The purpose of this research was to explore the effects of small monetary or economic gains and/or losses on choice behavior through the use of a computerized game and to determine gain/loss ratio differences using both behavioral and electrophysiological measures. Participants (N=53) played the game in several 36 minute sessions. These sessions operated with concurrent variable-interval schedules for both rewards and penalties. Previously, asymmetrical effects of gains and losses have been identified through cognitive studies, primarily due to the work of nobel laureates Daniel Kahneman and Amos Tversky (1979). They found that the effect of a loss is twice (i.e., 2:1) that of a gain. Similar results have been observed in the behavioral laboratory as exemplified by the research of Rasmussen and Newland (2008), who found a 3:1 ratio for the effect of losses versus gains. The asymmetry of gains and losses was estimated behaviorally and through event-related brain potentials (ERPs) and the cognitive (Kahneman and Tversky) and behavioral (Rasmussen and Newland) discrepancy elucidated. In the game, the player moves an animated submarine around sea rocks to collect yellow coins and other treasures on the sea floor. Upon collecting a coin, one of three things can happen: The player triggers a penalty (loss), the player triggers a payoff (gain), or there is no change. The behavioral measures consisted in counting the number of clicks, reinforces, and punishers and then determining ratio differences between punished (loss) and no punished condition (gain) conditions. The obtained gain/loss ratio corresponded to an asymmetry of 2:1. Similarly ratio differences were found between male and female, virtual money and cash, risk averse versus risk seeking, and generosity versus profit behavior. Also, no ratio difference was found when players receive information about other player's performances in the game (players with information versus players without information). In electroencephalographic (EEG) studies, visual evoked potentials (VEPs) and ERPs components (e.g., P300) were examined. I found increased ERP amplitudes for the losses in relation to the gains that corresponded to the calculated behavioral asymmetry of 2:1. A correlational strategy was adopted that sought to identify neural correlates of choice consistent with cognitive and behavioral approaches. In addition, electro cortical ratio differences were observed between different sets of electrodes that corresponded to the front, middle, and back sections of the brain; differences between sessions, risk averse and risk seeking behavior and sessions with concurrent visual and auditory stimuli and only visual were also estimated.

Made available in DSpace on 2016-06-02T19:46:04Z (GMT). No. of bitstreams: 1 2367.pdf: 1678982 bytes, checksum: 2e92e0dbbed089297a09a8f7ee3e45de (MD5) Previous issue date: 2009-02-27 / Financiadora de Estudos e Projetos / One of the most complex human abilities is the symbolic thought that is related to the acquisition of arbitrary relational repertoires such as conditional discrimination. However, research on the acquisition of these repertoires in babies up to 24 months was hampered by methodological difficulties. The literature has identified some critical variables for the maintenance of these participants in experimental situation and other variables related to the process of learning the tasks by the babies. This research investigated procedures for teaching simple and conditional visual discrimination in infants aged 15 to 21 months. In the first part of the investigation - Study 1 - the tasks proposed to the participants were simple simultaneous discrimination and delayed identity conditional discrimination. Various industrialized toys had different functions as stimulus and were exposed in a motorized apparatus specially built for the study. The first study evaluated the effects of variation of the order and amount of exposure of participants to differential reinforcement contingencies on the performance of babies in simple discrimination tasks. In Study 2, simple simultaneous discrimination tasks, discrimination reversal and delayed arbitrary conditional discrimination tasks have been proposed to the participants in a play context where some photographs of animals were exposed in a bound book of paper card. This study evaluated the effects of the requirement of observational and choice responses similar to those issued in natural situation of free play between adults and babies. The investigation has identified effective conditions of teaching in two aspects - achievement of the learning criteria of discrimination tasks by participants and for their permanence in the experimental situation over the experimental procedures, respectively: 1) the procedure of contact with differential reinforcement contingencies that occurred in more trials and planned the positive reinforcement (S+) to occur in the first trial; 2) the procedure of requirement of observational and choice responses present in the baby repertoire and the experimental arrange of the effective reinforcer stimuli as part of the task (exerting function of reinforcer or sample stimulus). The general discussion stressed the importance of knowledge by researchers from the expected repertoire of participants in a specific age for planning tasks and requiring responses closer form that naturally emitted in babies daily activities. Likewise, researchers must know the individual repertoire of each baby so they can arrange the effective reinforcer stimulus for each participant. / Uma das habilidades humanas mais complexas, o pensamento simbólico, está relacionado à aquisição de repertórios relacionais arbitrários, como as discriminações condicionais. Entretanto, a investigação sobre a aquisição destes repertórios em bebês menores de 24 meses esbarra em dificuldades metodológicas. A literatura tem identificado algumas variáveis favoráveis à manutenção dos pequenos na situação experimental e outras variáveis relacionadas à aprendizagem da tarefa pelos bebês. Este trabalho investigou em dois estudos procedimentos de ensino de discriminações visuais simples e condicionais com bebês de 15 a 21 meses. As tarefas propostas aos participantes no Estudo 1 foram discriminações simples simultâneas e discriminações condicionais por identidade com atraso: diversos brinquedos industrializados que exerciam diferentes funções de estímulo eram expostos em um aparato motorizado especialmente construído para o estudo. Foram verificados os efeitos da variação da ordem e quantidade de exposição dos participantes às contingências de reforçamento diferencial no desempenho dos bebês nas tarefas de discriminações simples e discriminações condicionais por identidade. No Estudo 2 as tarefas de discriminação simples simultânea, reversão das discriminações e discriminação condicional arbitrária simultânea foram propostas ao participante pela exposição de fotografias de bichos em um livro de papel cartão encadernado. Foi verificado o efeito do requerimento de respostas de observação e escolha similares àquelas emitidas em situação natural de brincadeira livre entre adultos e bebês. Como condições eficientes de ensino, para o alcance dos critérios de aprendizagem de discriminação pelos participantes e para sua permanência na situação experimental ao longo dos procedimentos planejados, pode-se destacar respectivamente: 1) o procedimento em que o reforçamento diferencial previa reforçamento positivo (S+) na primeira tentativa e ocorria em maior quantidade de tentativas; 2) o procedimento com requerimento de respostas de escolha e observação presentes no repertório do bebê e a programação de estímulos reforçadores efetivos como parte da tarefa (como estímulos reforçadores ou estímulos modelo). A discussão geral ressaltou a importância do conhecimento pelos pesquisadores dos repertórios esperados da faixa etária dos participantes, para o planejamento de tarefas e respostas mais próximas daquelas naturalmente emitidas no cotidiano dos pequenos, assim como do repertório individual de cada bebê para o arranjo de estímulos reforçadores efetivos para cada participante.