Effect of mithramycin on calcium and hydroxyproline metabolism in patients with malignant disease

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Rapid extinction of an avoidance response following a period of response prevention in the avoidance apparatus

Thirty-three rats were trained to avoid shock in a novel avoidance apparatus that required S to climb or jump onto a ledge in order to avoid. When Ss had achieved a learning criterion, they were assigned to one of three groups, each of which received a different experimental treatment prior to extinction training. Group I, the normal-control group, received no interruption between acquisition and extinction. Group II, the time-control group, spent a 5-min. interval on the safety ledge between the last acquisition trial and the first extinction trial. Group III, the experimental response-prevention group, spent a 5-min. interval on the grid floor of the apparatus between acquisition and extinction. For Group III Ss, the ledge was removed from the apparatus to prevent the occurrence of avoidance responses during the response-prevention interval. The results showed that Group III (response-prevention) Ss extinguished significantly sooner, confirming previous findings.