Updating vs. Exposure to Modify Responses to Traumatic Stimuli
: An Experimental Study

Student thesis: Doctoral ThesisDoctor of Clinical Psychology


Re-experiencing symptoms are a hallmark feature of Post-Traumatic Stress Disorder (PTSD). They are postulated to result from the way in which a trauma memory is encoded, organised and retrieved (e.g. Ehlers, Hackmann, & Michael, 2004). Research has illustrated the effectiveness of exposure therapy (Foa et al., 1991) and Trauma-Focused Cognitive Behavioural Therapy (NICE, 2005) in the treatment of chronic PTSD, yet evidence for early intervention has been mixed. Reducing the fear response is a central aim in therapies for PTSD. Studies have shown that the fear response can be conditioned in humans in the laboratory, that it can return following extinction and that it can be prevented from returning (Schiller et al., 2008, 2010). This analogue study investigated methods to reduce the conditioned fear response, intrusion frequency and PTSD symptoms after viewing trauma films. The research used an experimental design that combined conditioning and trauma film paradigms. All participants underwent the same fear conditioning paradigm where trauma film stimuli (unconditioned stimuli) were paired with neutral stimuli (conditioned stimuli). Participants were randomly allocated to one of three US devaluation groups: ‘update’, ‘exposure’ and ‘neutral’. Exposure and updating techniques are frequently used as components of psychological therapy for PTSD but their relative effectiveness is unclear. This study aimed to compare the effects of updating the meaning of the trauma films (update group), further exposure to the trauma films (exposure group) and viewing non-traumatic films of related content (neutral group) on the reduction of the conditioned fear response and analogue PTSD symptoms. This study also investigated whether individual differences in fear conditioning are associated with the development of PTSD symptomatology. Overall, the findings suggest that adding a cognitive update to a US devaluation process significantly reduces subjective distress ratings to fear conditioned stimuli as well as intrusion frequency and PTSD symptoms. In this study, having a larger conditioned acquisition response predicted higher intrusion frequency and distress and more PTSD symptoms. However, in contrast to the hypotheses, adding a cognitive update to US devaluation increased skin conductance response to the conditioned stimulus compared to further exposure to the films. Theoretical and clinical implications are discussed as well as limitations and avenues for future research.
Date of Award2013
Original languageEnglish
Awarding Institution
  • King's College London
SupervisorJennifer Wild (Supervisor) & Patrick Smith (Supervisor)

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