Journal of the experimental analysis of behavior
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Goldfish were trained to swim back and forth in a shuttle tank to avoid unsignalled shocks. The response-shock interval and the shock-shock interval were always of equal duration; both were either 15, 30, 45, or 60 sec. Response rates varied inversely with response-shock-shock-shock interval duration, as has been found with rats. ⋯ As the response-shock-shock-shock interval increased, the fish made increasingly more responses than necessary to avoid all shocks. Interresponse-time distributions showed that response probability rose to a maximum at about 15 to 25 sec after a response, regardless of the response-shock-shock-shock interval. Thus, at the longer intervals the fish were responding too early in the response-shock-shock-shock interval to minimize response rates.
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Hyperthermia was observed at the end of each conditioning session in rats trained to avoid electric shocks by jumping on a platform. The temperature rise was also observed after the conditioned behavioral response was well established and was elicited even in the absence of shocks. There was no tendency for the hyperthermia to diminish over the course of nine extinction sessions.