Background: The inability to suppress excessive fear or anxiety is a significant clinical problem. In the laboratory, extinction is a preferred method for the study of fear inhibition; however, in this paradigm the same stimulus causes both elicitation (excitation) and inhibition of fear, making it difficult to know whether an experimental manipulation that affects extinction does so by affecting one or both of these processes. For this reason, we sought to develop a behavioral procedure in humans that would render a stimulus primarily inhibitory.
Methods: We adapted a conditional discrimination procedure (AX+/BX-), previously validated in animals, to a human fear-potentiated startle paradigm. Forty-one healthy volunteers were presented with one set of colored lights paired with the delivery of aversive airblasts to the throat (AX+) and a different series of lights presented without airblasts (BX-).
Results: Participants exhibited fear potentiation to AX+, discrimination between AX+ and BX-, and transfer of fear inhibition to A in an AB compound test but not in an AC compound test.
Conclusions: We believe this procedure will advance clinical research on fear disorders, such as posttraumatic stress disorder and phobias, by providing an effective and relatively independent measure of fear potentiation and fear inhibition.