Pain Acceptance Training in Patients Experiencing Emotional Distress and Somatic Symptoms: Examination of Dialectical Thinking as a Mediating Factor

Measured by using the Patient Health Questionnaire-9 (PHQ-9). A self-report questionnaire for adults, the purpose of which is to examine the presence and severity of clinical depression23. The questionnaire includes 9 items that are a list of major depressive symptoms, according to the DSM. For each item, the examinee is asked to estimate how often he was bothered by the statement described in the item during the last two weeks, on a 4-point Likert scale of 3 (0 - not at all, 3 - almost every day). In addition, the examinee was asked how much the problems he reported made it difficult for him to do his job, take care of things at home or get along with others. This last item is important and significant to assess the degree of distress caused to a person by his symptoms, and the score in it is closely related to the degree of the person's quality of life.

Measured by using the Generalized Anxiety Disorder 7-Item Scale (GAD-7). A self-report questionnaire with 7 items describing anxiety symptoms. In this questionnaire, the participant is asked to describe how well each statement describes his situation in the past two weeks, on a 4-point Likert scale (0 - not at all, 3 - almost every day). The questionnaire is acceptable for use for research and clinical purposes to detect anxiety symptoms in general, and general anxiety symptoms in particular, both in the general population and in clinical populations. The questionnaire has good psychometric properties including high internal reliability (Cronbach's alpha index = 0.89), and high validity indices.

Measured by using the Dichotomous Thinking Inventory (DTI), a self-report measure used to assess a black-and-white cognitive thinking style or worldview. The questionnaire assesses an individual's dichotomous thinking style in a general setting by measuring the degree of positive view of dichotomy, such as dichotomous thinking being better than other thinking styles and dichotomy being consequent, deserved, and worthy. The DTI has 15 items scored on a 6-point scale ranging from 1 = disagree strongly to 6 = agree strongly. The DTI has 3 components: preference for dichotomy, dichotomous beliefs, and profit-and-loss thinking.

Measured by evaluating daily pain ratings in the two weeks during the intervention period, via online questionnaire, on a scale ranging from 0 -not pain at all, to 100 - maximum pain they can imagine. Further, evaluating who much the pain interfered with daily activities, on a scale ranging from 0 - not at all, to 100 - interfered with all daily tasks.

Measured by Patient's global impression of change (PGIC) scale. Patients rate their improvement on a seven-point scale, where 0 equals "very much worse" and 6 equals "very much improved". This scale will be asked only in the last session, at the end of the intervention period. Patients themselves make a subjective judgment about the meaning of the change to them following treatment, this scale is often taken as the external criterion or "gold standard" of clinically important change. However, this method, by itself, does not indicate what has improved.

Measured by using the Pain catastrophizing scale (PCS). The PCS contains 13 items that measure catastrophic thoughts about pain in both clinical and non-clinical samples. Participants reflect on past painful experiences and indicate on a 5-point scale ranging from zero ("not at all") to four ("always") the degree to which they experience each of the 13 thoughts or feelings during the experience of a pain (i.e. "When I'm in pain it's terrible and I think it's never going to get any better"). Research has shown that the PCS is valid and reliable

Measured by the Dialectical Self Scale (DSS), a validated and reliable measure that assesses dialectical self-esteem as related to self-perception. The DSS is a 32-item instrument using a 7-point Likert scale ranging from strongly disagree to strongly agree to measure the perception of dialecticism. Sixteen items describe scenarios that are inconsistent with naive dialecticism which are reverse-scored to determine a dialectical self-esteem rating, with high scores representing greater degrees of dialecticism (i.e. individuals who are "more dialectically oriented").

Measured by using the Cold Pressor Task (CPT), which consists tub containing cold water. Water's temperature will be kept at 10-12°C, to create a moderate pain sensation. This is a usual temperature range when studying pain, and based on our vast experience with this task it appropriate for the present experiment. Participants will be seated in a chair adjacent to the container and asked to immerse their non-dominant hand into the tab for as long as they feel able to do so. Maximum duration of immersion will be five minutes.

The outcome measure will be pain threshold, which indicates the number of seconds from immersion in the tub that the participant first reported feeling pain. Threshold is a behavioral index of hypervigilance towards the pain experienced in the cold pressure. The second outcome measure will be pain tolerance, which indicates the number of seconds from immersion in the tank that the participant can tolerate the pain

Measured by the a computerized version of the emotional modification of the perceptual load paradigm. In this task, participants are required to indicate whether a target letter (X or N) appears on the screen, by responding to the corresponding letter on the keyboard.

The task contains two perceptual load conditions, low and high, which are determined by the number of distracting letters appearing alongside the target letter. In the low load condition, one distracting letter appears on the screen alongside the target letter, whereas in the high load condition, four distracting letters appear on the screen together with the target letter. The distracting letters are chosen randomly from the letters K, H, V, Z, or W. The target and distracting letters appear randomly in six possible locations that create an imaginary circle at the center of the screen. The distracting pictures can be either neutral or pain-related one.

Measured by evaluating daily anxiety, distress and mood ratings in the two weeks during the intervention period, via online questionnaires, asking how much the participants felt one of these feeling today on a scale ranging from 0 (not at all) to 100 (all the time).