrent schedule were presented, simultaneously, to the participants in a computer screen. Choice response in the initial links was followed by the second link of the chain-concurrent schedule. In Phase 1, response in FR1 on the second link was followed by the delivering, in both alternatives, of juice samples with the same composition, flavor and magnitude, an inter-trial interval and another trial. In Phase 2, response in FR1 on the second link was followed by the delivering of samples of traditional juice composition on one terminal link of the chain-concurrent schedule or light juice composition on another terminal link of the chain-concurrent schedule, an inter-trial interval and another trial. In Phase 3, was added primarily contextual stimuli consistent with the structural arrangement indicating which composition would have the juice samples available for each alternative and later this contextual stimuli became inconsistent with the structural arrangement. The sessions presented varied in time. The maximum duration was 10 minutes and occurred, on average, three times a week. The results showed that human subjects have difficult to exhibit maximization in chain-concurrent schedule, have good sensitivity to the different reinforcement rates in chain-concurrent schedule and concentrations of sugar in samples of traditional and light juices composition. / Alimentos com alta concentração de açúcar apresentam relação com comportamento alimentar impulsivo e obesidade. Esta pesquisa investigou o efeito que diferentes taxas de reforçamento e composições de alimentos, tradicional ou light, exerciam no comportamento de escolhas de quatro universitários. Tais alimentos apresentavam características organolépticas similares e diferiam apenas quanto à concentração de açúcar. Um estudo, contendo três fases, foi realizado com dois estímulos representando os elos iniciais de esquemas de reforçamento concorrentes encadeados apresentados, simultaneamente, aos participantes na tela do computador. Respostas nos elos iniciais foram seguidas pelo segundo elo do esquema encadeado. Na Fase 1, respostas em FR1 no segundo elo foram seguidas pela apresentação, em ambas as alternativas, de amostras de sucos de mesma quantidade, mesmo sabor e mesma composição, um intervalo intertentativas e o início de uma nova tentativa. Na Fase 2, respostas em FR1 no segundo elo foram seguidas pela apresentação de amostras de sucos de mesma quantidade, mesmo sabor, porém de composição tradicional em um elo terminal e light no outro elo terminal, um intervalo intertentativas e o início de uma nova tentativa. Na Fase 3, foram adicionados, primeiramente, dois estímulos contextuais consistentes com o arranjo estrutural, indicando a composição das amostras de suco que seriam disponibilizadas em cada alternativa. Posteriormente, os estímulos contextuais se tornaram inconsistentes com o arranjo estrutural, indicando erroneamente a composição das amostras de suco que seriam disponibilizadas em cada alternativa. As sessões ocorreram em média três vezes na semana e apresentaram tempo variado, tendo 10 minutos de duração a mais longa. Os resultados mostram que humanos têm dificuldades de emitir padrão maximizado de escolhas em esquemas de reforçamento concorrentes encadeados, que apresentam alta sensibilidade em relação às diferentes taxas de reforço dos esquemas concorrentes e discriminam as concentrações de açúcar de amostras de sucos de composição tradicional e light.

Made available in DSpace on 2016-04-29T13:18:06Z (GMT). No. of bitstreams: 1 diss completa.pdf: 1344921 bytes, checksum: 0d5eb60c4e0b5309d3eaeef2b4c9187d (MD5) Previous issue date: 2001-09-28 / Fundação de Amparo a Pesquisa do Estado de São Paulo / Chronic Mild Stress (CMS) is an experimental model for depression: Rats are submitted to a set of stressing conditions and as a result their consumption of water and water with sucrose, as well as the animals previous preference for water and water and sucrose also drops. It is argued that the stress changes the organism and, consequently, changes the reinforcing properties of water and water with sucrose. Therefore the stress would make the subjects insensible to reward. The present study investigated if what has been called sensitivity to reward could be described as a drop in the reinforcing value of a reinforcer. In other words, one of this study's goals was to evaluate if a protocol of mild stress diminished the reinforcing value of a known reinforcer, here, water with sucrose. Four male rats were submitted to a stress protocol of six weeks (as described by Willner, Towell, Sampson, Sophokleus e Muscat (1987). Two of them were also submitted to operant sessions of a FR-FR concurrent schedule of reinforcement, with responses followed either by water or water with sucrose prior and after the stress protocol. Results showed that all four subjects diminished their overall liquid consumption while the stress protocol was in effect. Results also showed the two subjects preferred water with sucrose on the FRFR condition (with higher rates of responses on the lever associated with water with sucrose), and that these subjects recovered their overall consumption and their preference for water with sucrose faster than the two subjects not submitted to the operant condition / Chronic Mild Stress (CMS) é um modelo animal experimental proposto como um modelo de depressão, ao qual ratos são submetidos. Após passarem por um conjunto de "situações de estresse suave", o consumo de água e de água com sacarose desses animais decresce. Considera-se que a submissão ao conjunto de estressores modifica o organismo e, consequentemente, a propriedade recompensadora da água e da água com sacarose. Supõe-se, então, que o sujeito toma-se "Insensível" à recompensa. O presente estudo pretendeu replicar os resultados de Willner, Towell, Sampson, Sopholeus e Muscat (1987) e também verificar se o que é denominado "Insensibilidade à recompensa" poderia ser descrito como diminuição do valor reforçador do estímulo, uma vez que este estímulo, nos estudos de CMS, não é produzido sistematicamente por uma ação/resposta dos sujeitos sistematicamente medida. Ou seja, a submissão ao "regime de estresse" afetaria o valor reforçador do estímulo? Ratos machos foram sujeitos. Dois sujeitos foram submetidos a um conjunto de condições de estresse suave, por 6 semanas, conforme descritos por Willner e cols. (1987), como por exemplo, privação de água e comida, barulho intermitente, iluminação contínua, agrupamento de dois sujeitos na mesma gaiola, luz estroboscópica, cheiro, apresentação de uma garrafa vazia após privação de água, acesso restrito a comida, inclinação da gaiola, presença de um objeto estranho na gaiola e chão da gaiola sujo. Verificou-se uma diminuição no consumo total de líquido e na preferência por água com sacarose destes sujeitos durante e após este procedimento. Outros dois sujeitos foram submetidos a sessões operantes sob um esquema concorrente FR15-FRI5 com água e água com sacarose como estímulos reforçadores antes e após a submissão ao mesmo conjunto de estressores. Também com estes sujeitos observou-se diminuição no consumo de líquido e na preferência por água com sacarose em testes semanais de consumo de líquido, durante as semanas de exposição ao estresse, o que indicaria um aparente efeito do regime de estresse sobre o valor reforçador dos estímulos. Observou-se também, com estes sujeitos, que a submissão à condição operante após o período de estresse parece ter alterado o efeito produzido pelo CMS, aumentando o consumo de líquido e a preferência pela água com sacarose nos testes realizados nas semanas seguintes à exposição ao regime de estresse