Psychology ETDs

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Sixty-six albino rats obtained from Simonson Laboratories were weaned at 21 days and randomly assigned, using a split litter technique, to groups of 1 (isolation) or 5 (control) where they were housed for 62 days. At the end of the rearing period, subjects were individually housed and given one five-minute habituation trial daily, for 6 days, to a standard plexiglass alleyway. On the seventh day, a standard, one-way instrumental avoidance paradigm using .6 ma shock was instituted. After achieving an acquisition criterion of 8/10 successive, successful shock avoidances, subjects were exposed to Brown's vicious circle paradigm using 0, .4, .6, or 1.0 ma shock. Extinction was carried out for 60 trials and acquisition and extinction trials were massed. It was observed that isolates and controls made similar numbers of errors prior to achieving the acquisition criterion and that both attained similar running speeds on the last 8 successful acquisition trials. During the vicious circle phase, control animals replicated the vicious circle effect. Controls exhibited increasing speed and more trials to extinction with greater shock intensities. Isolates failed to replicate the vicious circle phenomenon, although they responded at higher shock intensities (.4, .6, 1.0 ma) in a manner similar to controls. These findings were interpreted in the light of existing explanations of the vicious circle phenomenon and were applied to theories of isolation effects. It was concluded that the mechanism involved in other reports of unusual response persistence during extinction by isolates is the result of a failure by isolates to attend to the withdrawal of relevant environmental stimuli. Additionally, data supporting a discrimination explanation of the vicious circle phenomenon were challenged on methodological grounds. It appeared that earlier researchers had failed to find a consistent main effect of shock intensity because they exceeded tetanization levels with their chosen shock intensities.

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First Committee Member (Chair)

John Paul Gluck Jr.

Second Committee Member

Sidney Rosenblum

Third Committee Member

Harold D. Delaney



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Psychology Commons