Safety Behavior After Extinction Triggers a Return of Threat Expectancy

Safety behavior is involved in the maintenance of anxiety disorders, presumably because it prevents the violation of negative expectancies. Recent research showed that safety behavior is resistant to fear extinction. This fear conditioning study investigated whether safety behavior after fear extinction triggers a return of fear in healthy participants. Participants learned that two stimuli (A and C) were followed by an aversive loud noise ("threat"), and one stimulus (B) was not. Participants then learned to use safety behavior that prevented the loud noise. Next, A and C were no longer followed by the loud noise, which typically led to extinction of threat expectancy. Safety behavior then became available again for C, but not for A and B. All participants used safety behavior on these C trials. In a final test phase, A, B, and C were presented once without the availability to use safety behavior. At each stimulus presentation, participants rated threat expectancy by indicating to what extent they expected that the loud noise would follow. Compared with the last extinction trial, threat expectancy increased for C in the test phase, whereas it did not increase for A and B. Hence, safety behavior after the extinction of classically conditioned fear caused a partial return of fear. The findings suggest that safety behavior may be involved in relapse after exposure-based therapy for anxiety disorders.