In any aversive conditioning procedure, when an aversive stimulus is paired with a nominal CS, it is inevitable that other stimuli present in the conditioning environment should also become aversive. Although the conditioning of fear to the environment has seldom been studied explicitly, there are reasons to believe that certain parameters affect specific fear and environmental fear quite differently. Ethyl alcohol, in particular, may produce dissimilar effects on the two fears. If so, these differences would help to explain certain inconsistent findings reported with alcohol. A conditioned suppression procedure was used to test the hypothesis that alcohol differentially affects specific and environmental fear. Sixty-four rats which had learned to press a lever for water reinforcement received pairings of a warning tone and electric footshock. In addition to the usual ratio of suppression of responding in the presence of the CS, a second index of response suppression in the conditioning environment with the tone absent was calculated. It was found that alcohol produced little effect on the index of specific fear, but that suppression to environmental stimuli was significantly attenuated (p < .05) at the two highest of the three shock intensities employed. Ss were then given six sessions in the conditioning chamber with neither tone nor shock present. For six additional sessions, tones were presented as in conditioning, but shock was not administered. Alcohol appeared to hasten the extinction of suppression to both the CS and environmental stimuli, but the effects did not attain statistical significance. For 16 Ss, at the end of regular conditioning trials, drug and no drug states were reversed three times during continued tone-shock pairings. Alcohol was found to produce a strong, but transitory, attenuation of environmental suppression, while suppression to the CS was relatively unaffected by the changes in drug state. Alcohol was clearly shown to produce a lessening of environmental fear, while fear of a specific stimulus was little affected. The effects on the environmental fear were, however, transitory in nature, and were not discernable when Ss were later tested in the absence of the drug. The findings are consistent with explanations of drinking behavior which emphasize the fear-reducing properties of alcohol. However, they suggest that these explanations should be restricted to the reduction of diffuse anxiety and not of specific fears.
Lawrence L. Dickerson (Wed,) studied this question.