0-phobia: towards a virtual cure for specific phobias

The main study parameters are the post-test differences in anxiety symptoms between the experimental and control condition, and follow-up differences in anxiety symptoms between baseline and follow-up in the experimental condition.
The main parameter will be the 20-item anxiety subscale of the Acrophobia Questionnaire (AQ, Cohen; 1977). The anxiety subscale has a 7-point Likert scale (‘not anxious’ to ‘extremely anxious’), total score 0-120.

Secondary parameters are:

• The Attitudes Towards Heights Questionnaire (ATHQ; originally Abelson & Curtis, 1989, with minor modifications to the wording reported in Coehlo, Santos, Silvério, & Silva, 2006) is a 6-item measure in which individuals read pairs of dichotomous adjectives describing ways people may feel about heights (e.g., “Good/Bad,” “Safe/Dangerous”), and rate how they feel about elevated places on a scale of 0 (which corresponds with the first adjective) to 10 (which corresponds with the second adjective). The ATHQ has been used in several height fear treatment studies and is sensitive to treatment effects (Coehlo et al., 2006; Emmelkamp, Bruynzeel, Drost, & van der Mast, 2001). Reliability is good (Steinman & Teachman, 2014).

• Beck Anxiety Inventory (BAI; Beck et al., 1988) is a 21-item self-report questionnaire assessing symptoms of anxiety. Patients record how much they have been bothered by each symptom during the past week, including the day the questionnaire is administered. Each item is rated on a 4-point Likert scale ranging from 0 = not at all to 3 = severely: I could barely stand it. The total score ranges from 0 to 63. The following guidelines are recommended for the interpretation of scores: 0–9, normal or no anxiety; 10–18, mild to moderate anxiety; 19–29, moderate to severe anxiety; and 30–63, severe anxiety. Internal consistency is high (0.90-0.94) and convergent validity is good (Brown et al., 1997).

• System Usability Scale (SUS; Bangor et al., 2008): 10 items about user friendliness of the app. The SUS is composed of 10 statements that are scored on a 5-point scale of strength of agreement. Final scores for the SUS can range from 0 to 100, where higher scores indicate better usability. This means that products that are at least passable have SUS scores above 70, with better products scoring in the high 70s to upper 80s. Truly superior products score better than 90. Products with scores less than 70 should be considered candidates for increased scrutiny and continued improvement and should be judged to be marginal at best. Reliability is good (Bangor et al. 2008). This questionnaire will be completed at post-test.

• Igroup Presence Questionnaire (IPQ; Schubert, Friedmann and Regenbrecht 2001), a 14-item questionnaire which assess realism and “presence” in the VR environment. Each of the items has five response categories from fully disagree (1) to fully agree (5). Chronbach`s alpha is good (α = .73). This questionnaire along with some open questions about user experience of the VR environment will be completed at post-test.

• Mastery (Pearlin Mastery Scale; Pearlin and Schooler, 1978), 7 items to measure self-experienced control over a situation. Each of the 7 items has five response categories from 1 (totally disagree) to 5 (totally agree). The questionnaire has good psychometric properties. (Pearlin & Schooler, 1978). This questionnaire will be completed at baseline, post-test and follow-up.

• The nine-item mood module of the Patient Health Questionnaire (PHQ-9 ; Kroenke et al, 2007) is used to screen subjects with depressive disorders. The 9 items are each scored 0–3, total score range is 0–27. In a review of Wittkampf et al. (Wittkampf et al., 2007), a sensitivity of 0.77 (0.71–0.84) and a specificity of 0.94 (0.90–0.97) was found for the PHQ-9. This questionnaire will be completed at baseline, post-test and follow-up.

• One question about suicidal ideation from the Screening Questionnaire (Gega et al., 2005) and translated for the Dutch population in the WSQ (Donker et al., 2009): “has the idea of harming yourself, or taking your own life, recently come into your mind?” Answer options are” (1) Definitely not; (2) I seriously considered it but I stopped myself”; (3) “I would do it given the opportunity

• Assessment of current anxiety level directly before and after exposure