Manipulation of the Apparatus and Response Context may Reduce the US Pre-Exposure Interference Effect

In two experiments, we investigated whether manipulations of associations formed between the context and unconditioned stimulus (US) during exposure would reduce the retardation of future conditioning produced by exposure to the US. In the first experiment, we found that extinguishing the context reduced fear of the context and partially attenuated interference with future conditioning. This attenuation was only transient and there was considerable interference which was unaffected by extinction. In the second experiment, we found that signalling the US during pre-exposure which was carried out off-baseline did not reduce interference when conditioning was also carried out off-baseline. However, signalling the US did reduce interference when conditioning was subsequently continued on-baseline. These results suggest that although the US interference effect is partly mediated by conditioning of the context, it may also depend on learning about the unpredictability of the US during exposure, and some long-term, perhaps context specific, adaption-like mechanism.