Hypnosis Induction and Height Experience in VR - Control Group Comparison and Three Sessions

This study attempts to test wether a VR-supported trance induction and a subsequent exposure to altitude in VR with hypnotic suggestions via Audio reduces acrophobia more than a control-group intervention without trance induction. Furthermore the study attempts to test if three sessions of the interventions within three weeks can lead to a stronger reduction of acrophobia than only one session.

Participants will be selected via an online survey according to their score on the Height Interpersonal Questionnaire (HIQ). At the start of the study, participants will be screened by professional clinicians for any mental disorders. In the laboratory they will undergo one of the two interventions in VR (experimental group / control group) and complete questionnaires for three times within three weeks. On a separate day within these three weeks they will be placed in a 30-minute trance to test their suggestibility.

Prior to the measurement, those interested in the study will complete a screening questionnaire on acrophobia (HIQ) online. Besides they will be asked if they ever had negative experiences with VR or hypnosis. Only persons who do not report negative experiences with VR or hypnosis and who attain a HIQ score bigger than 29 will be invited to take part in the study. At the first appointment in the laboratory a screening with SCID questions about disorders that would lead to exclusion is conducted. On the basis of this second screening participants will be admitted to the study. Failure to meet the criteria (see eligibility section) will exclude participants from the study. At the start of the assessment session, participants will complete a sociodemographic questionnaire and again the HIQ.

Participants are randomly assigned to one of the two groups. Based on group affiliation they either undergo a VR-supported trance induction or the same VR-program without the trance induction. Then there is an automatic transition to the altitude confrontation. Both groups receive the same VR altitude confrontation, the only difference is that in the experimental group a tree is presented near the participant whereas in the control group a parasol is presented at the same position. Thus the sentences that refer to the tree are changed in the audio of the control group. The height is increased to a maximum of 60 metres. Participants can stop the experiment at any time by pressing a button on a handheld joystick. During the confrontation, various events (e.g. rising balloons) generate additional altitude cues. The duration of the confrontation is approximately 15 minutes. Subsequently participants complete questionnaires about their fear of heights (HIQ) for a post-measurement of altitude anxiety and about their experience of presence (IPQ) and their experience of hypnotic depth (SSTT). Participants will undergo these questionnaires and the intervention three times within three weeks. On a separate day within these three weeks they will be placed in a 30-minute trance and given the Harvard Group Scale of Hypnotic Susceptibility (HGSHS) to test their suggestibility.

The total time required for the participants ist therefore approximately three hours and 15 minutes.

Eligibility Criteria:
Inclusion Criteria:

* HIQ-Score \> 29
* informed consent

Exclusion Criteria:

* Negative previous experience with hypnosis
* Negative previous experience with virtual reality
* Mental illness (psychosis, post-traumatic stress disorder and/or personality disorder)
* neurological disease
* Acute or chronic disease (also anamnestic) that may affect brain metabolism:
* pre-existing diabetes mellitus (E10-E14 according to ICD-10)
* Renal insufficiency from stage 3 of the Kidney Disease Outcomes Quality Initiative
* Uncontrolled hypertension (I10.x according to ICD-10)
* Moderate or severe traumatic brain injury (GCS 3-12), or traumatic brain injury 2nd or 3rd degree with loss of consciousness of \> 30 minutes.