Preexposing a stimulus may enhance its subsequent extinction

Abstract

Extinction, the repeated exposure to a stimulus following conditioning results in decreased conditioned responding (i.e., conditioned fear), has long been used as a therapeutic treatment to attenuate various anxiety disorders, such as phobias and post-traumatic stress disorder (PTSD). But extinction is not the only exposure treatment that can attenuate conditioned fear responses. Exposure to the CS prior to conditioning (CS preexposure) is also known to retard acquisition of conditioned fear. Thus, it seems logical to expect that combining CS preexposure and CS postexposure (extinction) treatments should magnify each treatment’s response-attenuating properties. However, previous research suggests otherwise. In three experiments using rat subjects, the present research assessed the combined effects of CS preexposure and extinction, varying the time of introduction of each exposure treatment with respect to conditioning. Extinction performed either immediately or with a delay after conditioning did not differ in the amount of recovery of conditioned fear when the treatments were combined. However, preexposure occurring immediately prior to conditioning (but not long before conditioning) attenuated spontaneous recovery of subsequent extinction, even if few CS preexposures were provided. These results suggest that a combination of CS preexposure and extinction can provide benefits for the long-term attenuation of fear.