The effect of an aversive event on the return of fear.

An experiment on the return-of-fear (ROF) was carried out on 40 snake- or spider-phobic subjects in order to determine whether an arousing event that occurs shortly before retest influences the magnitude of the ROF. Additionally, we attempted to produce a reinstatement of fear by introducing an unrelated aversive event (shock) after the fear had been reduced. The arousal manipulation successfully increased subjective arousal but not heartrate responsiveness. The increases in subjective arousal were not followed by increases in ROF, and the attempt to produce a reinstatement of fear did not succeed. A significant correlation between speed of fear-reduction and ROF was obtained.