Hypnosis and virtual reality are potential tools in treating acute pain. Nevertheless, the neurophysiological correlates of such tools used together, i.e. 'virtual reality hypnosis' (VRH) (Patterson et al., 2004) remain mostly understudied. This study aims to improve our knowledge and understanding of the dissociation (i.e., a mental separation of components of behaviours that normally would be processed together) occurring during VRH. This is a randomized controlled study that will be conducted on healthy participants. As the final goal is to propose such a tool in the clinical context, a clinical application will also be carried out subsequently.

Thus the principal outcome is to study dissociation in the context of VRH from a behavioral and neurophysiological point of view.

Secondary objectives aim at identifying factors that influence the dissociative effect seen in VRH, as well as measuring traits of hypnotisability, absorption, immersive abilities, dissociation trait and state, pain, and anxiety levels that might impact the effectiveness of such a tool.

The protocol will follow the following steps:

1. Before the experiment:

   • A medical screening of the medical history and of any concomitant medications will be performed to eligibility.
   • The 6-item Elkins Hypnotisability Scale (EHS) will be used to assess participant hypnotisability.
   • Questionnaire sur la Propension à l'Immersion (QPI) will be used to assess participant immersion tendency.

2. Experimental session: Cross-over and within-participant control design i. Visual Analogue Scale (VAS) :

   • Anxiety.
   • Pain. ii. EEG Resting-state (5-Min.). iii. EEG VRH or EEG Hypnosis alone (HYP) (15-Min.). iv. Adverse Events (AE) during the protocol will be recorded. v. Narrative recording. vi. VAS :
   • Dissociation
   • Absorption
   • Pain
   • Anxiety
   • Arousal/wakefulness
   • Automaticity vii. Time perception (open question) viii. CyberSickness (CSQ) (only if VRH) ix. Presence Questionnaire x. Satisfaction questionnaire xi. Washout Phase (30-Min.) during which we will administer :
   • Six-item State-Trait Anxiety Inventory (STAI-6) .
   • Tellegen Absorption Scale .
   • Dissociative Experience Scales (DES) . xii. VAS:
   • Anxiety
   • Pain xiv. Adverse Events during the protocol will be recorded. xv. Narrative recording. xvi. EEG HYP or EEG VRH Phase (15-Min.). xvii. VAS:
   • Dissociation
   • Absorption
   • Pain
   • Anxiety
   • Arousal/wakefulness
   • Time perception xviii. CSQ (only if VRH) xix. Presence Questionnaire. xx. Satisfaction Questionnaire .

Inclusion Criteria: Subject more than 18 years old and equal or less than 65 years old.

Exclusion Criteria:

1. Low auditory and/or visual acuity precludes the use of the device.
2. Head or face wounds precluding the use of the device.
3. Schizophrenia, dissociative disorder or any other psychiatric disorder.
4. Non-proficiency in French (Research language).
5. Patient under 18 years old.
6. Phobia of deep water.
7. Allergy to cutaneous electrodes.
8. Chronic pain and/or chronic analgesics consumption.
9. Medication affecting the autonomic nervous system.
10. Dizziness.

Methodology of virtual reality hypnosis prevents masking the participants and the experimenter.