Made available in DSpace on 2016-04-29T13:17:34Z (GMT). No. of bitstreams: 1 Ana Carolina Carneiro de Lima Cesarino.pdf: 495328 bytes, checksum: b1c91676469101ed2f6e1a1eb19876ec (MD5) Previous issue date: 2011-05-19 / Based on the literature of that age would be an important variable to be considered in studies of self-control, the aim of this study was to investigate how variables such as delay and magnitude of reinforcement, the presence of the reinforcer, the presence of distractions, with the consequence contingency wait, kind of consequence and likelihood of obtaining it influenced the choice by the response of self-control in children of different ages (2 years and 4 months to 6 years and 4 months). The response of self-control is defined in this study as the delayed reinforcer and the choice of greater magnitude. In the first experimental condition manipulated the age of the children so they could observe how was the choice by the reinforcer (smaller or larger, immediate and delayed) in each age group as well as observing how children of different ages behave in the face of waiting for the reinforcer of greater magnitude. In a second experimental condition a child (2 years and 4 months to 3 years and 10 months) and an older child (4 years and 1 month to 6 years and 4 months) were placed in a condition with the dual purpose of verifying whether a children represent a model for other modifying the choice of reinforcer delivered in the first experimental condition / Partindo-se da literatura de que a idade seria uma variável importante a ser considerada em estudos de autocontrole, o objetivo deste estudo foi o de investigar como variáveis como atraso e magnitude do reforço, presença do reforçador, presença de distrações, contingência da consequência com a espera, tipo de consequência e probabilidade de obtê-la influenciavam a escolha pela resposta de autocontrole em crianças de diferentes faixas etárias (de 2 anos e 4 meses a 6 anos e 4 meses). A resposta de autocontrole é definida no presente estudo como a escolha pelo reforçador atrasado e de maior magnitude. Numa primeira condição experimental manipulou-se a idade das crianças para que fosse possível observar como se dava a escolha pelo reforçador (menor e imediato ou maior e atrasado) em cada faixa etária, assim como observar como as crianças de diferentes idades se comportavam diante da espera pelo reforçador de maior magnitude. Numa segunda condição experimental uma criança menor (2 anos e 4 meses a 3 anos e 10 meses) e uma criança maior (4 anos e 1 mês a 6 anos e 4 meses) foram colocadas numa condição em dupla com o objetivo de verificar se uma criança representaria um modelo para a outra modificando a escolha do reforçador feita na primeira condição experimental

Salzinger (1998) define o comportamento verbal como um operante sujeito às conseqüências e discute que o comportamento verbal é parte de uma cadeia de respostas verbais e não verbais, públicas e encobertas, estando intimamente envolvido no manejo de outros comportamentos às vezes como causa, agindo como estímulo discriminativo e outras vezes apresentando o papel de efeito. Nesta encadeamento verbal, é fundamental estudar o papel das regras como estímulos verbais que descrevem contingências de reforçamento de forma completa ou parcial e conseqüências, e controlam a probabilidade de uma resposta. O presente estudo teve como objetivo investigar o efeito de variáveis verbais antecedentes com e sem autoclíticos, conseqüentes com autoclíticos e conseqüentes não verbais, para a instalação e manutenção do comportamento de escolha de alimentos variados para o café da manhã, considerando os diferentes grupos alimentares. Para isto, vinte crianças com faixa etária entre 10 e 12 anos foram organizadas igualmente em cinco Experimentos com arranjos diferentes quanto ao uso de variáveis verbais e não verbais. Na mesa de escolha de alimentos, havia quatro alimentos representantes dos carboidratos, dois das gorduras e quatro das proteínas e era considerada como escolha variada a resposta de escolher ao menos dois representantes dos carboidratos e proteínas e um das gorduras. Foram testadas ao todo dez diferentes variáveis nesse estudo, sendo nove delas verbais e uma não verbal, entre antecedentes e conseqüentes, distribuídas entre os Experimentos de forma a se manter um equilíbrio do número de fases em cada um deles. Houve variáveis antecedentes com variados graus de descrição da resposta que a criança deveria desempenhar, cada uma com autoclíticos diferentes, variáveis aplicadas individualmente e em grupo e uma variável de controle aversivo. Em alguns Experimentos procurou-se inverter as fases com emprego de variável antecedente com as fases que empregaram variável conseqüente, para se estabelecer uma comparação quanto à eficácia das mesmas na instalação e manutenção do comportamento de escolha variada. Os resultados principais indicam maior controle verbal das variáveis verbais conseqüentes com autoclíticos e das variáveis antecedentes com autoclíticos específicos e com descrição da resposta bem detalhada que aumenta a discriminabilidade dos estímulos relacionados à resposta e a probabilidade do fazer. Além da avaliação de que componentes da variável verbal podem melhor funcionar no controle do comportamento não verbal, no estudo fica evidente o importante papel das variáveis sociais na efetividade do controle verbal. Identificou-se especialmente no Experimento 5 que o controle verbal é maior em grupo, tanto no que se refere à mudança de comportamento de todos os participantes, como à manutenção da mesma após a retirada do controle verbal. As discussões gerais sobre os resultados mostram que o comportamento de escolha de alimentos parece ser fortemente instalado ao longo da história, de modo que sua alteração requer variáveis verbais tanto antecedentes como conseqüentes bastante específicas / Salzinger (1998) defines verbal behavior as an operant subject to consequences and argues that verbal behavior is part of a chain of verbal and nonverbal, overt or covert responses, being closely involved in managing other behaviors sometimes as \"cause\", acting as a discriminative stimulus, and other times playing an effect role. In this verbal enchainment, it is of fundamental importance to study the role of rules as verbal stimuli which describe reinforcing contingencies in a complete or partial manner and consequences, and control the likelihood of a response. The objective of this paper was to investigate the effect of antecedent verbal variables with and without autoclytics, consequents with autoclytics and nonverbal consequents, on the onset and maintenance of the behavior to choose varied foods for breakfast, considering the different food groups. To this end, twenty children aged between 10 and 12 were equally divided into five experiments with different arrangements as to the use of verbal and nonverbal variants. On the food choice table, there were four types of foods representing carbohydrates, two for fats and four for proteins, with a varied choice being considered as the response to choose at least two types of carbohydrates and proteins and one of fats. In all, ten different variables were tested in this study, with nine of them being verbal and one nonverbal, between antecedents and consequents, distributed among the experiments so as to maintain a balance of the number of phases in each one of them. There were antecedent variables with various degrees of description of the response the child was supposed to perform, each with different autoclytics, individually- and groupapplied variables and an aversive control variable. In some experiments we tried to reverse the phases using an antecedent variable with the phases which used a consequent variable, in order to establish a comparison as to their effectiveness in the onset and maintenance of the varied choice behavior. The main results indicate greater verbal control of consequent verbal variables with autoclytics and of antecedent variables with specific autoclytics and with detailed description of the response, which increases discriminability of the response-related stimuli and the likelihood of performing it. In addition to the assessment that components of the verbal variable may work better in controlling nonverbal behavior, the study evidences the important role played by social variables in the effectiveness of verbal control. It was identified, especially in experiment 5, that verbal control is higher in group, both regarding the change of behavior by all participants and its maintenance after verbal control was removed. General discussions on the results show that the food choice behavior seems to have been strongly settled along history, so that its alteration requires very specific verbal variables both antecedent and consequent

Diss. (sammanfattning)--Göteborg : University, 2002. / Härtill 4 uppsatser.

Submitted by admin tede (tede@pucgoias.edu.br) on 2018-11-19T17:28:43Z No. of bitstreams: 1 CARLA DE OLIVEIRA JARDIM.pdf: 838398 bytes, checksum: edc6fcacf736fb424d6ed3cf2e73a489 (MD5) / Made available in DSpace on 2018-11-19T17:28:43Z (GMT). No. of bitstreams: 1 CARLA DE OLIVEIRA JARDIM.pdf: 838398 bytes, checksum: edc6fcacf736fb424d6ed3cf2e73a489 (MD5) Previous issue date: 2018-08-09 / The objective of the following study was to evaluate the control exerted by the antecedent and consequent events of behavioral excesses and deficits from 2 diagnosed participants with class III obesity, also known morbid obesity. The objective also included the treatment of the behavior utilizing a self-control program. In order to evaluate the behavior, it was implemented indirect functional assessment using interviews and functional assessment direct observation of the participants during different moments throughout their daily routine. In order to control the procedure during the self-control sessions, it was used reversal- replication (ABAB) design, followed by follow-up within 30 days. The results indicated high occurrences of the behavioral deficits and excesses during the baseline phase and significant reductions during the intervention phase, such as gradual weight-loss for both participants. These reductions were maintained during the follow-up. These results demonstrated the importance of functional assessment for the efficiency of the self-control program. Based on these results, it is justified the implement of a self-control program in studies which required behavioral modifications for obese individuals in many classes, including morbid obesity. / O presente estudo teve como objetivo avaliar o controle exercido pelos eventos antecedentes e consequentes dos excessos e déficits comportamentais de duas participantes diagnosticadas com o grau III de obesidade, também descrita como mórbida. Objetivou-se também tratar estes tipos de comportamentos com o uso de um programa de autocontrole. Para avaliar os comportamentos foi empregada a avaliação funcional indireta com o uso de entrevistas e a avaliação funcional direta por meio de observação dos comportamentos das participantes em diferentes momentos de suas rotinas. Para as sessões do autocontrole foi usado o delineamento de reversão-replicação do tipo ABAB, seguido de follow-up de 30 dias. Os resultados apontaram altas ocorrências dos excessos e déficits comportamentais durante a fase de linha de base e importantes reduções destes comportamentos durante a fase de intervenção, bem como a perda de peso gradual de ambas as participantes, reduções estas que se mantiveram no follow-up. Estes resultados demonstram a importância da avaliação funcional para a eficácia do programa de intervenção. Em função destes resultados, justifica-se o emprego de um programa de autocontrole em estudos que exigem mudança comportamental para indivíduos obesos em diversos graus, inclusive a obesidade mórbida.

O comportamento de escolha é entendido como a seleção de uma entre duas ou mais alternativas disponíveis, diferente da preferência, que está relacionada ao tempo despendido respondendo a uma dessas alternativas. Em pesquisas com não humanos, observa-se que os sujeitos escolhem com maior frequência as alternativas nas quais o reforço estará disponível de forma imediata, em pequena quantidade, em comparação com a alternativa na qual o reforço estará disponível somente depois que o animal esperar um tempo determinado (atraso), mas em maior quantidade. Apesar da literatura apresentar dados sobre a influência da restrição alimentar e do sexo do animal em tarefas de aprendizagem, é importante aprofundar a investigação desses aspectos em tarefas de escolha. O objetivo desta pesquisa foi comparar o desempenho de ratos Sprague Dawley (machos e fêmeas) com história de restrição alimentar e ratos controle (com comida ad libitum), em uma tarefa de escolha, em que as alternativas variavam em relação ao atraso para ter acesso à comida e à quantidade de comida disponível. Foram utilizados 24 ratos (12 machos), de linhagem Sprague-Dawley, divididos em dois grupos. O Grupo Controle (C) recebeu dieta ad lib., enquanto o Grupo Restrição (R) teve sua dieta restrita a 80% da dieta do grupo controle. Aos 70 dias de idade, houve uma subdivisão dos grupos: metade dos animais do Grupo C formou o Grupo Controle-Restrito (CR 80% da dieta), e a outra metade o Controle-Controle (CC 100% da dieta). No Grupo R, metade dos animais formou o Grupo Restrito-Controle (RC 100% da dieta) e a outra metade, o Grupo Restrito-Restrito (RR 80% da dieta). Na Etapa 1 os animais exploravam labirinto em U em uma sessão de 10 tentativas. Na Etapa 2 foram realizadas 10 sessões de 16 tentativas de escolha forçada, sendo oito no braço direito, onde havia seis pelotas de ração disponíveis após atraso de 15 s (alternativa LL), e oito no braço esquerdo, com três pelotas de ração disponíveis sem atraso (alternativa SS). Na Etapa 3, foram conduzidas 45 sessões com 30 tentativas (10 forçadas e 20 livres), para verificar o padrão de escolha dos animais dos diferentes grupos em função da disponibilidade de reforço em cada alternativa, do atraso em uma das alternativas e do tempo inicial de espera (tempo T). Os animais de todos os grupos apresentaram preferência pela alternativa SS, independente do sexo ou da dieta. Ao comparar a porcentagem de escolhas dos grupos com relação às dietas foram verificadas diferenças no padrão e nas latências médias de escolha. O grupo RR apresentou latências médias de escolha significativamente inferiores às do grupo CC e um estabelecimento mais rápido de preferência pela alternativa SS que o grupo CC. Apesar de não terem sido encontradas diferenças significativas entre machos e fêmeas nos parâmetros analisados (possivelmente em função do n amostral), verificou-se que fêmeas apresentaram latências menores que machos em todos os grupos, além de porcentagens de escolha pela alternativa SS maiores que os machos. São discutidas hipóteses sobre a influência da dieta e da quantidade de alimento disponível em cada alternativa sobre as escolhas dos grupos. Essas hipóteses são também relacionadas a aspectos evolutivos, referentes às funções desempenhadas por machos e fêmeas na natureza. / The behavior of choice is understood as the selection of between two or more alternatives available, different from the preference, which is related to the time spent by responding to one of these alternatives. In researches with non-human animals, it is observed that the subjects choose more frequently the alternatives on which the reinforcement will be available immediately, in small quantity, in comparison with the alternative in which the reinforcement is available only after the animal expects a certain time (delay), but in greater quantity. Although literature present data on the influence of food restriction and the sex of the animal in tasks of learning, it is important to deepen the investigation of these aspects in tasks of choice. The objective of this research was to compare the performance of rats Sprague Dawley (male and female) with a history of food restriction and control rats (with food ad libitum), in a task of choice, in that the alternatives varied in relation to the waiting time for access to food and the quantity of food available. 24 albino rats (12 males), from Sprague-Dawley lineage was used, divided in two groups. The Control Group (C) received diet ad lib., while the group restriction (R) had their diet restricted to 80% of the diet of the control group. At 70 days of age, there was a subdivision of the groups: half of the animals from group C formed the Group Controle-Restrito (CR - 80% of the diet), and the other half the Controle-Controle (CC - 100% of the diet). In Group R, half of the animals formed the Group Restrito-Controle (RC - 100% of the diet) and the other half, the Restrito-Restrito group (RR - 80% of the diet). In Step 1 the animals explored the labyrinth in U in a session of 10 attempts. In Step 2, there were 10 sessions of 16 attempts of forced choice, being 8 in the right arm, where there were six pellets of ration available after delay of 15 s, and eight in the left arm with three pellets of rations without delay. In Step 3, 45 sessions were conducted with 30 attempts (10 forced and 20 free), tarry check the default choice of animals of different groups in relation to the availability of strengthening in each alternative, the delay in one of the alternatives and the initial time wait time (T). Animals of all groups have preference for the SS alternative, independently of sex or diet. Differences were verified in the pattern and average latencies of choices in comparing the percentage of choices of the groups in relation to the diets. The RR group presented significantly lower average latency in comparison to group CC and a faster preference was established for alternative SS than group CC. Even having no significant differences been found between males and females in the scope studied (possibly due to then sampling), it was verified that females present lower latencies that males in all groups, besides the higher percentages for choosing alternative SS in males. Hypotheses are discussed on the influence of the diet and the quantity of food available in each alternative over the group choices. These hypotheses are also related to evolutionary aspects, referent to functions performed by males and females in nature.

The establishment of intermediate care facilities in British Columbia, as well as the establishment of similar facilities throughout the rest of Canada, was and still is a well-intentioned approach to meet the long term care needs of the elderly. The practices and procedures adopted by long term care facilities, however, tend to inhibit the personal autonomy of residents (Thomasma, 1985). Specifically, a facility's practices and procedures tend to inhibit residents' latitude of choice regarding daily living activities. Residents' latitude of choice may also be lessened when nurses implement well-intentioned helping interventions based on their own motivations and goals, rather than those of elderly residents. Latitude of choice measures the extent to which an individual's perceived degree of choice includes activities of importance to him/her. At present, there is limited research addressing both resident and staff perceptions regarding the autonomy (freedom of choice) of residents, particularly in relation to their daily activities. Accordingly, this study's purpose was to determine the institutionalized elderly residents' and their caregivers' perceptions of residents' latitude of choice regarding activities of daily living. From determining these specific staff and resident perceptions, significant differences were isolated. This study was conducted in two intermediate care facilities located in a large city within the province of B.C. The data collection instruments in this study included selected questions from Hulicka et al.'s (1975) revised Importance, Locus and Range of Activities Checklist, as well as a demographic data sheet developed by the researcher. Forty-five intermediate care 1 residents and forty-five nurses (Registered Nurses, Licensed Practical Nurses and Nurses' Aides) completed the study questionnaire and the demographic data sheet. The researcher studied the residents' and staff's responses to the Importance, Locus and Range of Activities Checklist by using non-parametric techniques for statistical analysis. The researcher used these techniques to determine the existence and location of differences in perceptions among the residents and staff. Significant differences exist in residents' and staff's perceptions when each group's importance ratings are combined with choice ratings. Isolation of the above importance and choice components for individual analyses indicate that the residents and staff had significantly different response patterns regarding a) the importance residents attach to daily living activities and b) the degree of choice residents associate with daily living activities. The above findings indicated that residents' latitude of choice may not be realized to a greater extent if the staff do not attach a degree of importance to a particular activity(ies) similar to that attached by the residents. Residents' latitude of choice may not be recognized to a greater extent if staff do not perceive that residents associate "some" or "no choice" with an activity of particular importance to them. / Applied Science, Faculty of / Nursing, School of / Graduate

Pedestrian walking and choice behavior presented was first studied by Fruin in 1971, and since then a lot of research have been carried out in order to understand how humans move and what does make them make choices and obtain certain patterns. In relation to pedestrians, a significant bottleneck inside public stations evaluated by research are the level-change facilities, as Stair Walks and Escalators. The aim of this research is studying how pedestrian behave in the vicinity to stairways and escalators, and how does that affect pedestrian choice, speed and acceleration when choosing one of the two facilities. Also, with a need for more data on pedestrian traffic, further data collection is a big requirement to analyze their behavior and use as tools in future measures. At last, how to optimize the movement of pedestrians in relation to level changes, considering the effects of the movements observed. Two case studies were analysed, Stockholm Central Station and Uppsala Central Station.The study compares data collection methods, tracking methods and previous studies to better fit the scope of this research. The data is backed up from previous research and explains which method better fitted the options available. As a result, video data collection was chosen to collect the data, a semi-automatic tracking software called T-analyst was used to extract speed, trajectories and acceleration from the videos, and microsimulation modelling from VISSIM further investigated different design options to optimize the overall performance and improve travel time in the same area. The analysis found out that there was a possibility to increase the overall performance of the location in higher flow levels, where the most significant queues could be seen, since there was the possibility to achieve higher speeds by modifying the width and position of the stair walks, which allow for a smaller queue in both directions.

The current study examined the impact that components of Social Cognitive Career Theory (SCCT) have on choice behavior and academic performance in African American or Black, undergraduate students. SCCT is a highly valued and researched theory, but few studies examine the impact that SCCT components have on choice behavior and academic performance in Black college students. This study focused on evaluating SCCT components’ relevance to variables that have been shown to predict later objective career success. This is important because African Americans tend to have significantly lower paying and less prestigious jobs, as well as attain lower levels of education than most other racial populations in the United States. However, there is a paucity of current career development and attainment literature specific to the African American undergraduate population. In an effort to promote understanding of within group differences in SCCT variables that can contribute to educational and career success, 247 African American undergraduates were recruited to participate in this study. The participants completed online questionnaires regarding demographic information, self-efficacy, contextual barriers, contextual supports, choice goals, and choice behavior. Participants also gave permission for researchers to access grades. Findings indicate that academic coping self-efficacy, contextual barriers, and contextual supports may be particularly important to academic choice behavior in African American college students. Further, choice behavior appears to be important to grade point average. Implications, limitations, and recommendations for future research associated with this study’s findings are discussed.

Pharmakodiagnostische Tests eröffnen die Möglichkeit, Krebstherapien individueller auf den Patienten zugeschnitten zu verschreiben. Die vorliegende Dissertation widmet sich deshalb der Frage, wie diese Gruppen in Deutschland sowie den USA in Bezug auf diese Tests Entscheidungen treffen. Alle im Rahmen dieser Arbeit durchgeführten Studien waren unterteilt in eine Vorstudie und eine Hauptsstudie. Die Ergebnisse der Vorstudie wurden im Rahmen der Hauptstudie zur Entwicklung eines Fall-Vignetten Fragebogens benutzt,um die Verwendung von kompensatorischen und nicht-kompensatorischen Entscheidungsstrategien zu untersuchen. Mit Studie I wurde gezeigt, dass sowohl deutsche als auch amerikanische Onkologen eine hohe Bereitschaft haben, solche Tests anzuwenden. Die entsprechenden Entscheidungen wurden am besten durch ein kompensatorisches Modell (Franklin’s Rule)vorhergesagt. Eine Leitlinien-Empfehlung führte nahezu immer zu einer Test-Entscheidung. Verschiedene Bedingungen machten eine Entscheidung für nicht-empfohlene Tests jedoch wahrscheinlicher. Studie II zeigte, dass Pathologen nur zu einem beschränkten Ausmaß bereit waren, von dem etablierten Test-Standard für neuartige Test-Prozeduren abzuweichen. Die Entscheidungsstrategie beider Gruppen wurde gleich gut durch die jeweiligen kompensatorischen Modelle (Franklin’s und Dawes’ Rule) sowie durch das nicht-kompensatorische Modell (Take The Best) vorhergesagt. Für die mit Studie III untersuchten Krebspatienten zeigte sich, dass ein nicht-kompensatorisches Modell (Matching Heuristic) die besten Entscheidungs-Vorhersagen machte.Während die Entscheidungen der US Patienten jedoch maßgeblich von einer Arzt-Empfehlung geleitet waren, fand sich dies nicht für die deutschen Patienten. Die sich aus den Befunden ergebenden Implikationen für die hier untersuchten Gruppen, für die mit der Leitlinien-Entwicklung beauftragten Autoritäten als auch für das Gesundheitssystem im Allgemeinen wurden abschließend diskutiert. / Upcoming pharmacodiagnostic tests offer the opportunity to better tailor cancer treatment decisions to individual patient needs. However, they put oncologists, pathologists, and cancer patients in the position of having to deal with a new technology, which often comes with its own specific risks. Little is known about how these different groups will handle this situation. This thesis is a first effort to examine, within Germany and the USA, how the respective groups would deal with a decision on applying such a test to a cancer treatment decision. All accomplished studies were divided into an explorative pilot study and a main study. Results of the pilot study were used for the main study to develop a case vignette questionnaire in order to investigate compensatory and noncompensatory decision-making strategies.In Study I, it was found that both, German and US oncologists’ decision-making policies were best described by a compensatory model (Franklin’s rule). A recommendation of a test by guidelines triggered nearly always a choice for having the test, although under different conditions also choices for nonrecommended tests were likely. Study II found that pathologists were, to a rather small extent, prepared to opt for more sophisticated test alternatives, compared to standard procedures. For both samples, decision making was equally well-predicted by two compensatory models (Franklin’s rule and Dawes’ rule), as it was by a noncompensatory model (Take The Best.Study III focused on cancer patients. The German as well as the US patients’ decisions were best predicted by a noncompensatory model (Matching Heuristic), while for the US patients, the most impacting cue was the recommendation by an oncologist, what could not be found for the German sample.Several implications of these findings for the respective groups, for authorities in charge of developing guidelines, as well as for the health systems in general, are discussed.

A metacognição é processo conceituado como o julgamento que um organismo (humano ou não humano) faz sobre seu próprio saber ou não saber. Há relatos de pesquisas sobre esse processo com seres humanos e diversas espécies de não humanos. Poucos estudos, porém, discutem a ocorrência de metacognição em ratos, e os resultados são controversos, em função de questionamentos sobre os procedimentos experimentais empregados. Este estudo teve o objetivo de investigar o efeito da manipulação de diferentes proporções de reforço produzidas em duas alternativas, sendo uma probabilística e outra com reforçamento contínuo, sobre o desempenho de ratos em uma tarefa de discriminação de diferentes durações de estímulos sonoros. O procedimento empregado é uma adaptação do utilizado por Foote e Crystal (2007), que investigou a ocorrência de metacognição em ratos. Foram utilizados cinco ratos machos, da linhagem Wistar (Rattus norvegicus) mantidos a 80% de seu peso ad libitum. O aparato utilizado foi um labirinto em Ey. O procedimento consistiu de quatro fases: 1) Treino exploratório no braço em Y, no qual o animal foi exposto a alternativas que continham seis pelotas de ração; 2) Treino de discriminação de estímulos sonoros, no qual foram treinadas duas discriminações condicionais com duas durações de estímulo sonoro, uma curta (2s), e uma longa (8s), cada uma correlacionada com a escolha de uma das portas do braço em Y; 3) Treino exploratório no braço em I, no qual os animais foram expostos a uma alternativa livre, que continha três pelotas de ração; e 4) Fase de Teste, na qual foram apresentadas diferentes durações de som (2.00, 2.44, 2.97, 3.62, 4.42, 5.38, 6.56 e 8.00s), a partir das quais o animal poderia escolher entre o braço em Y (fazer o teste), e receber seis pelotas de ração caso escolhesse a porta correta (correlacionada à duração curta ou longa), ou escolher a alternativa de recusa do teste, produzindo, com certeza, a quantidade de ração estabelecida pela condição em vigor. Foi analisada a porcentagem de escolhas realizadas pelos animais nos braços Y e I em cada condição, assim como a relação entre a porcentagem de acertos e erros nos testes e recusa, para cada duração de som. Todos os sujeitos atingiram o critério de aprendizagem estabelecido na fase de treino. Na fase de testes, observou-se que o som deixou de exercer controle sobre a resposta de escolha de todos os animais. À medida que a proporção de reforço variou na alternativa de recusa, os animais alteraram o padrão de escolha, de propensão para aversão ao risco, de acordo com a condição em vigor. A escolha por uma alternativa não se mostrou sob controle da acurácia dos animais em discriminar as durações dos estímulos apresentados, mas sim da proporção e probabilidade do reforço em cada alternativa. Discute-se a necessidade de se recorrer ao conceito de metacognição para descrever o desempenho dos animais em tarefas como a empregada no presente estudo. / The metacognition process is known as the judgment that an organism (human or nonhuman) makes of its own knowing or not knowing. There are research reports on this process in humans and several nonhuman species. Few discuss the occurrence of metacognition in rats, though, and the results are controversial due to the questionings about the experimental procedures applied. The aim of this study was to investigate the effects in handling different reinforcement proportions in two alternatives, one being probabilistic and the other with continuous reinforcement, on the performance of rats in a task of discrimination of different sound stimuli duration. The applied procedure was adapted from that used by Foote and Crystal (2007), which investigated the occurrence of metacognition in rats. Five male Wistar rats (Rattus norvegicus) were used and maintained at 80% of their weight ad libitum. The apparatus used was an Ey-shaped maze. The procedure consisted of four phases: 1) exploratory training on the Y arm, in which the animal was exposed to alternatives containing six pellets of food; 2) training on sound stimuli discrimination, in which were trained two conditional discriminations with two different sound stimuli durations one short (2s) and one long (8s) each linked to the choice of one door from the Y arm; 3) exploratory training on the I arm, in which the animals were exposed to a free-choice alternative containing three pellets; and 4) test phase, in which were used different sound durations (2.00, 2.44, 2.97, 3.62, 4.42, 5.38, 6.56 and 8.00s), giving the animal the option of choosing between the Y arm (doing the test) and get six pellets of food if it chooses the correct door (according to the short or long duration), and the refusal of the test, producing, that way, an amount of food established by the current condition. The percentage of choices made by the animals on the Y and I arms in each condition was analyzed, as well as the relation between the percentage of successes and errors in tests and refusals for each sound duration. All the subjects achieved the learning criterion stated in the training phase. During the test phase it was noted that the sound ceased in exerting control over all the animals responses. As the reinforcement proportions varied in the refusal alternatives the animals altered the pattern of choice from risk-proneness to risk-aversion, according to the current condition. The choice for an alternative didnt show to be controlled by the animals accuracy in discriminating the stimuli durations presented, but by the proportion and probability of the reinforcement in each alternative. Its been discussed the need to resort to the concept of metacognition to describe the animals performance in tasks such as the one applied in the present study.