Abstract:

Fear is an emotional response that rapidly serves humans and animals by preparing them for threats and danger. However, excessive fear is a hallmark of various debilitating anxiety disorders. Ways in which to erase or decrease fear have recently gained considerable fundamental and applied research interest. Unfortunately, numerous prior experiments have found that an acquired fear is difficult to disrupt and always eventually recovers with the passage of time following intervention in the absence of any further training. In recent years, because of the fact that humans voluntarily monitor and regulate their emotional states during stressful situations, interest in modulating the fear response through emotional regulation has rapidly increased. Emotional regulation strategies, such as cognitive reappraisal, have been shown to effectively decrease subjective ratings of emotion, heart rate, and skin conductance responses (SCRs) to negative emotional stimuli. Cognitive reappraisal also robustly reduces the conditioned fear response. However, the long-term effects of reappraisal on the fear response are unknown. The aim of the present study was to evaluate the effects of cognitive reappraisal on human fear acquisition and fear expression.We also evaluated whether reappraisal can inhibit conditioned fear in the long term by testing spontaneous fear recovery. In experiment 1, a sample of 30 right-handed college students (15 males and 15 females) underwent training using a partial reinforcement fear conditioning paradigm.The paradigm consisted of three stages: acquisition (day1), expression test (day2), and spontaneous recovery test (day32). One day1, the participants were randomly divided into two groups and instructed to perform reappraisal or attend to the stimulus when it was presented. For cognitive reappraisal training in the reappraisal group,the participants were taught to regulate their fear responses to the aversive stimulus. Fear acquisition training followed reappraisal training 5 min later, in which the participants learned that one colored square (e.g., blue, conditioned stimulus [CS+]) predicted a loud white noise (unconditioned stimulus [US]) and another colored square (e.g., yellow, [CS−]) was presented alone. In the acquisition process, the participants in the reappraisal group had to use the newly acquired regulation skills, and the participants in the attend group were asked to view the stimulus and attend to their natural feelings when the CS was presented. The next day, fear expression was tested by presenting the CS without the US. Thirty days later, a spontaneous fear recovery test was conducted similarly to the fear expression test. Experiment 2 included 28 participants (13 males and 15 females). The design of this experiment was the same as experiment 1, with the exception of the stage that reappraisal involved. In experiment 2, reappraisal was conducted in the fear expression test stage on day 2. In all stages of the two experiments, differential SCRs to the CS+ minus SCRs to the CS− served as an index of conditioned fear levels and were acquired from the participant’s middle phalanges of the second and third fingers on the left hand using the BIOPAC Systems skin conductance module. In experiment 1, reappraisal effectively decreased SCRs during fear acquisition with the CS+ relative to the CS−. Consistent with fear acquisition, 24h and 30 days later, the reappraisal group also exhibited significant lower conditioned fear levels in the fear expression and spontaneous fear recovery tests. In experiment 2, the reappraisal and attend groups exhibited equivalent levels of conditioned fear on day 1. However, reappraisal significantly decreased levels of conditioned fear in test 1. More importantly, compared with the attend group, reappraisal successfully inhibited the spontaneous recovery of conditioned fear 30 days later. The present results support the critical contribution of cognitive reappraisal in fear conditioning and in fear expression tests with regard to inhibiting the conditioned fear response. Importantly, these inhibitory effects lasted for at least 1 month. These parallel results suggest that cognitive reappraisal may be able to disrupt memory formation during conditioning or erase conditioned fear memory that is already consolidated. Our results are consistent with clinical findings, in which emotional cognitive reappraisal interventions are an effective treatment for patients with anxiety or depression disorders. Therefore, the use of cognitive reappraisal may be an effective tool for suppressing fear responses to traumatic events and prevent the development of stress-related psychological illness.

Key words: cognitive reappraisal, acquisition, expression, spontaneous recovery, fear conditioning