The Role of Simulation in Imagery Rescripting for Posttraumatic Stress Disorder: A Single Case Series

Little is known about the mechanisms for change involved in Imagery Rescripting (ImRs), an image-based therapy technique used to target intrusive imagery in post-traumatic stress disorder (PTSD) by imaging alternative endings to traumatic events (Arntz, 2012). The aim of this study was to explore the role of simulation as a mechanism for change in ImRs through the use of a single-case experimental design (SCED) and coding. Both ImRs and simulation involve the mental construction of a hypothetical event that has not actually happened. Seven individual cases were followed for the duration of rescripting of one image. It was hypothesised that those with well-simulated rescripts would experience greater reductions in image intrusiveness than those with less well-simulated rescripts. Effective ImRs was also hypothesised to link with greater reductions in counterfactual thinking (and associated frequency/distress) and an increase in global meaning, with high levels of simulation expected to play a role in both of these links. Sessions were also coded for other potential mechanisms such as activation of thoughts/emotions and level of belief in the rescript. Coding results from session recordings and patterns of outcome measures from the seven cases were explored at group and individual levels. Due to the small sample size and the observational nature of much of the analyses, results were tentative in nature. However, group and individual analyses offered initial support for the idea that higher levels of simulation were followed by greater reductions in symptoms. Additional factors, especially intensity of thoughts/emotions related to original and new imagery elements, level of cognitive and emotional shift and belief in the resultant rescript, were also identified. Potential mechanisms of action between these factors are discussed. Offering initial support for the second hypothesis, participants who experienced the greatest change in symptom severity also experienced the greatest changes in counterfactual thinking, and very tentative support suggests that this was linked to simulation levels. No support was found for the third hypothesis, as symptom severity reduction was not linked to increases in global meaning. Potential implications of these findings and suggestions for future research are discussed.