The development of the ‘Forms of Responding to Self-Critical Thoughts Scale’ (FoReST)

Background: Self–critical thoughts are a feature of many mental health problems. Adopting a psychologically flexible response to thoughts has been highlighted as a key determinant of wellbeing. But, the measurement of psychological flexibility (PF) in relation to self-critical thoughts is under-developed. This paper reports on the development of the Forms of Responding to Self-Critical Thoughts Scale (FoReST). Method: Study One involved the development and exploratory factor analysis of the FoReST in a convenience sample of 253 non-clinical adults. Study Two was a confirmatory factor analysis study of the FoReST in a sample of 110 University students. Study 3 explored the convergent and concurrent validity of the FoReST by examining associations with measures of similar constructs (PF, self-compassion, self-criticism) and relevant mental health measures (anxiety, depression, distress). Study 3 also explored the FoReST's incremental validity for predicting depression and anxiety levels beyond an established measure of self-critical thinking. Results: In Study One, exploratory factor analysis produced a 9-item/2-factor solution (unworkable action and mindful acceptance). The measure demonstrated good internal consistency. In Study 2, the confirmatory factor analysis also indicated a 2-factor model (unworkable action and mindful acceptance) and overall internal consistency that was excellent. In Study Three, the FoReST demonstrated high convergent validity with similar measures, and good concurrent validity with mental health outcomes. Analyses also indicted good incremental validity for the FoReST for predicting HADS depression and anxiety scores. Conclusions: The FoReST appears to be a psychometrically sound measure suitable for measuring change processes in third wave therapies such as Acceptance and Commitment Therapy, Mindfulness-based Interventions and Compassion Focused therapy