Delay periods, warm-up treatments and vicious-circle behavior in rats
Jackson, John L. (Student of psychology)
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Vicious-circle (or self-punitive) behavior is typically- defined as the greater persistence of a response that results in punishment, relative to the persistence of the same response when not punished. Previous vicious-circle studies have found that a delay period (an unusually long intertrial interval) inserted at some point during extinction trials results in reductions in performance. Other studies have found that a warm-up treatment (typically shock or CS-US presentations) can be effective in reversing the effects of a delay period. The present study examined the effects of a delay period and a delay period followed by a warm-up treatment upon vicious-circle behavior. Ninety male albino rats were given 15 training trials to escape a 1.O-ma footshock in a straight alleyway. Following training trials, 45 of the rats were exposed to a regular extinction (RE) condition, while the other 45 rats were given punished extinction (PE). RE subjects experienced no further shock in the alleyway during extinction trials, whereas the midsegment of the alleyway remained electrified for PE subjects. A 20-min shock-free delay period was given to 15 RE and 15 PE subjects between extinction Trials 20 and 21. Similarly, 15 RE and 15 PE subjects received a 20-min delay period between extinction Trials 20 and 21, but also received a warm-up treatment which consisted of a 5-sec footshock after 19 min of delay. Massed extinction trials were resumed immediately after the delay treatments. The remaining 15 RE and 15 PE subjects served as control subjects, receiving massed extinction trials. The intertrial interval, with the exception of the delay period, was 60 sec for all subjects. Thus, six groups of 15 subjects each were formed by the 2x3 factorial combination of extinction condition and delay treatment. The rats were run until they met an extinction criterion or a maximum of 100 extinction trials. The subjects* performance was evaluated in terms of start speed, prepunishment speed, alleyway speed, and trials to extinction. The results of the study indicated that a vicious- circle effect was obtained before the delay treatments were administered. In terms of resistance to extinction, a vicious-circle effect was obtained at all levels of delay treatment. The delay treatments had no significant effect on the resistance to extinction of RE subjects, while the shock-free delay period significantly reduced the resistance to extinction of PE subjects. PE subjects that received a warm-up treatment were not different in resistance to extinction from no-delay control subjects. In terms of alleyway speed, the shock-free delay period reduced the performance of RE and PE subjects, whereas the response facilitation produced by the warm-up treatment was maintained only for PE subjects. Of all 45 PE subjects, only six rats, all of whom received the shock-free delay period, extinguished immediately after the delay period. These rats received two or fewer shocks in the alleyway before they stopped running. All PE subjects that received a delay treatment displayed a decrement in alleyway speed immediately following the delay treatment. Those PE that did not extinguish immediately after the delay treatment were not different in performance during later extinction trials from no-delay control PE subjects. These results were discussed in terms of conditioned fear, postshock emotionality, and decrements in memory retrieval. It was felt that the PE subjects in the present study would extinguish only if several conditions were met: 1) The conditioned fear response to the start area had been partially extinguished during predelay extinction trials, 2) the delay period eliminated postshock emotionality and the internal cues for the running response which result from shock, and 3) the animal did not experience more than two shocks in the alleyway following the delay period.