Comparison of Experimental Pain Modulation by Hypnosis, Virtual Reality and Virtual Reality Hypnosis in Healthy...

Hypnosis (H) and virtual reality (VR) are effective behavioural interventions to influence acute pain perception. Hypnotic suggestions have also been shown to modulate the nociceptive flexion reflex (NFR), suggesting the activation of descending modulatory mechanisms affecting spinal nociceptive activity. The combination of these techniques, virtual reality hypnosis (VRH), may reduce pain, but research on their comparative efficacy and mechanisms requires further experimental investigation. This study compared the effects of relaxation hypnosis, VR and VRH on pain perception and nociceptive physiological responses.

Twenty-four healthy participants were tested at baseline followed by three experimental conditions (relaxation hypnosis, VR, VRH) in a counterbalanced order. Pain intensity and unpleasantness, as well as NFR amplitude evoked by noxious transcutaneous electrical stimulation, were measured. Bayesian statistics assessed evidence for analgesic effects on each variable.

The strength of evidence in favour of our hypotheses was categorised as follow: BF = 1-3: anecdotal evidence; BF = 3-10: moderate evidence and BF > 10: strong evidence. For NFR values, Bayesian paired-sample T-tests provided anecdotal support for the efficacy of relaxation hypnosis (BF + 0 = 2.11) and stronger evidence for VR (BF + 0 = 10.94) and VRH (BF + 0 = 14). For pain intensity, moderate evidence supported reductions with relaxation hypnosis (BF + 0 = 9.18), while strong evidence was found for VR (BF + 0 = 27.99) and low to moderate for VRH (BF + 0 = 5.88). Similarly, unpleasantness showed anecdotal reduction with hypnosis (BF + 0 = 1.9), and moderate evidence supported VR (BF + 0 = 4.86) and VRH (BF + 0 = 7.18). Across all measures, no significant differences were found between hypnosis, VR and VRH.

These findings suggest that these techniques did not differentially affect NFR, pain intensity, or unpleasantness.

The strength of this fundamental study is to directly compare hypnosis, VR, and VRH on both pain perception and physiological responses. It shows that VR alone is effective, while adding hypnosis does not always lead to better results and the combination could even create interference in some cases. This article helps to nuance the existing literature and common assumptions about the tool's use. These findings help clarify how VRH works and to propose guidance for clinical practices and further VRH development.