Preference for information about intensity of signaled tailshock

Three experiments are reported which were designed to demonstrate preference for signaled shock and to delineate the roles of the preparatory-response, information-seeking, and signaled-safety hypotheses of this phenomenon. Experiment 1 demonstrated a preference for a signal-tailshock condition over a tailshock-signal condition in a shuttlebox. In Experiment 3, rats were exposed to signaled tailshock of two intensities in both compartments of the shuttlebox, but in one compartment the signals provided information about the intensity of the impending tailshock, whereas in the other compartment the signals did not. The tailshock intensities were .6 and 1.3 mA for one group and .6 and 1.8 mA for a second group. Experiment 2 assured that even the smaller intensity difference was readily discriminable. For Group .6-1.8 a significant preference for the condition in which the signals predicted the intensity of the impending tailshocks was obtained, but no preference for either condition was found for Group .6-1.3. As signaled safety was equated in the two compartments of Experiment 3, the observed preference cannot be accounted for by the signaled-safety hypothesis. Information seeking cannot explain the lack of preference in Group .6-1.3 as the difference between those two intensities was proven discriminable in Experiment 2. Assuming that sufficient differences in shock intensity yield different preparatory responses, the present results are compatible with the preparatory-response hypothesis and suggest that preparatory responding plays a role in producing the preference for signaled shock.