Posttraumatic Stress Disorder (PTSD) is a highly prevalent and debilitating disorder. The first line treatment for PTSD is prolonged exposure (PE) therapy. Inhibitory learning theory proposes...Show morePosttraumatic Stress Disorder (PTSD) is a highly prevalent and debilitating disorder. The first line treatment for PTSD is prolonged exposure (PE) therapy. Inhibitory learning theory proposes threat expectancy violation as a strategy to enhance effectiveness of PE. No standardized instrument for the assessment of threat expectancies is currently available. The aim of the current study was to assess the psychometric properties of the TREE, a novel instrument to assess threat expectancies. The reliability and factor structure of the TREE were assessed in a non-clinical sample of 158 trauma-exposed individuals. The TREE showed excellent reliability and was found to consist of four subscales: 1. Fear of dying/losing control, 2. Externalizing symptoms, 3. Negative evaluation, 4. Internalizing symptoms. The reliability of all subscales was good with an internal consistency ranging from .75 to .85. The TREE allows clinicians to tailor exposure sessions to the individual threat appraisal profile of their patients. Furthermore, by making threat expectancies explicit, it can aid in further understanding the mechanisms underlying PE. The factor structure of the TREE should be confirmed and its generalizability to the non-clinical and clinical population should be corroborated in future research.Show less
After decades of widely studying fear habituation as a mechanism of change in exposure therapy, the focus seems to be shifting towards harm expectancy violation through which new non-threat...Show moreAfter decades of widely studying fear habituation as a mechanism of change in exposure therapy, the focus seems to be shifting towards harm expectancy violation through which new non-threat associations are acquired. Expectancy violation has found a more consistent support in modern literature, but it has not yet been sufficiently investigated as a mechanism or a marker of change in exposure, when treating post-traumatic stress disorder (PTSD). Understanding what drives change could facilitate designing effective interventions that would improve exposure outcome, and high dropout or non-response rates, that are often accompanying PTSD treatment. The aim of this master thesis was to explore the relationship between harm expectancy violation, within and between the first two exposure sessions, and change in PTSD symptoms, after these two sessions and post-treatment, as measured by PCL. To put these relationships into perspective, predictive value of fear habituation indices in relation to the outcome was also assessed; and further, it was evaluated whether expectancy violation and habituation act as separate constructs when standing together. Results have shown that early indices of between-session expectancy violation and within-session fear habituation had a significant, though weak, relationship to early treatment outcome, while acting as separate predictors. However, this study has not found any of the early indices of expectancy violation or fear habituation to be indicative of the end-of-treatment outcome. Furthermore, it points to limitations regarding measuring harm expectancies and provides recommendations for future research.Show less
