Self-punitive behavior : the effects of stimulus change on fear
Walker, Lila K.
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Self-punitive behavior refers to punishment-induced response facilitation. Following shock-escape training in a straight alley runway, animals given shock in an intermediate (second) segment of the runway (punished extinction) show more resistance to extinction of running than animals given no shock. Perconte, Benson and Butler, in 1981, reported that changing the alley cues immediately before punished extinction reduced self-punitive running when the changed stimuli were located two alley segments preceding shock but had no effect when the changed alley stimuli were in the segment immediately preceding the shock segment. The authors offered a conditioned fear interpretation of their findings which assumed that during punished extinction fear was rapidly reconditioned to the segment immediately preceding shock but not to earlier segments. The present study directly tested the effects of stimulus change on conditioned fear. Sixty male rats were exposed to 15 shock-escape training trials in a 3-segment straight alley runway. For half of the subjects, the alley cues were changed at the start of punished extinction. Half of the stimulus-change subjects encountered the change in the startbox; the other half in the first alley segment. Following 15 punished-extinction trials, animals were placed in either the startbox or the first alley segment and allowed to escape into a safebox by jumping over a hurdle located in the sidewall of the segment. Speed (1/lat) of hurdle jumping over 50 trials served as the dependent measure. Hurdle-jumping speeds of animals exposed to stimulus change in the first segment did not differ from those of animals exposed to unchanged stimuli in the first segment. In contrast, hurdle-jumping speeds of animals exposed to stimulus change in the startbox were significantly slower than those exposed to unchanged stimuli in the startbox. These results support the hypothesis that midsegment shock maintains conditioned fear of the first alley segment cues during punished extinction.