Blurring Aversive Memory: Exploring a Novel Route to Fear Reduction

Abstract

Treatment of pathological fear typically involves exposure to the feared stimulus. This procedure is effective in reducing fear in the short term. However, many patients relapse, i.e. show a return of fear. The present thesis explored a novel route to counter the renewal of fear. Previous research has shown that exposure-based treatments result in inhibition of the fear memory (i.e., the association between a stimulus and its catastrophic consequence), and that a weakening of the fear memory is associated with a reduction in fear renewal. That is, if a person will come to evaluate the fear memory less negatively, then its (re)activation evokes a less intense fear response. Another line of previous research has shown that making eye movements during recall of an aversive memory causes a less negative evaluation of that memory. Specifically, the ‘dual task’ reduces memory vividness and emotionality, and this technique is widely used in Eye Movement Desensitization and Reprocessing (EMDR) therapy for posttraumatic stress disorder. Hence, we hypothesized that making eye movements during recall of a fear memory results in fear renewal attenuation. Multiple laboratory experiments in healthy participants were conducted to test these hypotheses. Findings are that making eye movements during recall of an aversive memory reduces the self-reported vividness and emotionality of the memory, and that these reductions are maintained at a 24 hr follow-up test. Next, we showed that the dual task is associated with lower levels of self-reported fear and less return of fear after extinction. We further elucidated that whereas fear reduction via violation of threat expectancies is associated with fear renewal, fear reduction via a reevaluation of the catastrophic outcome is not. Given that the eye movement intervention primarily focusses on the latter pathway, this suggests further that the dual task is a potentially useful technique for the attenuation of fear renewal. The results of a final experiment suggest that therapists should be careful when determining what memory features are recalled during the eye movement intervention. For example, after a violent attack, a person may recall the moment a knife was put to the neck, but also contextual stimuli such as the appearance of the perpetrator. Findings are that the blurring of a danger cue representation (e.g., the face of a perpetrator) reduces discriminability between this danger cue and perceptually similar stimuli (e.g., faces of other persons), and thereby increases the generalization of fearful responding. To summarize, the laboratory experiments reported in this thesis provide preliminary support suggesting that blurring of aversive memory by dual-tasking may provide a novel route to the reduction of fear renewal.