International service learning (ISL) has been integrated into engineering education and has become increasingly more popular in co-curricular experiences. While prior research investigates each of these avenues of ISL, we have not investigated how these experiences compare to one another in terms of student learning outcomes or understood these experiences from a national perspective. The purpose of this thesis is to address these gaps in existing literature and to provide a comprehensive, holistic perspective of ISL experiences ability to impact student learning on a national scale. To better understand student learning outcomes in engineering ethics, agency and identity and draw comparisons in student career choices, several survey instruments were used within a nationally-representative survey distributed to engineering seniors (n=1911) at four-year universities within the United States. Descriptive statistics were used to categorize he responses by type of ISL experience: capstone, work, or co-curricular. The survey instruments were used to measure the individual learning outcomes: engineering ethics contained 5 items, engineering identity contained 14 items, and engineering agency contained 12 original items. Each survey instrument was validated using an exploratory factor analysis (EFA) to determine the relevant factor groups for each construct. An ANOVA test or Kruskal Wallis, the non-parametric equivalent test, was used for each dataset depending on normal distribution of the data. Responses in engineering ethics showed a significantly higher score in students’ ethics understanding with ISL capstone (p< 0.001) and work experience (p<0.0001) and a medium effect size for both (Cohen’s d=0.3). Responses in engineering agency scores showed a significant difference with ISL capstone (p<0.05) and co-curricular experience (p<0.05) with a medium effect size (Cohen’s d=0.3). Additionally, responses to predicted career choice post-graduation showed a lower percentage of students anticipating leaving engineering from the 9% population rate to 6% for those with ISL capstone experience and 5% for those with ISL co-curricular experience. These results give reason to consider more frequent incorporation of ISL projects into engineering courses such as senior capstone design. / Master of Science / International service learning (ISL) is a way of learning that allows students to use their engineering skills to help others, while gaining experience in a global context. ISL projects allow students to interact with people around the world, gaining experience with cultural and social diversity while using and developing their engineering skills. ISL projects take many forms and have been used within engineering education in many ways. The three most common ISL experiences are integration into capstone courses, independent ISL work experience, and co-curricular programs such as Engineers Without Borders. Prior research has focused mainly on capstone and co-curricular ISL experiences. Research found ISL experiences beneficial for student learning, however prior research has not investigated how these experiences compare. Additionally, many studies are conducted within courses or programs which provides a limited general understanding. This study aims to provide more clarity between student learning by ISL experiences and provide a national perspective on the impacts of ISL experiences. The purpose of this study was to determine how effective ISL experiences are in improving student learning in engineering ethics, agency, identity, and retaining engineering students in the field after graduation. A survey with a total of 31 questions related to these topics (5 for engineering ethics, 12 for engineering agency and 14 for engineering identity) was nationally distributed to senior engineering students enrolled at four-year universities in the United States. The responses were categorized by student’s ISL experience (capstone, work, and co-curricular) and compared for each engineering topic. The data was analyzed statistically, and the survey questions were analyzed to ensure that they were measuring student learning as expected. The results showed that ISL capstone projects improved students’ understanding of engineering ethics, increased their sense of engineering agency, and led to a lower percentage of students who planned to leave the field of engineering after graduation. ISL work experiences improved ethics understanding for students but had little to no impact on engineering agency. Finally, ISL co-curricular experiences had little impact on engineering ethics understanding, but improved student’s engineering agency beliefs and led to a less students leaving the field. These results give reasons to consider integrating ISL experiences into engineering education more frequently to provide benefits to students.

Design thinking ability is vital for engineers who are tasked with solving society's toughest sustainable development challenges. Prior research identified that the percentage of design thinkers among freshmen engineering students is greater than the percentage among the general population. However, engineering education's lack of attention to fostering creative ability may cause the design thinking ability of senior engineering students to suffer. The research addressed in this thesis compares the design thinking ability of engineering students across age groups, and compares design thinking ability between the design disciplines of engineering and architecture. To draw design thinking comparisons between these groups, a survey with a nine item design thinking instrument was distributed nationally to freshmen engineering students (n= 2,158), senior engineering students (n= 1,893), and senior architecture students (n= 336). The survey instrument was validated by conducting confirmatory factor analysis on the senior engineering and senior architecture samples' data. The Analysis of Variance (ANOVA) test was utilized to statistically compare scores across sample groups. Both the freshmen engineering students (2.80) and senior architecture students (3.30) scored significantly higher on the design thinking scale than senior engineering students (2.59). These results have important implications for engineering educators as engineering education may contribute to a decrease in design thinking among senior engineering students. A lower design thinking score among seniors was consistent across all engineering sub-disciplines and should be of concern to engineering educators, since design thinking skills are critical for the development of engineering solutions to grand societal challenges. / Master of Science / Design thinking is a way of thinking about the design process which places the user at the center of the design. Thinking about design in this way is a vital ability for engineers and other design professionals to develop because it enables them to solve “wicked” problems like sustainable development challenges. Wicked problems are those which are difficult to solve due to the number of conflicting components involved. Prior research has found that design thinkers are more prevalent among engineering students in their first year of study than among students in other majors. However, engineering education does not attribute much attention to the development of creative ability which could cause the design thinking ability of engineering students in their final year of study to be worse than the ability of those in their first year, as well as worse than the ability of students who study other design disciplines like architecture. This study compared the design thinking abilities of engineering students in their final year of study to engineering students in their first year and to architecture students in their final year. The goal of making these comparisons was to explore if engineering education helps or hinders the development of design thinking. A survey with nine questions related to design thinking was distributed nationwide. The data from the survey was collected and statistically analyzed. The results showed that the design thinking ability of engineering students in their final year was significantly lower than the ability of first year engineering students and significantly lower than the ability of final year architecture students. A decrease in design thinking ability between freshmen and senior year must be addressed by engineering educators. The National Academy of Engineers and industry leaders are calling for the development of engineers who are design thinkers, and the results of this paper suggest that some changes may need to occur within the engineering education curriculum to accommodate this need.

Large public water utilities currently are required to take several 100 mL water samples every month in their distribution systems and to test these samples for the presence of total coliforms to comply with the Total Coliform Rule. How and where they take these samples is not specified. The Total Coliform Rule is currently undergoing review and revision. One possible revision is more specific rule language or guidance of where and when utilities take their monthly coliform water samples. This project considers various drinking water distribution system monitoring strategies for a large drinking water utility using simulations within an EPANET computer model of that utility's distribution system. A review of the literature and the use of best professional judgment help to inform the understanding of the primary causes of the occurrence of coliform bacteria in drinking water distribution systems. In this analysis, both contamination scenarios and coliform monitoring approaches are simulated in the EPANET computer model to better understand what types of contamination events might be detected by routine coliform monitoring and to what extent monitoring strategies affect observed results. In addition, statistical strengths of the various strategies and their respective results are considered in this project. Analysis of model output supports the assertion that water age may be a good factor to consider in designing a monitoring plan, especially if sampling cannot be conducted every day and that taking samples immediately after and in the vicinity of rapid changes in flow (e.g., during a firefighting incident) may help utility operators to better understand what associated risk, if any, exists to consumers of drinking water as a result of these flow conditions. / Master of Science

During vibration of engineering structures, fatigue cracks may exhibit repetitive crack open-close breathing like phenomenon. In this thesis, the concept of entropy is employed to quantify this bi-linearity/irregularity of the vibration response so as to evaluate crack severity. To increase the sensitivity of the entropy calculation to detect the damage severity, entropy is merged with wavelet transformation (WT). A cantilever beam with a breathing crack is studied to asses proposed crack identification method under two vibration conditions: sinusoidal and random excitations. Through numerical simulations and experimental testing, the breathing crack identification under sinusoidal excitation is studied first and proven to be effective. Then, the crack identification sensitivity under lower excitation frequencies is further improved by parametric optimization of sample entropy and WT. Finally, breathing crack identification under general random excitations are experimentally studied and realized using frequency response functions (FRFs) as an add-in tool with the proposed crack identification technique. / October 2016

This thesis overviews and discusses the issue of nonperforming loans in general and in China, and financial sector development from the beginning of Deng Xiaoping's reform era in 1978. The focus is put on the underlying institutional framework as it is found to be one of key contributing factors of NPLs in China. Utilizing a sample of 23 countries over the period 2000-2009, we estimate the impact of macroeconomic determinants on nonperforming loans. One of the regressors, output gap, is estimated via Kalman filtering technique based on the multivariate unobserved component (MUC) method. Consequently, out-of-sample method forecasts for five subgroups of countries, thus providing different benchmarks for China, are compared with official data. The conclusion argues the NPLs ratio to be understated in official statistics, especially towards the end of the series, which might be a sign of increasing macroeconomic instability in China.

A demonstração da formação de classes de equivalência é dificultada pela ausência de reforçamento durante os testes de relações emergentes que documentam suas propriedades, em particular quando se trata de sujeitos não-humanos e humanos com desenvolvimento atípico. O presente trabalho propõe uma alternativa metodológica para testar a formação de classes de equivalência sob condições de reforçamento diferencial. O primeiro estudo testou simetria e transitividade em humanos adultos verbalmente competentes com o propósito de avaliar o procedimento em condições favoráveis à demonstração da formação de classes de equivalência. O segundo estudo aplicou o procedimento na avaliação de simetria em pombos. Em termos gerais, os sujeitos foram treinados em uma linha de base de relações condicionais antes de serem submetidos a testes reforçados de simetria ou transitividade. Durante o teste de simetria, dois conjuntos de relações condicionais foram adicionalmente reforçados: um constituído das contrapartes simétricas de relações da linha de base, o outro de relações inéditas não simétricas formadas pela recombinação de estímulos da linha de base. Desempenhos mais precisos nas relações simétricas em comparação às relações inéditas sugeririam um controle condicional por simetria. A mesma estratégia foi empregada para avaliar transitividade. Em relação aos resultados, os participantes humanos responderam com acurácia superior nas relações simétricas e transitivas do que nas relações inéditas no transcorrer de cada teste. Esses achados demonstram a efetividade do procedimento em avaliar a emergência de relações que definem equivalência de estímulos. Os pombos, por sua vez, desempenharam ao nível do acaso tanto nas relações simétricas quanto nas relações inéditas em um primeiro teste envolvendo a metade dos estímulos da linha de base. Entretanto, depois que essas relações foram treinadas até alta acurácia, todos os sujeitos responderam com precisão superior nas relações simétricas durante um segundo teste envolvendo os estímulos restantes da linha de base. Esses resultados contrastam a maioria dos resultados de estudos anteriores com sujeitos não-verbais e sugerem que formação de classes de equivalência pode ser verificada em tais populações sob condições adequadas de treino e teste. / The lack of reinforcement in tests of emergent relations interferes with the demonstration of equivalence-class formation in nonhuman animals and humans with developmental disabilities. The present work proposes an alternative methodology to test equivalence-class formation under differential reinforcement conditions. The first study assessed symmetry and transitivity in verbally-able human adults in order to evaluate the proposed procedure. In the second study, such a procedure was applied to assess symmetry in pigeons. After subjects have been trained on the baseline conditional relations they were given either a symmetry or a transitivity reinforced test. During the symmetry test, two sets of conditional relations were additionally reinforced: symmetrical versions of the baseline relations and novel relations, formed by recombining stimuli from the baseline. Evidence for symmetry would be indicated by higher accuracies on the symmetrical than on the novel relations. Similar strategy was used to test transitivity. The results showed that human participants performed with higher levels of accuracy on the symmetrical and transitive relations than on the novel relations throughout each test. These founds indicate the efficacy of the procedure to test emergent relations that define stimulus equivalence. Pigeons, in turn, performed at chance-level in both symmetrical and novel relations in the first test involving half of the baseline stimuli. Nevertheless, after such relations have been trained to a high accuracy, all the pigeons matched at higher levels of accuracy on the symmetrical relations in the second test involving the remaining baseline stimuli. This result contrasts with the lack of symmetry reported in most of previous studies with nonverbal subjects and indicates that symmetry can emerge in such a population under adequate conditions of training and testing.

Entendendo que o estudo das topografias de controle de estímulo (TCEs) pode ser beneficiado em um procedimento de discriminação condicional para a investigação de controle complexo de estímulos, em especial na formação de classes de estímulos equivalentes, o presente estudo busca investigar essa questão diretamente, por meio de um software que executa o matching-to-sample (MTS) de uma maneira modificada. Tal modificação na tarefa de MTS consiste basicamente da introdução de respostas de observação (ROs) como um possível recurso para a descrição e a avaliação do estabelecimento de diferentes TCEs tanto ao longo do treino de discriminações condicionais como dos testes para verificar a formação de classes de estímulos equivalentes. Para tanto, foram planejados três experimentos. No Experimento 1, os objetivos foram a) investigar a ocorrência e seqüência de ROs e b) analisar a probabilidade do estabelecimento de diferentes TCEs (seleção e rejeição). Participaram três estudantes universitários. Na tarefa, MTS com atraso de 0s e três estímulos de comparação, estes e o estímulo modelo apresentavam-se inicialmente cobertos, tornando-se visíveis somente após a emissão de ROs. Todos os participantes apresentaram sucesso na formação de equivalência, com probabilidades de respostas de escolha ao S+ sob controle tanto da TCE seleção como da TCE rejeição, demonstrando que as ROs tornaram-se um recurso efetivo para esse tipo de investigação. No Experimento 2, foram apresentadas variações metodológicas com o objetivo de favorecer o estabelecimento de uma ou de outra TCE (seleção ou rejeição), durante o treino das relações condicionais e verificar os efeitos destas variações no desempenho obtido nos testes. Participaram seis estudantes universitários submetidos a uma condição na qual a observação ao S+ (três participantes) ou ao S- (três participantes) foi impedida em 70% das tentativas de treino. Os resultados indicaram que as restrições à observação de S+ produziram maior prejuízo à formação de equivalência do que as restrições as restrições à observação de S-, além de se evidenciar a relativa falta de coerência entre as TCEs planejadas e as estabelecidas pelos participantes. Para o Experimento 3, no qual participaram 12 estudantes universitários, o arranjo experimental programado durante a fase de treino foi: a) definir S+ a partir da primeira RO emitida como uma situação favorecedora do estabelecimento da TCE seleção (para três participantes, em 100% das tentativas e para outros três, em aproximadamente 80% das tentativas) ; e b) definir o S+ a partir da terceira RO como uma situação favorecedora do estabelecimento da TCE rejeição (em 100% das tentativas para três participantes e em, aproximadamente 80%, para outros três). Nos resultados, destacou-se o sucesso da formação de classes de estímulos equivalentes no desempenho apresentado por todos os participantes sob as condições 1ª/80% e 3ª/80% e por apenas um participante da condição 1ª/100%. Nos desempenhos bem-sucedidos nos testes, identificou-se o estabelecimento de ambas TCEs, especialmente sob as condições 3ª/80% (todos os participantes) ou, majoritariamente da TCE seleção (único participante da condição 1ª/100%). O conjunto geral dos dados permite discutir que o favorecimento a uma ou outra TCE pode alterar o treino de condicionalidade, pois o sucesso na formação de equivalência parece ser produto de uma provável simultaneidade das diferentes TCEs. Neste sentido, há que se investir ainda mais nas manipulações cujo foco seja o planejamento de diferentes favorecimentos. / Understanding that the study of stimulus control topographies (SCT\'s) may be benefited on a conditional discrimination procedure to investigate the complex control of stimuli, specially in the classes formation of equivalent stimuli, this study investigates this issue directly, through a software that executes the matching-to-sample task (MTS) in a modified way. This change in the task of MTS consists basically of responses to observing responses (OR\'s) as a possible resource for describing and evaluating the establishment of much different TSC\'s, both during the long training of conditional discrimination and during the testing to verify the classes training of equivalent stimuli. For this, three experiments were designed. In Experiment 1, the objectives were a) to investigate the occurrence and sequence of OR\'s and b) to analyze the establishment probability of different SCT\'s (selection and rejection). Three under-graduate students participated. In the task, MTS with delay of 0s and three stimuli for comparison, the model and the stimulus were initially covered up and became visible only after the OR\'s issuance. All participants had success in the equivalence formation, with probabilities of responses choice to S+ under control of both the SCT selection and the SCT rejection, demonstrating that the OR\'s have become an effective resource for such research. In Experiment 2, methodological changes were made with the objective of encouraging the establishment of either SCT (selection or rejection) during the conditional relations training and to see the effects of these variations in performance obtained in the tests. Six under-graduate students participated submitted to a condition in which the observation of S+ (three participants) or the S- (three participants) was prevented in 70% of attempts at training. The results indicated that the restrictions on the observation of S+ produced more injury to the restrictions equivalence formation than the ones on the observation of S-, in addition to demonstrating the relative lack of coherence between the SCT\'s planned and established by the participants. For Experiment 3, in which 12 under-graduate students participated, the experimental apparatus programmed during the training was: a) to define S+ from the first issued OR as a situation favoring the TSC selection establishment (for three participants, 100% of attempts and three others, in approximately 80% of attempts), and b) to set the S+ from the third RO as a situation favoring the TSC rejection establishment (in 100% of attempts to three participants and approximately 80%, other three). In the results, the classes formation success of equivalent stimuli in the performance shown by all participants under the conditions 1st / 3rd and 80% / 80% and by only one participant of the 1st condition / 100% stood out. In the successful performance in tests, the establishment of two SCT\'s, specially under conditions of 3 / 80% (all participants), or primarily of SCT selection (single participant of the 1st condition / 100%) was identified. The general data set allows us to discuss the bias that either SCT may change the conditionality practice, since the success in equivalence formation seems to be a likely simultaneity product of the different SCT\'s. Accordingly, it is necessary to invest more in the manipulations in which the focus is the different bias planning.

Introdução: O objetivo desse estudo é obter um melhor entendimento de como o controle motor é afetado em indivíduos com polineuropatia diabética (PND). A oscilação da força e da atividade eletromiográfica (EMG) durante contrações voluntárias isométricas têm sido estudados como um modelo simplificado dos mecanismos fisiológicos que estão por trás do controle do movimento. A análise dos padrões de recrutamento muscular dos membros inferiores obtidos pela EMG de alta densidade, juntamente com a análise dos dados de força relativos às articulações do joelho e do tornozelo, sob a ótica da análise da complexidade, contribui para o entendimento dos efeitos da doença no controle dos movimentos. Além disso, analisar a complexidade da força e da atividade muscular de indivíduos diabéticos com PND levando em conta o progresso da severidade da doença, desde os estágios subclínicos aos mais avançados, irá ajudar no entendimento de como as alterações neuromusculares vão se instalando no curso da doença. As hipóteses desse estudo foram: a PND altera a complexidade motora o que se reflete em um aumento na magnitude da variabilidade e em uma diminuição da estrutura da variabilidade nos dados de força e EMG; e essas alterações pioram com a severidade da doença. Métodos: Foram avaliados 10 sujeitos controles e 38 sujeitos diabéticos, classificados como ausentes, leves, moderados ou graves, em relação ao nível da PND, por um sistema de tomada de decisão fuzzy cujas variáveis de entrada são clínicas. Foi adquirido o sinal EMG de alta densidade (matriz de 64 eletrodos) dos músculos tibial anterior, gastrocnêmio medial, vasto lateral e bíceps femoral durante a contração isométrica a 10%, 20% e 30% da contração voluntária máxima. Simultaneamente, foi adquirido o sinal da força isométrica durante a flexão e extensão de joelho e tornozelo. Foram calculados o desvio padrão e a sample entropy da força, e o root mean square e a sample entropy do EMG. As diferenças entre os grupos para as variáveis obtidas da força e do EMG foram verificadas através de análises multivariadas (alfa=0,05). Resultados: No geral, durante a flexão de tornozelo, sujeitos moderados e graves apresentaram um maior desvio padrão da força, e sujeitos moderados apresentaram menor sample entropy da força. Durante a extensão de tornozelo, os sujeitos moderados apresentaram maior desvio padrão da força e todos os grupos diabéticos apresentaram menor sample entropy da força. Durante a extensão do joelho, os sujeitos moderados apresentaram um maior desvio padrão e uma menor sample entropy da força. O tibial anterior apresentou um maior root mean square no grupo ausente e uma menor sample entropy nos sujeitos leves. O gastrocnêmio medial apresentou maior sample entropy nos sujeitos moderados e graves. Os sujeitos graves apresentaram menor sample entropy no vasto lateral em todos os níveis de força estudados. Conclusões: A PND afeta a complexidade do sistema neuromuscular durante contrações isométricas de baixa intensidade, reduzindo a capacidade do sistema de se adaptar às demandas mecânicas desafiadoras. Os padrões de complexidade neuromuscular observados não estavam associados à gravidade da doença, com a maioria das alterações sendo observadas no grupo moderado / Introduction: The general proposal of this study is to get a better understanding on how motor control is affected in diabetic polyneuropathy (DPN) individuals. Fluctuations of the force and sEMG signal during isometric voluntary contractions have been studied as a simplified model of the physiological mechanism that underlies the control of movement. The analysis of the muscular recruitment patterns from lower limbs, obtained by high-density sEMG, together with the corresponding force signal outputs from knee and ankle joints, in the light of complexity analysis, adds to the knowledge of the disease effects in motor control. Additionally, examining the complexity of force and muscle activity of DPN individuals, along with the development of DPN from subclinical to the more severe stages, will help us understanding how the alterations will develop with the DPN progression. The hypotheses of this study are that: DPN alters the motor complexity, expressed as an increased amount of variability and a decreased structure of variability in sEMG and force outputs, and these alterations are aggravated by the severity of the disease. Methods: We assessed 10 control subjects and 38 diabetic subjects, classified as absent, mild, moderate, or severe DPN, by a fuzzy-system based on clinical variables. Multichannel sEMG (64-electrode matrix) of tibialis anterior, gastrocnemius medialis, vastus lateralis and biceps femoris muscles were acquired during isometric contractions at 10%, 20%, and 30% of the maximum voluntary contraction, and force levels were recorded during dorsiflexion, plantarflexion, knee extension and knee flexion. Standard deviation and sample entropy of force signals were calculated and root mean square and sample entropy were calculated from sEMG signals. Differences among groups of force and sEMG variables were verified using a multivariate analysis of variance (alpha=0.05). Results: Overall, during dorsiflexion contractions, moderate and severe subjects had higher force standard deviation and moderate subjects had lower force sample entropy. During plantarflexion, moderate subjects had higher force standard deviation and all diabetic subjects had lower entropy. During knee extension moderate DPN subjects demonstrated high force standard deviation and low force sample entropy. Tibialis anterior presented higher root mean square in absent group and lower entropy in mild subjects. For gastrocnemius medialis, entropy was higher in severe and lower in moderate subjects. Severely affected participants showed low sample entropy in vastus lateralis at all force levels. Conclusions: DPN affects the complexity of the neuromuscular system during low-level isometric contractions, reducing the system\'s capacity to adapt to challenging mechanical demands. The observed patterns of neuromuscular complexity were not associated with disease severity, with the majority of alterations recorded in moderate subject

A demonstração da formação de classes de equivalência é dificultada pela ausência de reforçamento durante os testes de relações emergentes que documentam suas propriedades, em particular quando se trata de sujeitos não-humanos e humanos com desenvolvimento atípico. O presente trabalho propõe uma alternativa metodológica para testar a formação de classes de equivalência sob condições de reforçamento diferencial. O primeiro estudo testou simetria e transitividade em humanos adultos verbalmente competentes com o propósito de avaliar o procedimento em condições favoráveis à demonstração da formação de classes de equivalência. O segundo estudo aplicou o procedimento na avaliação de simetria em pombos. Em termos gerais, os sujeitos foram treinados em uma linha de base de relações condicionais antes de serem submetidos a testes reforçados de simetria ou transitividade. Durante o teste de simetria, dois conjuntos de relações condicionais foram adicionalmente reforçados: um constituído das contrapartes simétricas de relações da linha de base, o outro de relações inéditas não simétricas formadas pela recombinação de estímulos da linha de base. Desempenhos mais precisos nas relações simétricas em comparação às relações inéditas sugeririam um controle condicional por simetria. A mesma estratégia foi empregada para avaliar transitividade. Em relação aos resultados, os participantes humanos responderam com acurácia superior nas relações simétricas e transitivas do que nas relações inéditas no transcorrer de cada teste. Esses achados demonstram a efetividade do procedimento em avaliar a emergência de relações que definem equivalência de estímulos. Os pombos, por sua vez, desempenharam ao nível do acaso tanto nas relações simétricas quanto nas relações inéditas em um primeiro teste envolvendo a metade dos estímulos da linha de base. Entretanto, depois que essas relações foram treinadas até alta acurácia, todos os sujeitos responderam com precisão superior nas relações simétricas durante um segundo teste envolvendo os estímulos restantes da linha de base. Esses resultados contrastam a maioria dos resultados de estudos anteriores com sujeitos não-verbais e sugerem que formação de classes de equivalência pode ser verificada em tais populações sob condições adequadas de treino e teste. / The lack of reinforcement in tests of emergent relations interferes with the demonstration of equivalence-class formation in nonhuman animals and humans with developmental disabilities. The present work proposes an alternative methodology to test equivalence-class formation under differential reinforcement conditions. The first study assessed symmetry and transitivity in verbally-able human adults in order to evaluate the proposed procedure. In the second study, such a procedure was applied to assess symmetry in pigeons. After subjects have been trained on the baseline conditional relations they were given either a symmetry or a transitivity reinforced test. During the symmetry test, two sets of conditional relations were additionally reinforced: symmetrical versions of the baseline relations and novel relations, formed by recombining stimuli from the baseline. Evidence for symmetry would be indicated by higher accuracies on the symmetrical than on the novel relations. Similar strategy was used to test transitivity. The results showed that human participants performed with higher levels of accuracy on the symmetrical and transitive relations than on the novel relations throughout each test. These founds indicate the efficacy of the procedure to test emergent relations that define stimulus equivalence. Pigeons, in turn, performed at chance-level in both symmetrical and novel relations in the first test involving half of the baseline stimuli. Nevertheless, after such relations have been trained to a high accuracy, all the pigeons matched at higher levels of accuracy on the symmetrical relations in the second test involving the remaining baseline stimuli. This result contrasts with the lack of symmetry reported in most of previous studies with nonverbal subjects and indicates that symmetry can emerge in such a population under adequate conditions of training and testing.

A análise operante dos movimentos dos olhos tem-se mostrado uma medida auxiliar no estudo de controle de estímulos, posto que diferentes topografias de controle de estímulo (TCE) correlacionam-se a diferentes padrões de movimento dos olhos, segundo dados recentes da literatura. O presente estudo buscou analisar experimentalmente os efeitos de diferentes TCE (seleção/rejeição) sobre o padrão dos movimentos dos olhos de quatro participantes submetidos a treinos de discriminação condicional e testes de equivalência. Figuras sem sentido, letras do alfabeto ocidental, números e letras do alfabeto grego foram utilizadas como estímulos visuais. Inicialmente, durante a fase de Linha de Base (LB), todos os participantes foram submetidos a um treino AB/BC e aos testes de transitividade (AC), simetria (CB e BA), equivalência (CA) e reflexividade (AA, BB e CC), nessa ordem. Em seguida, em seqüências distintas para cada participante, foram conduzidas diferentes fases de treino em que o controle por rejeição ou por seleção passaram a ser favorecidos por meio da manipulação das proporções de S+ e de S-. Na fase de Controle por Rejeição (RJ), os participantes foram submetidos a um treino DE/EF no qual o estabelecimento da TCE por rejeição fora favorecido; em seguida, foram realizados os testes (DF, FE, ED, FD, DD, EE e FF). Na fase de Controle por Seleção (SL), os participantes foram submetidos a um treino GH/HI no qual a TCE por seleção fora favorecida; em seguida, foram realizados os testes (GH, IH, GH, IG, GG, HH e II). Dois dos participantes foram submetidos às fases experimentais na ordem LB RJ SL; para os outros dois, a ordem das duas últimas fases foi invertida (LB SL RJ). Todos os participantes apresentaram alta porcentagem de acerto nos testes seguintes às fases LB e SL. Na fase RJ, somente um participante apresentou desempenho indicativo de controle por rejeição, ou seja, falhas sistemáticas nos testes de transitividade, equivalência e reflexividade. Para esse participante, na fase RJ, a topografia de olhar somente o S- antes de escolher um dos comparações foi ocorreu em alta freqüência comparada a olhar somente o S+. Nessa mesma fase, a freqüência e a duração do olhar para o S- também foram maiores quando comparadas ao S+. O inverso se deu na fase SL, ou seja, houve uma alta freqüência da topografia de olhar somente o S+, bem como houve maiores freqüências e durações de olhar ao S+ comparadas ao S-. De modo geral, para os demais participantes, os quais foram bem-sucedidos nos testes seguintes à fase RJ, a topografia de olhar antes de escolher um dos comparações, bem como a freqüência e a duração da fixação do olhar foram maiores para o S+ do que ao S- ao longo de todas as fases. O presente estudo mostra que diferenças nas TCE estabelecidas foram acompanhadas de diferenças na topografia, na freqüência e na duração do olhar para o S+ e o S-. Além disso, os resultados sugerem que é necessário investigar procedimentos capazes de garantir o estabelecimento do controle exclusivo por seleção ou rejeição. / The operant analysis of eye movements has been taken as an auxiliary measure in the study of stimulus control. Other researches have already shown that different stimulus control topographies (SCT) are correlated with different patterns of eye movements. The present study used an equipment to track the eye movements of four participants during conditional discrimination training and equivalence tests. It aimed to verify, for different sets of stimuli, the effect of different SCT (selection/rejection) over the eye movements patterns. Nonsense figures, letters, numbers and greek letters were used as visual stimuli. Initially, during the Base Line (BL) phase, all participants were submitted to AB/BC relations training and to the tests of transitivity (AC), symmetry (BA and CB), equivalence (CA) and reflexivity (AA, BB and CC), in this sequence, without biasing the establishment of any SCT. In the Rejection Control (RJ) phase, participants were submitted to DE/EF relations training in which the SCT reject was biased. After that, they went through the tests (DF, FE, ED, FD, DD, EE e FF). In the Selection Control (SL) phase, participants were submitted to GH/HI relations training in which the SCT select was biased. After that, they were submitted to the testes (GH, IH, GH, IG, GG, HH e II). Two participants were exposed to experimental phases in the sequence BL RJ SL. For the other ones the order of the last two phases were inverted (BL SL RJ). Following the suggestions of previews studies, in order to bias reject and select control, depending on the experimental phase, the proportions of S+ and S- during the training were manipulated. All participants showed high scores during the tests of BL and SL phases. In RJ phase, only one participant showed systematic failures in transitivity, equivalence and reflexivity tests a typical rejection performance. For this participant, in RJ phase, it was verified a high frequency of the topography of looking only at the S- before choosing one of the comparisons. In this phase, the frequency and the duration of looking at the S- were also higher then looking at the S+. The opposite was observed in the SL phase - a high frequency of the topography of looking only at the S+ before choosing and also a high frequency and duration of looking at the S+. In general, for those participants who did not failed in the testes of RJ phase, the topography, the frequency and the duration of looking at the S+ were higher when compared to the S- along all the experimental phases. The present study shows that for different SCT it was also observed differences in the topography, frequency and duration of looking at the S+ or S-. The results also suggest that it is necessary to investigate what kind of procedures are able to increase the chances of select and reject control to be exclusively establish during the training.