Exposure to images of post-bushfire disaster impacts fear learning and extinction

Abstract

Exposure to natural disasters, such as bushfires, increases vulnerability for poor psychological outcomes. Large scale reviews have increased our understanding of risk factors associated with disaster related maladjustment, however this relationship remains unclear. This study examined the effect of exposure to resource loss in the post-bushfire disaster environment on fear learning and extinction pathways. Participants (70 adults; 73 % female, 17–58 years of age, M = 23.77, SD = 8.16) were randomly allocated to view scenes depicting post-bushfire resource loss (post-bushfire disaster group) or no disaster (community group) followed by all participants completing a discriminative Pavlovian conditioning task including habituation, conditioning, extinction, and retest phases. During acquisition, one shape (CS+) was paired with an aversive tone as the unconditioned stimulus (UCS) and another shape (CS-) was presented alone, while both CSs were presented alone during extinction and retest phases. Subjective ratings of fear, worry and sadness, were obtained before and after picture viewing and between learning task phases whilst ratings of CS pleasantness and arousal were obtained before and after learning task phases. Skin conductance responses (SCR) were recorded to the CSs during all phases. The post-bushfire disaster group reported more subjective fear, worry and sadness after viewing images relative to the community group. The post-bushfire disaster group also showed significantly larger orienting SCRs to both CSs during acquisition relative to the community group and significantly smaller orienting SCRs to both CSs and undifferentiated anticipatory SCRs during extinction relative to the community group. During retest, the post-bushfire disaster group exhibited significantly larger anticipatory SCRs to both CSs compared to the community group. There were no group differences in between phase ratings of CS+ and CS- unpleasantness and arousal and no group differences in subjective anxiety ratings between learning task phases. Exposure to post-bushfire resource loss may increase fear conditioning and generalisation to safe stimuli, impair safety learning, and increase reactivity when re-exposed to fear stimuli.