Made available in DSpace on 2016-04-29T13:18:10Z (GMT). No. of bitstreams: 1 Mariana Queiroz Martins Pedroso.pdf: 1093596 bytes, checksum: 07eb393466b02df8274ee63254b1d002 (MD5) Previous issue date: 2005-05-16 / Replicating Iversen s (1993) procedure, this study s goal was to increase the comprehension of the running response of rats on an activity wheel when running was a consequence of responding on a fixed-ratio schedule. The study also explored the impact of a restricted period of food availability on the reinforcing value of wheel running. Body weight, food and water consumption of six female rats were systematically measured. Five subjects were also submitted to a procedure designed to install wheel-running as a consequence for lever pressing. After baseline measures of wheel running, a gradual restriction of the session time when wheel-running was possible was implemented, followed by the shaping of a lever pressing response reinforced by wheel-running, and a phase when lever pressing was maintained by intermittent reinforcement on a FR. The FR values initially were increased automatically and later the FR values were increased based on the analysis of the subject s responses. One subject was finally submitted to an extinction procedure of the lever pressing response. The availability of food also varied during experimental phases concomitantly with the manipulation of lever pressing and wheel running: food was initially available all the time, later food was available for 90 minutes daily, and, finally, it was available all the time again for some subjects.. Results indicated that the lever pressing that produced wheel running as a consequence was acquired and maintained for 4 of 5 subjects. Nevertheless these responses were emitted at low rates, and were acquired only after a long training. For one subject, the lever pressing response was acquired only when food was its consequence and was, then maintained when the consequence became wheel-running. Results also showed that rate of lever pressing and the number of wheel turns decreased as the value of fixed ratio increased, and that weight loss did not depend on the number of wheel turns, but seemed to depend on the time restriction of food availability. It is discussed that for 3 subjects the time restriction of food availability was an establishing operation for wheel-running / Similar ao procedimento de Iversen (1993), este estudo buscou compreender o funcionamento da resposta de andar na roda como reforço, em esquema de reforçamento em FR e explorou o impacto da restrição do tempo de alimento disponível sobre o valor reforçador de andar na roda. Seis ratas foram submetidas à linha de base de peso corporal, consumo de alimento e água. Destas, cinco foram designadas às seguintes fases tendo a possibilidade de andar na roda: sessões de linha de base, redução gradual do tempo de possibilidade de andar na roda; modelagem da resposta de pressão à barra; reforçamento intermitente em FR com aumento automático do valor da FR, aumento do valor da FR determinado pela análise das respostas emitidas pelos sujeitos e extinção da resposta de pressão à barra. Sobre o alimento, destacam-se as seguintes condições: alimento disponível por tempo integral, 90 de alimento disponível por dia e alimento por tempo integral. Tais condições acompanharam as manipulações das variáveis relativas a andar na roda. Os resultados apontaram que quatro de cinco sujeitos adquiriram com muito treino e mantiveram com taxas baixas a resposta de pressão à barra tendo a possibilidade de andar na roda como conseqüência, diferente do obtido por Iversen (1993). Para um sujeito, inclusive a resposta de pressão à barra só foi instalada usando alimento como reforço, e depois mantida com a resposta de andar na roda. Observou-se também que as taxas de respostas de pressão à barra e o número de voltas na roda diminuíram com o aumento do valor da FR, e que a perda de peso dos sujeitos não dependeu da quantidade de voltas na roda e sim da restrição do tempo de alimento disponível. Pode-se dizer que a restrição do tempo de alimento foi uma operação estabelecedora que alterou a efetividade reforçadora do andar na roda para quatro dos sujeitos