Development of a Protocol for Studying Premature Onset of Fear as a Feature of Pathological Fear: The Effects of Conditional Stimulus Duration and Counting Behavior

We propose that the premature onset of fear responding is a potentially important feature of pathological fear. A behavioral protocol to study the temporal regulation of fear in humans is, however, lacking. The present study aims at developing such a protocol for healthy individuals. To this end, we investigated the effect of conditional stimulus duration (50 seconds or 90 seconds) and the effect of verbal counting during presentation of the conditional stimulus (counting or no counting) in an aversive conditioning paradigm. Results favored training conditions in which participans were asked to count for the duration of the conditional stimulus, regardless of conditional stimulus duration. Under these training conditions, we observed optimal temporal control over the onset of fear. Furthermore, it was shown that intervals followed by an aversive stimulus were retrospectively estimated to have lasted longer than those that were not followed by an aversive stimulus. We argue that the developed protocol may serve as a powerful method to study premature onset of fear responding in future studies.