A recent paper (citation below) has investigated a particular person who is very easy to hypnotize. The authors make an argument for single case studies at the beginning of an investigation. I found this interesting because I usually feel disappointment in single case studies. This defense seemed to make sense.
We propose that the research field of hypnosis should also include an approach that has proven to be very effective in cognitive neuropsychology; namely using detailed case studies as one line of research to make initial theoretical progress in a relatively new and fuzzy area of empirical research. This approach has previously shed new light on many rare phenomena e.g. Capgras syndrome or synaesthesia. Furthermore, such studies have consequently led to better general understanding of brain functioning. However, since we only presented the results of a single case, we cannot draw conclusions about hypnosis in general or even about other hypnotic virtuosos.
Two things held them to this study: a particular stare is associated with traces/hypnosis for many observers and some regions of the brain (anterior cingulate cortices and dorsolateral prefrontal cortex) are associated with hypnosis and with control of the eyes. They compared the subject TS-H with a matched group in a normal conscious state, and in a hypnotic one for TS-H and attempting to fake hypnotic stares for the others. The fakers were not without help: they were shown movies to TS-H’s stare and instruction on the various differences between the stare and normal eye movements.
We showed that a Hypnotically Induced Stare (HIS) is accompanied by large, objective and inimitable changes in the patterns of eye movements in the case TS-H. The amplitude, velocity and frequency of reflexive saccades were radically suppressed, and the fixation time was increased. Also the pupil size of TS-H diminished during the hypnosis condition.
These effects are difficult or impossible to fake and the control group could not – not too surprising as they are automatic actions.
We suggest that the hypnotic state does not occur in all who are classified as highly-hypnotizable by using current hypnotisability scales, but only in a small subgroup of them. The external manifestation of those who enter the hypnotic state may be the classical Hypnotically Induced Stare (HIS). However, this result does not rule out the possibility of a hypnotic state being present without accompanying change in eye behaviour.
But at least some people can be hypnotized – it is a distinct state of consciousness – it can be objectively observed. Even if suggestibility is a spectrum from people like TS-H and those that completely resist suggestions, it is still clear that the extreme end can be identified and probably cannot be faked. Or if it is rare, it is possible to tell the difference between it and people who are fooling themselves or others. A step forward on the basis of a single case study is causing me to change my prejudice against them.
Kallio, S., Hyönä, J., Revonsuo, A., Sikka, P., & Nummenmaa, L. (2011). The Existence of a Hypnotic State Revealed by Eye Movements PLoS ONE, 6 (10) DOI: 10.1371/journal.pone.0026374