The purpose of the current study was to examine the effects of using fixed time schedules with different magnitudes of stimulus delivery as treatment for pica. A functional assessment was conducted, which indicated that pica occurred across experimental conditions and was most frequent in the absence of social stimulation or contingencies. A competing stimulus assessment was then conducted to identify stimuli that could potentially compete with pica during NCR. Subsequently, an evaluation of the effects of reinforcer magnitude on NCR as a treatment of pica was conducted. Treatment results indicated that quantity of reinforcer increased the effectiveness of leaner schedules of reinforcer delivery; however, it was not possible to fade the temporal schedule to one that would have been useful in practice. In addition, limitations and future research are outlined.

Understanding dimensions that influence reinforcement is important for applied behavior analysts. Preference, and reinforcer effectiveness, may change depending upon several dimensions of reinforcement. Two influential dimensions that may influence preference and reinforcer efficacy are response-reinforcer arrangements and stimulus type. Many leisure items used as reinforcers may be classified depending upon technology level (e.g., highly technological items versus non-technological items). In recent years use of highly technological items has increased among individuals with disabilities. When using high- and low-tech reinforcers, reinforcer deliveries may be arranged to occur in a distributed manner (i.e., every response results in a reinforcer delivery), or an accumulated manner (i.e., reinforcers are accumulated and exchanged following completion of all the work). The purpose of this study was to examine the interaction and effects of reinforcer arrangements (i.e., distributed reinforcement and accumulated reinforcement) and technology level of items (i.e., high-tech and low-tech) on preference and reinforcer efficacy with three children with autism. Results demonstrated higher response rates and preference toward accumulated reinforcer arrangements compared to distributed reinforcer arrangements regardless of technology level. Overall, participants’ responding and preference were sensitive to different reinforcer arrangements but were less sensitive to differences in the technology level of the reinforcers used.

Two dimensions of reinforcement that influence behavior are reinforcer magnitude and stimulus type. One type of stimulus involving high technology (i.e., hightech stimuli) has not been examined to determine reinforcement properties. This project examined the interactions of reinforcer magnitude and high-tech stimuli and the effects of those interactions on preference and reinforcer efficacy. Participants included three adult individuals with disabilities. Two multiple stimulus without replacement (MSWO) preference assessments were conducted to determine a highly preferred high-tech stimulus and a highly preferred no-tech stimulus for each participant. A paired stimulus preference assessment was conducted to identify preferred reinforcer magnitudes using both highly preferred stimuli (high- and no-tech). A progressive ratio (PR) reinforcer assessment was then conducted to assess the effects of stimulus type and reinforcer magnitude on reinforcer efficacy. Results demonstrated a preference for high-tech stimuli at longer durations of access for two participants. Results also demonstrated participants responded more for high-tech stimuli as reinforcer magnitudes were increased, and responded less for no-tech stimuli as reinforcer magnitudes were increased (measured as total number of responses during the PR assessments). These results provide further evidence of the effects of reinforcer magnitude and stimulus type (high-tech stimuli) on preference and reinforcer efficacy and have implications for clinicians and caregivers using high- and no-tech items as reinforcers.

Made available in DSpace on 2016-04-29T13:18:18Z (GMT). No. of bitstreams: 1 Lygia T Dorigon.pdf: 1101483 bytes, checksum: b41b65d19a50d4cebbba1a04c5b5206b (MD5) Previous issue date: 2010-05-06 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / An analysis of the publications which dealt with reinforcing stimuli classified according to the conditions of consequences production pointed to diversity in the terminological and conceptual orders. This diversity prevents the construction of a solid theoretical frame about the reinforcing stimuli in issue. For that reason a group of publications was analyzed. The analysis was conducted based on a database developed with passages of these publications. It was selected the paragraphs which contained at least one of a list of key-words related to the issue of interest, all the selected paragraphs were identified according to its original publication, year, chapter and caption. Next, all the paragraphs were classified according to its content; it could be classified as passage which contained a conceptual definition, conceptual implication, exemplification or a part of another subject. The results of these paragraphs analysis indicate that the terms natural reinforcer/reinforcement e automatic reinforcer/ reinforcement were most frequently cited by the authors analyzed. However, it was found that a small number of passages in the analyzed paragraphs were classified as conceptual definition (explicit or partial). The passages which contained the selected key-words were mainly related to implication (theoretical or practical), or offered some kind of exemplification and during the discussion of other subjects. The analysis of the references cited by the authors analyzed indicated the absence of concentration in one specific author or group of authors and the minor articulation between authors who took this theme as their interest. The paragraphs classified as conceptual definition and exemplification lead to a construction of a systematic approach to the reinforcing stimuli classified according to the conditions of consequences production, as follows: a) automatic reinforcer stimulus has a mechanic connection with the response and is part of natural contingencies; b) natural reinforcing stimulus consistently follows a response, it can be mediated, as long as the mediator is not the one who planned the contingency and is part of natural or constructed contingencies; and c) arbitrary or contrived reinforcing stimulus is always mediated by the same individual who arranged or facilitated the contingency in which participates and always participates in contrived contingencies. The passages classified as conceptual implication resulted in the analysis of the discussions about the utilization of contrived or arbitrary reinforcers in natural and applied settings. To the analyzed authors the conditions for the utilization of arbitrary reinforcers are specific and it must be carefully accompanied by its withdrawal planning. These recommendations are discussed based on the critics which were made to the concept of reinforcement and the utilization of reinforcement techniques by cognitive psychologists / Uma análise das publicações que trataram do tema dos estímulos reforçadores classificados quanto às condições de produção das consequências apontou diversidade tanto de ordem terminológica quanto conceitual. Tal diversidade impede a formulação de um corpo teórico consistente sobre o tema dos estímulos reforçadores assim classificados. Por esse motivo, foram analisadas um conjunto de publicações sobre o tema. A análise foi feita a partir de um banco de dados construídos com trechos selecionados destas publicações. Foram selecionados parágrafos que continham pelo menos uma de um conjunto de palavras-chaves relacionadas ao tema de interesse, todos os parágrafos selecionados foram identificados de acordo com a obra, o ano, o capítulo e subtítulo. Em seguida, todos foram classificados de acordo com seu conteúdo, podendo ser considerados trechos que continham definição do conceito, implicação do conceito, exemplificação ou outro assunto. Os resultados da análise destes parágrafos indicaram que os termos natural reinforcer/reinforcement e automatic reinforcer/ reinforcement foram os mais citados pelos autores analisados. No entanto, em relação ao conteúdo dos parágrafos analisados, constatou-se um número reduzido de ocorrências de trechos contendo definição (explícita ou parcial) do conceito. Os trechos contendo as palavras-chaves selecionadoras tratavam principalmente de implicações (teóricas ou práticas), ou ofereciam exemplos e em meio a discussão de outros assuntos (parte de outro assunto). A análise das referências bibliográficas indicou ausência de concentração de referências em um autor ou conjunto de autores específicos e pouca articulação entre aos autores que tomaram como seu objeto esta discussão. Os parágrafos classificados como definição e exemplificação do conceito levaram à formulação de uma sistematização para os estímulos reforçadores classificados com base nas condições de produção das consequências, a saber: a) estímulo reforçador automático, aquele que possui uma conexão mecânica com a reposta e faz parte de contingências naturais; b) estímulo reforçador natural, aquele que segue consistentemente o responder, podendo ser intermediado, desde que não por aquele que planejou a contingência e que faz parte de contingências naturais ou construídas e c) estímulo reforçador arbitrário ou construído que sempre é intermediado pelo mesmo indivíduo que arranjou ou facilitou a contingência da qual participa e sempre participa de contingências construídas. Os trechos classificados como implicação do conceito resultaram na análise das discussões da utilização de reforçadores arbitrários ou construídos, em contexto aplicado e natural. Para os autores analisados as condições de utilização de reforçadores arbitrários ou construídos são específicas e devem cuidadosamente acompanhadas quanto ao planejamento de sua retirada. Discute-se estas recomendações à luz de críticas que foram feitas ao conceito de reforçamento e à utilização de técnicas de reforçamento por psicólogos cognitivistas

Made available in DSpace on 2016-07-27T14:21:40Z (GMT). No. of bitstreams: 1 Adriana da Silva Arantes Campos.pdf: 1130712 bytes, checksum: 034ea15f94e341fbfefc374b94bf4a0f (MD5) Previous issue date: 2009-01-06 / This study examined experientially behaviors considered mental processes by other psychological guidelines, but for Behavior Analysis, founded by the philosophy of Radical Behaviorism proposed by Skinner, are considered private verbal behaviors, as thought. To verify functional relations that artificial contingencies perform on participants performance and the relationship of these artificial contingencies with public and private pre-happenings in a mathematical task of troubleshooting. Two experiments were conducted with 6 participants in a subject design as his own control. Experiment I objected to verify functional relations of public pre-happenins and magnitude of strengthening. Experiment II aimed to verify if participants performance in a mathematical task of troubleshooting is function of artificial contingencies and the relationship of these contingencies with public and private pre-happenins during the task proposed. Results suggested that magnitudes of strengthening defined as points do not interfere in participants performance on solving mathematical equations with unknowns (private behavior), natural reinforcement seems to have controlled participants behavior in this type of task resolution. / O presente estudo analisou experimentalmente comportamentos considerados processos mentais por outras orientações psicológicas, mas que para a Análise do Comportamento, ciência fundamentada pela filosofia do Behaviorismo Radical proposta por Skinner, são considerados comportamentos verbais privados, tal como o pensamento. Com o objetivo de verificar as relações funcionais que contingências arbitrárias exercem sobre o desempenho de participantes e a relação dessas contingências arbitrárias com precorrentes públicos e privados em uma tarefa de solução de problemas matemáticos. Dois experimentos foram conduzidos com 6 participantes com um delineamento do sujeito como seu próprio controle. O Experimento I objetivou verificar as relações funcionais de precorrentes públicos e magnitude do reforço. O Experimento II teve como objetivo verificar se o desempenho dos participantes em uma tarefa de resolução de problemas matemáticos é função de contingências arbitrárias e a relação destas contingências com precorrentes públicos e privados na tarefa proposta. Os resultados sugeriram que magnitudes de reforço definidas como pontos não interferem no desempenho dos participantes em resolver equações matemáticas com incógnitas (comportamento privado), o reforço natural de resolver a tarefa parece ter controlado o comportamento dos participantes neste tipo de tarefa.

Made available in DSpace on 2016-04-29T13:17:34Z (GMT). No. of bitstreams: 1 Luiz Antonio Bernardes.pdf: 1976580 bytes, checksum: 6ad8d0432468ef57ee98d69a20f6acf7 (MD5) Previous issue date: 2011-05-25 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The purpose of this work was to identify the variables that could or couldn‟t contribute to the emission of children responses that would produce larger and delayed reinforcers. This was made in order to answer the following question: which responses children emit while they were waiting for larger and delayed reinforcers? Does it occur chaining or stereotyped behaviors during the waiting period? Are there any relations between what is done and the waiting time so that it would facilitate the waiting period? Can a hand puppet work as an audience to the participants so that it could extend the chain of public events and diminish the chain of covert events? Those children that were waiting in pairs or using a puppet waited for longer periods in order to receive larger and delayed reinforcers? The experimental design was based on the Mischel‟s, Ebbesen e Zeiss (1972) study. Fifteen children participated in the study divided in three experimental conditions: alone , hand puppet and peers . They should wait for 15 minutes so that they would obtain two chocolates. If they didn‟t wait, they should ring a bell and the experimenter would return and the children/child would gain the chocolate that was close to her. The results showed that four of the 15 children didn‟t wait for the whole time. The children emitted 14 categories of responses and the more frequent categories were similar for all of them. In the condition alone it was observed a smaller variation on the distribution of the responses between the categories and a smaller number of responses per minute. The condition hand puppet was the only one in which all the participants waited. However, only one participant emitted public oral verbal responses, which doesn‟t allow the experimenter to say that the hand puppet enhancing the emission of these verbal responses. Otherwise, the report of one of the participants does not allow us to discard it entirely as an audience. The standard of the observed responses on the hand puppet condition was similar to the alone condition, but with a higher average of responses per minute. For the peers condition was possible to observe that an interlocutor facilitated the waiting and enhanced the number of responses in new categories. This condition presented the higher average of responses per minute. The results indicated that oral verbal responses were emitted almost exclusively in this condition. The categorized verbal operants most common were tacts and mands about the experimental condition and unrelated subjects . Stereotypy was observed in only one participant (P5). The low variability in the 'alone' condition and greater variability in the other conditions have revealed that more complex environments allowed the participants to respond into new categories. The children who had longer waiting times were the ones with the most responses per minute and/or responded in as many categories as possible / O objetivo do presente trabalho foi identificar variáveis que poderiam contribuir ou não para que crianças emitissem respostas que produziriam reforçadores maiores e atrasados. A partir de então, responder as seguintes perguntas: quais as respostas que crianças emitem enquanto esperam por reforçadores maiores e atrasados? Dentre as respostas observadas, existem encadeamentos ou estereotipias comportamentais? Existe algum tipo de relação ente o que se faz e o tempo de espera de maneira a facilitar a espera? Um fantoche poderia funcionar como audiência para o participante ampliando assim a cadeia de eventos públicos e diminuindo por sua vez a cadeia de eventos encobertos? Crianças esperando em duplas ou usando um fantoche teriam maiores tempos de espera por reforçadores maiores e atrasados? O arranjo experimental foi baseado nos estudos de Mischel, Ebbesen e Zeiss (1972). Participaram 15 crianças divididas em três condições experimentais: sozinha‟, fantoche‟ e duplas‟. Elas deveriam esperar 15 minutos para obter dois chocolates e caso não esperassem, tocariam um sino, o experimentador retornaria e a criança ganharia o chocolate que estava junto dela. Os resultados mostraram que quatro das 15 crianças, não esperaram o tempo total. As crianças emitiram 14 categorias de respostas e as mais frequentes foram semelhantes para todas. Na condição sozinho‟ houve menor variação na distribuição das respostas entre as categorias e menor número de respostas por minuto. A condição fantoche‟ foi a única em que todos os participantes esperaram. Entretanto apenas um participante emitiu respostas verbais orais públicas, e isto não permite afirmar que o fantoche foi capaz de aumentar a emissão destas respostas verbais. Todavia o relato de um dos participantes não nos permite descartá-lo completamente como audiência. O padrão de respostas observáveis da condição fantoche‟ foi semelhante ao da condição sozinho‟, mas com uma média maior de respostas por minuto. Para a condição duplas‟ foi possível observar que ter um interlocutor facilitou a espera e aumentou o número de respostas em novas categorias. Esta condição apresentou as maiores médias de respostas por minuto. Os resultados indicaram que as respostas verbais orais foram quase que exclusivamente nesta condição e os operantes verbais classificados mais comuns foram tatos e mandos sobre a condição experimental‟ e assuntos não relacionados‟. Foi observada estereotipia em apenas um participante (P5). A pouca variabilidade na condição sozinho‟ e a maior variabilidade nas outras condições permitem afirmar que ambientes mais complexos permitiram a emissão de respostas em novas categorias. As crianças que tiveram tempos de espera mais longos foram as que apresentaram mais respostas por minuto e/ou responderam em tantas categorias quantas possíveis

Made available in DSpace on 2016-04-29T13:17:48Z (GMT). No. of bitstreams: 1 Daniel Carvalho de Matos.pdf: 1928285 bytes, checksum: af4f3292fac23f3743a9598b8984c643 (MD5) Previous issue date: 2013-05-21 / The purpose of this research was to assess the effects of manipulating reinforcer delay and probability over the choices in simple and chained concurrent schedules and if these effects suggest similarities between these two reinforcer parameters. Four experiments were conducted. 12 psychology students from a private university served as participants, three for each experiment. The Experiments 1 and 2 involved choice trials between concurrent chained schedules with two links, with the manipulation of reinforcer magnitude and delay (Experiment 1) and reinforcer magnitude and probability (Experiment 2). In both experiments, the choice of component A, from the first link, produced, after T seconds (Experiment 1) or after a probability P (Experiment 2), the access to a new choice link between the components R1 with a small immediate reinforcer (Experiment 1) or a small and more probable reinforcer (Experiment 2) versus R2 with a larger delayed reinforcer (Experiment 1) or with a large and less probable reinforcer (Experiment 2). Still in the first link, in case the component B was chosen, after T seconds (Experiment 1) or a probability P (Experiment 2), there was a second link in which only one component was available: R2 with a large delayed reinforcer (Experiment 1) or with a large and less probable reinforcer (Experiment 2). As a result, first the participants went through selection conditions in which the larger reinforcer should be preferred over the small one (for both experiments); the immediate reinforcer should be preferred over the delayed one (Experiment 1) and the more probable reinforcer should be preferred over the less probable one (Experiment 2); the small immediate reinforcer should be preferred over the larger delayed reinforcer (Experiment 1) and the small and more probable reinforcer should be preferred over the larger and less probable one (Experiment 2). After this, all participants from both experiments went through conditions in which preference reversals, to the component with the larger and more delayed reinforcer (Experiment 1) or the component with the larger and less probable reinforcer (Experiment 2), were assessed. In Experiment 1, the variable time (T) between the two links was manipulated, involving 7.5 and 15 seconds. As result, the data revealed that preference reversal occurred for all the three participants from Experiment 1, considering that, only for participant P1, the reversal occurred when the time (T) between the two links was 7.5 seconds. Besides, for two of the participants (P1 and P3), most of the choices, on first link, were made on component B (alternative that was called the commitment choice according to the literature). In Experiment 2, preference reversal was assessed when the probability between the two links was 17%. The data revealed that reversal occurred, in the sense that most of the choices were made on the component with the larger and less probable reinforcer for all the three participants (P5, P6 and P7). Only for one of these participants (P6), the component B, from first link, was the most chosen one in two blocks of trials. Even though the data suggested relations with those that were obtained in Experiment 1, with the suggestion that reinforcer delay and probability share similar effects over the choices in chained concurrent schedules, there was a methodological problem in Experiment 2 that makes the comparison more difficult. The fact that the probability of the passage from the first to the second link was very low (17%) limited the number of trials in which participants had the chance to respond on second link. Consequently, the access to the reinforcers happened in only a few occasions. Experiments 3 and 4 involved choice trials between simple concurrent schedules with the manipulation of reinforcer magnitude and delay (Experiment 3) and reinforcer magnitude and probability (Experiment 4). After selection conditions similar to those from the two previous experiments, the participants went through a condition with concurrent FR / FR schedules (with a ratio that could vary from 10 to 80), in which the preference reversal was assessed. The data revealed that reversal occurred for all participants from Experiment 3 (P7, P8 and P9) with preference of the component with the larger and delayed reinforcer and the same happened for two of the participants from Experiment 4 (P11 and P12). The data suggested similarities between the reinforcer delay and probability parameters, considering their effects over choices in simple concurrent schedules. In both experiments other conditions (CRF, SigFR and FI) were conducted to assess if the response pattern produced by the FR would be changed, with most of the choices made on the other component with the small immediate reinforcer (Experiment 3) or the small and more probable reinforcer (Experiment 4). The data revealed that the change occurred only for two of the participants from Experiment 4 (P11 and P12), reinforcing the similarity with the data from a research conducted previously with pigeons as subjects / O objetivo desta pesquisa foi avaliar o efeito da manipulação dos parâmetros de atraso e probalidade do reforço sobre as escolhas em esquemas concorrentes simples e encadeados e se esses efeitos sugerem semelhanças entre esses dois parâmetros. Quatro estudos foram conduzidos. Participaram 12 estudantes universitários do curso de psicologia, sendo três participantes para cada estudo. Os Estudos 1 e 2 envolveram tentativas de escolha entre esquemas concorrentes encadeados com dois elos, com manipulação de magnitude e atraso do reforço (Estudo 1) e magnitude e probabilidade do reforço (Estudo 2). Em ambos os estudos, a escolha do componente A, do primeiro elo, produzia, após T segundos (Estudo 1) ou em uma dada probabilidade P (Estudo 2), o acesso a um novo elo de escolha entre os componentes R1 com reforço menor imediato (Estudo 1) ou reforço menor e mais provável (Estudo 2) versus R2 com reforço maior atrasado (Estudo 1) ou reforço maior e menos provável (Estudo 2). Ainda no primeiro elo, caso o componente B fosse escolhido, após T segundos (Estudo 1) ou uma dada probabilidade P (Estudo 2), havia um segundo elo em que apenas um componente, o R2' com reforço maior atrasado (Estudo 1) ou maior e menos provável (Estudo 2), estava presente. Como resultado, primeiramente os participantes passaram por condições de seleção em que maior magnitude deveria ser preferida sobre menor magnitude (para ambos os estudos); menor atraso deveria ser preferido sobre maior atraso (Estudo 1) e maior probabilidade deveria ser preferida sobre menor probabilidade (Estudo 2); menor magnitude e menor atraso deveriam ser preferidos sobre maior magnitude e maior atraso (Estudo 1) e menor magnitude e maior probabilidade deveriam ser preferidos sobre maior magnitude e menor probabilidade (Estudo 2). Depois, os participantes de ambos os estudos passaram por condições em que a reversão da preferência para a alternativa com reforço maior atrasado (Estudo 1) e reforço maior e menos provável (Estudo 2) foi avaliada. No Estudo 1, a variável tempo entre os elos (T) foi manipulada, envolvendo 7.5 e 15 segundos. Como resultado, os dados revelaram que a reversão aconteceu para todos os três participantes do Estudo 1, sendo que, apenas para o participante P1, tal reversão já ocorreu com o tempo (T) entre os elos de 7.5 segundos. Além disso, para dois dos participantes (P1 e P3) os maiores percentuais de escolha, no primeiro elo, foram no componente B. No Estudo 2, a reversão da preferência foi avaliada quando a probabilidade (P) entre os elos era de 17%. O dado indica que a reversão ocorreu, no sentido de que a maior parte das escolhas foi da alternativa com reforço maior e menos provável para todos os três participantes (P5, P6 e P7). Apenas para um desses participantes (P6) o componente B do primeiro elo foi o mais escolhido em dois blocos de tentativas. Ainda que esses dados sugiram relações com os que foram obtidos no Estudo 1, com a sugestão de que atraso e probabilidade do reforço apresentariam efeitos semelhantes sobre as escolhas em esquemas concorrentes encadeados, houve diferenças nas taxas de reforços entre os estudos, o que dificulta a comparação. O fato de a probabilidade de passagem para o segundo elo ter sido muito baixa (17%) limitou o número de tentativas em que os participantes tinham a chance de responder no segundo elo do Estudo 2. Consequentemente, o acesso aos reforçadores aconteciam em poucas ocasiões. Os Estudos 3 e 4 envolveram tentativas de escolha entre esquemas concorrentes simples, com manipulação de magnitude e atraso do reforço (Estudo 3) e magnitude e probabilidade do reforço (Estudo 4). Após condições de seleção semelhantes às dos estudos anteriores, os participantes passaram por uma condição com esquemas FR / FR concorrentes (com razão podendo variar de 10 a 80), em que a reversão da preferência foi avaliada. Os dados indicaram que a reversão ocorreu com todos os participantes do Estudo 3 (P7, P8 e P9) com maior preferência do componente com reforço maior atrasado e aconteceu com dois participantes do Estudo 4 (P11 e P12). Esses dados sugerem semelhanças entre o atraso e probabilidade do reforço em esquemas concorrentes simples. Em ambos os Estudos foram conduzidas, posteriormente, condições (CRF, SigFR e FI) em que se avaliou se o padrão de respostas gerado pela condição com FR seria modificado, com maior escolha da outra alternativa com reforço menor imediato (Estudo 3) ou reforço menor e mais provável (Estudo 4). Os dados revelaram que a mudança de padrão ocorreu apenas para dois dos participantes do Estudo 4 (P11 e P12) reforçando relações com os dados de um estudo conduzido anteriormente com pombos

There is disagreement among clicker trainers on whether or not food should be delivered every time the clicker (conditioned reinforcer) is used. However, presenting a conditioned reinforcer without food can weaken the strength of the conditioned reinforcer and also disrupt its discriminative stimulus function. A within subjects reversal design was used with 2 dogs to compare the behavioral effects of continuous pairings (C+F condition) vs. intermittent pairings (C+C+F condition) of the clicker with food. Results show that the C+C+F condition affects the frequency, accuracy, topography, and intensity of the behavior, and increases noncompliance and other unwanted behaviors. This study adds to the literature by evaluating the effects of conditioned reinforcement in an applied setting using discrete trials without undergoing extinction.

Stimulus preference assessments have determined high and low preferred items that increase the rate of frequency of responding for various skills. Within applied settings, high preferred items may not attain the same reinforcing value across tasks which might decrease responding. The preference of the task might have an effect on reinforcer efficacy that is being presented. The purpose of the current study is to evaluate changes in reinforcer efficacy as a function of preference for the task. Three children diagnosed with ASD participated in the study. HP/LP items and HP/LP tasks were identified through paired-choice assessments, and each item was presented as a consequence for each task in a counterbalanced multi-element format. Results indicated that preference for the task had little effect of the rate of responding across items.

Nos estudos do desamparo aprendido em humanos os resultados experimentais tem sido inconsistentes. Isso provavelmente devido a ocorrencia, na sessao de incontrolabilidade, entre outras variaveis, de contiguidades sistematicas entre o termino do estimulo aversivo e a resposta imediatamente precedente, mimetizando uma condicao de controle, embora acidental. Com o objetivo geral de estabelecer um procedimento que permitisse controle experimental suficiente para que fosse analisado o efeito de uma historia de incontrolabilidade sobre a aprendizagem de uma nova resposta operante em sujeitos humanos, bem como a prevencao (imunizacao) desse efeito, foram realizados tres experimentos. O primeiro deles demonstrou o controle operante sob tres contingencias de reforcamento negativo (sequencias variaveis, labirinto e discriminacao de formas geometricas), o que permitiu verificar o efeito da ausencia de controle sobre uma nova aprendizagem operante (Experimento 2 desamparo aprendido) e o efeito da ausencia de controle, apos historia de controle, sobre uma nova aprendizagem operante (Experimento 3 imunizacao). No Experimento 2, dois grupos de participantes foram expostos a sons aversivos (Grupos C e I) e um nao foi manipulado (Grupo N). Para os participantes do Grupo C, a interrupcao de um som agudo era contingente a emissao de sequencias variaveis; para os participantes do Grupo I, a duracao do som era independente das respostas emitidas. Os sujeitos do Grupo Incontrolavel foram divididos em dois subgrupos de acordo com a presenca ou a ausencia de indicacoes na tela (Ip e I). Na sessao de incontrolabilidade foram manipuladas algumas variaveis a fim de evitar a selecao acidental da resposta mensurada (duracao do estimulo; numero de tentativas; custo da resposta e instrucao inicial). Apos essa fase, todos os participantes foram submetidos a uma contingencia de resolucao de um labirinto associado a um som. No Experimento 3, um Grupo Precontrole (P) foi acrescido a triade do Experimento 2. A contingencia de fuga discriminação foi realizada na fase pre-tratamento sendo associada a um som. Na fase de teste os participantes dos Grupos C, N e P apresentaram menor latencia e maior numero de respostas corretas em comparacao aos grupos incontrolaveis. Entre esses ultimos, foi verificada uma correlacao negativa entre a frequencia de contiguidades no tratamento e o desempenho no teste. Os participantes do Grupo I apresentaram baixa frequencia de contiguidades no tratamento e latencias e falhas mais elevadas no teste; os do Grupo Ip mostraram padrao intermediario. Esses resultados replicam o desamparo aprendido e a imunizacao desse efeito em humanos, sugerindo que os pocedimentos estabelecidos foram adequados para o estudo desses dois efeitos e demonstram o papel da selecao acidental, durante a sessao de incontrolabilidade, como impeditivo da verificacao do efeito no teste (Grupo Ip). O papel das indicacoes na tela, os parametros utilizados e a presenca de contiguidades sistematicas foram discutidos / The results of learned helplessness studies with humans have been inconsistent. This is probably due to the systematic contiguity between the end of the aversive stimulus and the immediately preceding response during the uncontrollability session, which mimics an accidental control condition. Three experiments were conducted to establish a procedure with adequate experimental control to analyze the effects of an uncontrollability history upon learning of a new operant response in humans, as well as the prevention (immunization) of this effect. The first experiment demonstrated operant control under three negative reinforcement contingencies (variable sequences, maze, and discrimination of geometric forms), which allowed verifying the effect of the absence of control upon learning of a new operant response (Experiment 2 learned helplessness) and the effect of the absence of control, after a history of controllability, upon learning of a new operant response (Experiment 3 immunization). During the uncontrollability session, a number of variables were manipulated to avoid the accidental selection of the response being measured (duration of the stimulus, number of trials, response cost, and initial instructions). In Experiment 2, two groups were exposed to aversive tones (groups C and U) and one group was not (group N). For group C, the interruption of a high-pitch tone was contingent on the emission of variable sequences; for group U, the duration of the tone was response independent. Group U was further divided into two subgroups, according to the presence or absence of a hint on the screen (Up and U). After this manipulation, all participants had to solve a maze that was presented along with a tone. In Experiment 3, a pre-control group (P) was added to the ones in Experiment 2. The escape contingency for discriminating geometric forms was presented in the pre-treatment phase along with a tone. The results of the test phase indicated shorter latencies and a greater number of responses for groups C, N, and P, in comparison to the uncontrollable groups. For the latter groups, there was a negative correlation between the frequency of contiguities in the treatment phase and performance during the test phase. There was a low frequency of contiguities during treatment, and longer latencies and more errors during the test for Group U; an intermediate pattern was observed for Group Up. These results replicate the learned helplessness and immunization effects in humans, and suggest that this procedure is adequate to study these phenomena. The results also indicate that accidental selection during the uncontrollability session may eliminate the learned helplessness effect during the test (Group Up). The effects of the hints on the screen, the schedule parameters, and the presence of systematic contiguities are further discussed