Enhancement of suggestibility and imaginative ability with nitrous oxide.
BACKGROUND
Imaginative suggestibility, a trait closely related to hypnotic suggestibility, is modifiable under some circumstances. Nitrous oxide (laughing gas) is commonly used for sedation in dentistry and is reported to be more effective when combined with appropriate suggestions.


OBJECTIVE
The aim of this study was to determine whether nitrous oxide inhalation alters imaginative suggestibility and imagery vividness.


METHODS
Thirty participants were tested twice in a within-subjects design, once during inhalation of 25% nitrous oxide and once during inhalation of air plus oxygen. Before the study, participants' expectancies regarding the effects of nitrous oxide were assessed. Participants were blinded to drug administration. During each session, participants were verbally administered detailed measures of imagination and suggestibility: the Sheehan-Betts Quality of Mental Imagery scale and the Stanford Hypnotic Susceptibility Scale Form C, minus the hypnotic induction.


RESULTS
Imaginative suggestibility and imaginative ability (imagery vividness) were both elevated in the nitrous oxide condition. This effect was unrelated to participants' expectations regarding the effects of the drug.


CONCLUSIONS
Nitrous oxide increased imaginative suggestibility and imaginative ability. Possible explanations of these findings are discussed with respect to the effects of N-methyl-d-aspartate antagonists and to other pharmacological effects upon suggestibility and imagination.
Whalley
M G
MG
Hypnosis Unit, Department of Psychology, University College London, Gower Street, London, WC1E 6BT, UK. matwhalley@gmail.com
Brooks
G B
GB
D000280:Administration, Inhalation; D000328:Adult; D018685:Anesthetics, Inhalation / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D006990:Hypnosis; D007092:Imagination / Q000187:drug effects*; D008297:Male; D009609:Nitrous Oxide / Q000494:pharmacology*; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors; D016037:Single-Blind Method; D013404:Suggestion
D018685:Anesthetics, Inhalation; D016194:Receptors, N-Methyl-D-Aspartate; D009609:Nitrous Oxide