La présente recherche étudie l'apprentissage et la généralisation dans une tâche de catégorisation de stimuli visuels multidimensionnels. Il s'agit de vérifier si les patrons de classification identifiés pour chaque participant et la reconnaissance des stimuli peuvent être expliqués par l'emploi de règles et la mémorisation d'exceptions. Une méthode formelle de minimisation booléenne a permis d'effectuer la synthèse des différents types de représentation des catégories selon le nombre de classifications correctes observé. Trois types de représentation obtenus correspondent à l'utilisation d'une règle unidimensionnelle, accompagnée d'aucune, d'une ou de deux exceptions apprises. L'analyse de la reconnaissance des stimuli, de l'apprentissage des exceptions et de la généralisation à de nouveau stimuli, suggèrent que l'apprentissage d'une exception peut reposer sur la formulation d'une nouvelle règle sans faire appel à un processus de mémorisation permettant l'identification d'un stimulus en particulier.

Polymeric materials with inherent stimulus response represent an ever-growing area of research. In particular, block copolymers demonstrate exciting properties owing to their enhanced mechanical strength and microphase separation. Incorporating functionality into block copolymers proves useful in enhancing their utility. Presently, synthesis and subsequent post-polymerization modification achieved this for a range of block copolymers. In particular, neutralization of acid-containing polymers readily imparted ionic functionality and yielded microphase-separated block copolymer domains, enhancing polymer thermomechanical properties and ion transport. An ABA triblock copolymer composed of mechanically reinforcing polystyrene outer blocks and ionic central poly(1-methylimidazolium acrylate) block acted as a host for ionic liquid that caused an evolution in bulk morphology, resulting in enhanced ionic conductivity. The resulting membrane also exhibited a strong electromechanical actuation response under applied potential. Adding ionic liquid doped with a corresponding lithium salt enabled evaluation of sulfonated block copolymers as components of ternary polymer electrolytes, relevant for battery applications. Modification of a sulfonic acid-containing pentablock copolymer presented photocurable functional groups to the ionic domains which enabled their UV irradiation-induced curing. This novel route of modifying ion-containing block copolymers resulted in enhanced thermomechanical properties and enabled healing of physical defects in the film, unprecedented for ion-containing block copolymers. Covalent networks represent a relevant area of research for a wide variety of applications such as coatings, adhesives, and scaffolds. Careful design of degradable crosslinkers enables stimulus response in these networks by eliminating covalent crosslinks and affording a soluble product. Extension of poly(ethylene glycol) methacrylate-based network formation into three dimensions using microstereolithography resulted in novel acid-degradable 3D-printed parts. An additional study investigated mixtures of acrylamide-modified poly(vinyl alcohol) and poly(ethylene glycol) diacrylate as water-soluble resins for the direct formation of hydrogels from solution. Photorheology and photocalorimetry investigated the thermal and mechanical changes inherent in the curing process and evaluated the mixtures as a platform for microstereolithography. / Ph. D.

In his book Ritual House, Ralph Knowles states, "The houses we inhabit, the cities surrounding our houses, even the clothes we wear - all are shelters we erect against the elements. But they are also manifestations of ancient rituals, developed in response to nature's rhythms" (2006). Implicit within this quote is the importance of nature's rhythms in our lives, particularly those related to the movement of the sun. Many built environments have no connection to the exterior. Those who work in these spaces are disconnected from these natural rhythms and often experience detrimental physiological effects. However, technology has the potential to reintroduce aspects of natural rhythms into built environments. This research crossed disciplinary boundaries separating architecture, engineering, psychology, and building science during the design of an architectural intervention for an interior workspace known as the Sandbox, at Virginia Tech. The design proposal includes skylights that combine Photovoltaic-integrated glazing with LED lighting to create conditions that stimulate the occupants while connecting inside to out. To reestablish a connection to natural rhythms the BIPV energy monitoring is used during the day to record variations in solar radiation which at night are played back through intensity and color variations of LED lighting. The effect of the LED lighting was compared with the sunlight entering through the skylights using quantitative analysis methods and qualitative visual comparison tools including time lapse photos and videos. The research merges architectural design, lighting technology and BIPV to demonstrate a proof-of-concept for the reintroduction of natural rhythms into built environments. / Master of Science

When something is not attended to by a person, even when it is right before them, they won't perceive it. This is known as inattentional blindness (Mack & Rock, 1998). Sometimes information missed due to inattentional blindness is trivial but inattentional blindness can become a problem when it hinders people from responding to something appropriately when a response is needed. When a visual cue is missed there can be an impact on decision-making. Variations in color luminance may also be a factor in one's ability to attend to something. For example, if a person is attending to a number of objects that are one color shade (for instance, dark green), it may be possible that this person might not see an additional object appear in their field of view (FOV) if it is the same color and shade. Conversely, the opposite might be true that a person is more likely to attend to the additional object if it is the same dark green color, opposed to an object that is colored a lighter green. This research investigated whether some variations of luminance of the same color (for example, dark green to light green) can affect one's ability to attend an additional object entering one's FOV. A scenario was presented to tank gunners that required them to observe objects of one color (dark green) while an additional object was briefly presented to them colored either dark green or light green. In this between-subjects study, 48 participants observed four dark green and four light green enemy tanks moving about the battlefield. Each was given a task that involved monitoring the dark green tanks only. During their monitoring, an additional vehicle (M981A3 FIST-V) briefly entered and exited their FOV. The additional vehicle was presented to 24 participants colored dark green. For the other 24, it was presented colored light green. This research addressed whether there was an association between color luminance, FOV, or focused attention and detection of the FIST-V. The results did not indicate an association between FOV and detection of the FIST-V [÷2(1, N = 48) = 0.08, p = 1.0]. Nor was there an association between focused attention and detection of the FIST-V using the following self-reporting questionnaires for determining levels of focused attention: ETAS [÷2(1, N = 48) = 2.06, p = 0.20], the CFQ [÷2(1, N = 48) = 0.75, p = 0.56], and the DAPI [÷2(1, N = 47) = 1.39, p = 0.75]. In the same manner, there was also no association between field dependence and detection of the FIST-V [÷2(1, N = 43) = 0.34, p = 0.75]. There was, however, an association between color luminance and detection of the FIST-V [÷2(1, N = 48) = 36.80, p < 1.0e-8]. / Master of Science

No / Dynamic correction of monochromatic aberrations of the eye is known to affect the accommodation response to a step change in stimulus vergence. We used an adaptive optics system to determine how the temporal location of the correction affects the response. The system consists of a Shack-Hartmann sensor sampling at 20 Hz and a 37-actuator piezoelectric deformable mirror. An extra sensing channel allows for an independent measure of the accommodation level of the eye. The accommodation response of four subjects was measured during a +/- 0.5 D step change in stimulus vergence whilst aberrations were corrected at various time locations. We found that continued correction of aberrations after the step change decreased the gain for disaccommodation, but increased the gain for accommodation. These results could be explained based on the initial lag of accommodation to the stimulus and changes in the level of aberrations before and after the stimulus step change. Future considerations for investigations of the effect of monochromatic aberrations on the dynamic accommodation response are discussed.

The purpose of this experiment was to compare the effects of combining negative reinforcement and positive reinforcement during teaching with the effects of using positive reinforcement alone. A behavior was trained under two stimulus conditions and procedures. One method involved presenting the cue ven and reinforcing successive approximations to the target behavior. The other method involved presenting the cue punir, physically prompting the target behavior by pulling the leash, and delivering a reinforcer. Three other behaviors were trained using the two cues contingent on their occurrence. The results suggest that stimuli associated with both a positive reinforcer and an aversive stimulus produce a different dynamic than a situation that uses positive reinforcement or punishment alone.

This research is about evaluating vision in the periphery. Peripheral vision is of fundamental importance in the performance of our everyday activities. The aim of this thesis is to develop methods suitable for the evaluation of peripheral vision and to assess how different visual functions vary across the visual field. The results have application both within the field of visual rehabilitation of people with central visual field loss (CFL)and as well as in myopia research. All methods for assessing peripheral vision were implemented with adaptive psychophysical algorithms based on Bayesian statistics. A routine for time-efficient evaluation of peripheral contrast sensitivity was implemented and verified for measurements out to 30° in the visual field. Peripheral vision was evaluated for different properties of the stimuli: sharpness, motion, orientation, and extent. Optical quality was controlled using adaptive optics and/or corrective spectacles specially adapted for the peripheral viewing angle. We found that many peripheral visual functions improved with optical correction, especially in people with CFL. We also found improvements in peripheral contrast sensitivity for low spatial frequencies when stimuli drifted at 5 to 10 Hz; this applies both for people with normal vision and those with CFL. In the periphery, it is easier to see lines that are oriented parallel with respect to the visual field meridian. We have shown that this directional bias is present for both resolution and detection tasks in the periphery, even when the asymmetric optical errors are minimized. For accurate evaluation of peripheral vision, we therefore recommend using gratings that are oriented oblique to the visual  field meridian. The directional bias may have implications in how peripheral image quality affects myopia progression. Another proof that peripheral vision can influence central visual function is the fact that, when the stimulus extent was increased beyond the fovea, the blur in the stimulus was less noticeable. / Denna forskning handlar om att utvärdera synen i periferin. Vår perifera syn är ovärderlig i det dagliga livet. Målsättningen med denna avhandling är dels att utveckla metoder speciellt lämpade för perifer synutvärdering och dels att mäta hur olika synfunktioner varierar över synfältet. Resultaten har tillämpning både inom synrehabilitering för personer med centraltsynfältsbortfall och inom närsynthetsforskning. Adaptiv psykofysisk metodologi baserad på Bayesiansk statistik användes vid all utvärdering av det perifera seendet. Vi implementerade en rutin för tidseffektiv mätning av perifer kontrastkänslighet och verifierade den ut till 30° i synfältet. Den perifera synen utvärderades för olika egenskaper hos objektet: skärpa, rörelse, riktning och utbredning. Skärpan kontrollerades med hjälp av adaptiv optik och/eller glasögonkorrektion speciellt anpassad för den perifera synvinkeln. Vi fann att många periferasynfunktioner förbättras av optisk korrektion, särskilt för personer med centralt synfältsbortfall. Vi hittade även förbättringar i periferkontrastkänslighet för låga ortsfrekvenser när objektet modulerades med hastigheter mellan 5 och 10 Hz, vilket gäller både normalseende och personer med centralt synfältsbortfall. I periferin är det lättare att se linjer som är orienterade parallellt med synfältsmeridianen. Vi har visat att denna riktningsbias gäller både för upplösning och detektion i periferin, även när de asymmetriska optiska felen minimeras. För bästa mätnoggrannhet rekommenderar vi därför att använda randmönster som ligger snett relativt synfältsmeridianen. Denna riktningsbias skulle även kunna påverka hur den perifera bildkvalitén inverkar på utvecklingen av närsynthet. Ytterligare ett bevis för att perifer syn kan påverka den centrala synfunktionen är att, när objektets utbredning ökades, uppfattade personen det som mindre suddigt. / <p>QC 20160826</p>

L’addiction aux drogues peut être considérée comme une maladie neurologique chronique avec des rechutes récurrentes en période d’abstinence qui constituent le problème majeur dans le traitement de l’addiction aux drogues. Grâce à un modèle animal de rechute, il a été montré qu’un rongeur pouvait réinstaller un comportement de recherche de drogue lorsqu’il était réexposé à la drogue elle-même, à des indices associés à la drogue, ou encore à un stress. Dans notre équipe, nous avons évalué la contribution relative des différentes propriétés de la cocaïne, de l’héroïne et de la nicotine (incitative, discriminative et renforçante) dans la réinstallation d’un comportement de recherche de nourriture. Afin de dissocier les propriétés discriminatives et renforçantes, les rats ont été entraînés à s’auto-administrer une récompense alimentaire. Nous avons alors trouvé que : 1) La cocaïne et la nicotine agissent comme des stimuli internes qui acquièrent un contrôle discriminatif sur le comportement, étant donné que la cocaïne et la nicotine, contrairement à l’héroïne, peuvent réinstaller un comportement éteint de recherche de nourriture lorsque ce comportement a été préalablement acquis sous les effets de la cocaïne et de la nicotine, respectivement. 2) La réinstallation induite par la cocaïne et la nicotine est indépendante de la valeur actuelle de la récompense, ce qui indique que la cocaïne et la nicotine contrôlent l’activation de comportements automatiques, habituels, liés à la drogue. Puis, afin d’identifier la façon dont les drogues d’abus entraînent la formation d’habitudes, nous avons également étudié les effets d’une sensibilisation à la cocaïne à différents moments d’un apprentissage instrumental pour une récompense alimentaire, après une dévaluation de la récompense. Nous avons alors trouvé que la sensibilisation à la cocaïne ne favorisait pas le développement de comportements de type habituel. Cette série d’expériences constitue une première étape dans la comparaison des processus automatiques produits par la cocaïne et la nicotine. Si l’activation de comportements de type habituel, automatique, peut être généralisée à d’autres drogues d’abus, nous pourrons considérer que la rechute vers la recherche et la prise de drogue est en partie sous le contrôle de processus automatiques, ce qui pourrait expliquer la forte probabilité de rechute, même après de longues périodes d’abstinence et malgré la connaissance des conséquences néfastes qui en découlent. / Drug addiction can be considered as a chronic brain disease with recurrent relapse during abstinence periods which remains the major problem for the treatment of drug addiction. Using an animal model of drug relapse, it has been shown that a rodent can reinstate a drug-seeking behavior when re-exposed to the drug itself, drug associated cues or stress. In our research group, we assessed the relative contribution of the different properties of cocaine, heroin and nicotine (incentive, discriminative and reinforcing) in food-seeking reinstatement, and in order to dissociate the discriminative from the reinforcing properties, rats were trained to self-administer a non-drug reward (food). We found that: 1) Cocaine and nicotine act as internal stimuli that acquires discriminative control over behavior, since cocaine and nicotine, but not heroin, can reinstate an extinguished food-seeking behavior when this behavior has been previously performed under the effects of cocaine and nicotine respectively. 2) Cocaine- and nicotine-induced reinstatement is independent of the current value of the outcome, which indicates that cocaine and nicotine control the activation of automatic, drug-related habitual behaviors. Then, in order to identify the way drugs of abuse lead to the formation of habits, we also examined the effects of cocaine sensitization at different stages of instrumental training for a food reward after outcome devaluation. We found that, globally, cocaine sensitization does not promote the development of habit-based behaviors. This series of experiments represent a first step in the comparison of automatic processes produced by cocaine and nicotine. If the activation of automatic, habit-based behaviors can be generalized to other drugs of abuse, we could consider that relapse to drug-seeking and drug-taking is partly under the control of automatic processes, which could explain the high probability of relapse, even after extended periods of abstinence and despite the knowledge of the adverse consequences.

A agenda de pesquisa da discriminacao condicional e composta por diversos procedimentos que investigaram a formacao de classes de equivalencia. Dentre eles: o procedimento Go/Nogo com estimulos compostos; o procedimento Yes/No; o procedimento Respondent-type; o procedimento de pareamento de estimulos envolvendo uma resposta (Stimulus Pairing Response); e o procedimento de pareamento de estimulos envolvendo uma resposta de orientacao (Stimulus pairing Orientation Response). No Respondent-type a condicionalidade entre os estimulos nao foi demonstrada em treino, mas sim por meio do desempenho dos participantes em condicoes de testes das relacoes emergentes. A condicionalidade nao poderia ser demonstrada por respostas diferenciais aos pares de estimulos relacionados em condicoes de treino, uma vez que nenhuma relacao R-S r foi programada. Apesar de nenhuma resposta ser requerida nessas condicoes, existem respostas que naturalmente ocorrem frente ao ambiente programado (e.g respostas sensoriais) e que sao relevantes para o desempenho nas tarefas, no caso, os testes. Em contingencias de controle de estimulos, respostas sensoriais ou de orientacao sao necessarias, primeiramente, por colocarem os participantes em contato com as propriedades relevantes dos estimulos que compoe o ambiente programado. Alem da relevancia por colocar o organismo em contato com as propriedades relevantes dos estimulos, a agenda experimental demonstrou que as respostas de orientacao tambem influenciam na emergencia de relacoes transitivas. Tendo em vista a relevancia das respostas de orientacao, o presente estudo tem como objetivo rastrear medidas da resposta de orientacao por meio do rastreamento dos movimentos oculares de participantes expostos ao procedimento Respondent-type. Explorar medidas da resposta de orientacao em treino sem reforcamento diferencial e testes das relacoes emergentes pode ser uma maneira de contribuir com a investigacao das variaveis de controle dessas respostas e, com isso, permitir a manipulacao de propriedades espaco-temporais eficientes. Apesar das classes serem formadas a partir de treino Respondent-type (sem programacao de R S r), sua demonstracao, em condicao de teste, seria acompanhada pela demonstracao de observacao seletiva? De acordo com os resultados, nove de dez participantes demonstraram a emergencia de classes equivalentes. Assim, a replicacao foi bem-sucedida. Dados obtidos atraves do equipamento de rastreamento dos movimentos oculares permitiram a identificacao de observacao seletiva nos testes em MTS, mesmo nao havendo programacao de relacao R S r em treino. Por fim, a demonstracao de observacao seletiva permitiu a elaboracao de hipoteses baseadas em aspectos do procedimento que permitiram o estabelecimento de funcoes de estimulos corretos e incorretos na tarefa experimental (uma vez que o treino das relacoes condicionais nao era um treino discriminativo) / Conditional discrimination literature studies the formation of equivalent classes through several different procedures, such as: the Go/No-go procedure with compound stimuli; the Yes/No procedure; the Respondent-type procedure; the Stimulus Pairing Response procedure; and the Stimulus Pairing Orientation Response procedure. Regarding the Respondent-type procedure, the conditionality between stimuli was not demonstrated in training, but it was instead observed in the performance of participants in emergent relations test conditions. Conditionality could not be demonstrated by differential responding in training, since R-S relation was not programmed in this study. Even though no responses are required in these conditions, some responses that naturally occur in the programmed environment (i.e. sensorial responses) are relevant for the performance of tasks, which in this case are the tests. In stimuli control conditions, sensorial or orientation responses are needed, first, to put the participants in contact with the relevant properties of the stimulus that form the programmed environment; and second, to demonstrate that such responses also influence the creation of transitive relations. Considering how relevant orientation responses are, this study aims to track measurements for such responses through tracking the eye movements of participants exposed to Respondent-type procedure. Through the exploration of orientation responses in trainings that lack differential reinforcement, and of tests for emerging relationships, this study can contribute to research investigating the variables of orientation responses, and allow for a manipulation of their spatial-temporal properties. Although classes are formed through Respondent-type training (without an R-S response being programmed into it), would their establishment, in testing conditions, be accompanied by the establishment of selective observing? According to the results, nine in ten participants observed the establishment of equivalent classes, which indicate that our replication was successful. Data obtained through eye-movement tracking allowed us to identify selective observation in MTS training even through no R-S relationship was programmed. Lastly, the establishment of selective observation allowed us to formulate hypothesis based on certain aspects of the procedure, which allowed for the establishment of functions of correct and incorrect stimuli in the experimental task (because the training for conditional relationships was not a discriminative training)

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.