Is Hypnotic Induction Necessary to Experience Hypnosis and Responsible for Changes in Brain Activity?
Alejandro Luis Callara, Žan Zelič, Lorenzo Fontanelli, Alberto Greco, Enrica L. Santarcangelo, Laura Sebastiani
Brain Sciences May 29, 2023 DOI: 10.3390/brainsci13060875 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Observational study Peer reviewed |
|---|---|
| Sample size | 31 |
| Population | Adults with high or low hypnotizability scores according to the Stanford Hypnotic Susceptibility Scale, form A |
| Measures | Stanford Hypnotic Susceptibility Scale, form A; power spectral density (PSD) of theta, alpha, and gamma; Determinism (DET) and Entropy (ENT) of the EEG Multidimensional Recurrence Plot (mRP) |
| Citations | 7 |
| Key findings | High-hypnotizability participants reported greater changes in consciousness than lows, but theta, alpha, and gamma power spectral density showed no condition-related changes in either group. Alpha power was larger in highs on midline sites, and theta and gamma power differed by region between groups across conditions. Determinism of the EEG signal positively correlated with hypnotizability during hypnosis, while entropy showed no correlation. The authors suggest formal hypnotic induction may be of limited relevance for highs who know their hypnotizability and expect hypnosis. |
Abstract
The relevance of formal hypnotic induction to the experience of trance and its neural correlates is not clear, in that hypnotizability, beliefs and expectation of hypnosis may play a major role. The aim of the study was assessing the EEG brain activity of participants with high (highs) or low hypnotizability scores (lows), aware of their hypnotizability level and informed that the session will include simple relaxation, formal hypnotic induction and neutral hypnosis. A total of 16 highs and 15 lows (according to the Stanford Hypnotic Susceptibility Scale, form A) were enrolled. Their EEGs were recorded during consecutive conditions of open/closed-eyes relaxation, hypnotic induction, neutral hypnosis and post hypnosis not interrupted by interviews. The studied variables were theta, alpha and gamma power spectral density (PSD), and the Determinism (DET) and Entropy (ENT) of the EEG signal Multidimensional Recurrence Plot (mRP). Highs reported significantly greater changes in their state of consciousness than lows across the session. The theta, alpha and gamma PSD did not exhibit condition-related changes in both groups. The Alpha PSD was larger in highs than in lows on midline sites, and the different sides/regions' theta and gamma PSD were observed in the two groups independently from conditions. ENT showed no correlation with hypnotizability, while DET positively correlated with hypnotizability during hypnosis. In conclusion, the relevance of formal hypnotic induction to the experience of trance may be scarce in highs, as they are aware of their hypnotizability scores and expecting hypnosis. Cognitive processing varies throughout the session depending on the hypnotizability level.