RCT Protocol for 'OverThinking': A Mobile EMI for Reducing Experiential Avoidance

Perseverative thinking as measured by the Perseverative Thinking Questionnaire (PTQ)

The PTQ is a 15-item self-report measure, which assesses the main characteristics of repetitive negative thinking (1: core features - 9 items, 2: unproductiveness - 3 items, 3: capturing mental capacity - 3 items. Responses are recorded on a scale of '0' ('never') to '4' ('almost always').

Beliefs about emotions as measured by the Emotion Beliefs Questionnaire EBQ

The EBQ is a 16-item self-report questionnaire intended to measure the controllability of emotions and respondent beliefs about the usefulness of emotions. Respondents answer using a 7-point Likert scale ranging from 1 (totally disagree) to 7 (totally agree), with high scores indicating a belief that emotions are uncontrollable and/or useless.

Metacognitive beliefs about rumination using PBRS/NBRS

This is comprised of two sub-scales (positive beliefs: 9-items, negative beliefs: 13-items) measuring metacognitive beliefs of depressive rumination. Respondents rate the extent to which they agree with each of the items using a 4-point Likert-type scale ranging from 1 (do not agree) to 4 (agree very much), with higher scores on each subscale indicating greater positive/negative belief accordingly.

Hospital Anxiety and Depression Scale (HADS)

A measure of possible and probable presence of anxiety disorders and depression, comprising seven items for depression and seven items for anxiety. Respondents rate on a scale of 0-3 for each item, with higher total scores for each subdomain (anxiety, depression) indicating greater presence of the disorder. Thresholds are provided for determining the clinical presence of disorder as follows: 0-7 = Normal, 8-10 = Borderline abnormal (borderline case),11-21 = Abnormal (case)

Time spent using the application

The application has been designed to record the amount of time a user is active (and in which in-app exercises). This data is stored remotely and securely via Firebase. This data is password protected and access is limited to the individuals on the research team.

Ongoing Application Development Feedback (CORTO)

Three items (two quantitative and two qualitative) collected following each in-app exercise, with the aim of providing real-time user-experience data to enable the ongoing development of the app. Items include: 1) Do you like using the application? (1: "not at all", 7: "very much"), 2) How would you rate the difficulty level of using the application? (1: "definitely too easy", 7: "definitely too difficult"), and 3) Would you like to share any thoughts about the app? (open-ended question). Data obtained via CORTO implementation will be coded deductively using the process outlined by Saldana (2016) and using the four categories identified by Lukka et al. (2024) as high-level guidance ((1) contextual use, (2) interaction-elicited emotional experience, (3) usability, and (4) technical issues.), with more detailed coding examined as subdomains.