Look Into My Wide, Vacant, Eyes

When I was in my first year at college I went to a hypnotism “show”, or “exhibition”, or “demonstration”… I don’t know … anyway, a hypnotist came and hypnotized people. Being naturally curious, I volunteered. Also, either because of my natural skepticism or through the incompetence of the hypnotist I failed to become entranced. But a friend of mine was. She was told to imagine the boy next to her naked, and immediately burst out laughing. When the hypnotist asked her why she was so amused, she gave a telltale gesture with her pinky finger.

So what is going on in a hypnotized brain? Hypnosis research has been embroiled in a debate for years: Is there a hypnotic “state” that is different from all other emotional states, or is it a phenomenon that depends on states observed in the non-hypnotized population?

A paper published by Sakari Kallio and colleagues in PLoS ONE this month appears to have found evidence for a specific hypnotic, a.k.a. trance, state. Building on previous fMRI and PET studies, the authors conducted a case study on subject TS-H, who is known to be highly susceptible to suggestion.

Yes, there is a scale measuring hypnotic susceptibility. Andre Muller Weitzenhoffer, a prominent psychologist whose prolific career focused on the ins and outs of hypnosis, developed this Stanford Scale in the late 1950s. And here it is:

0 – Eye Closure (not scored)
1 – Hand Lowering (right hand)
2 – Moving Hands Apart
3 – Mosquito Hallucination
4 – Taste Hallucination
5 – Arm Rigidity (right arm)
6 – Dream
7 – Age Regression (school)
8 – Arm Immobilization
9 – Anosmiia to Ammonia
10 – Hallucinated Voice
11 – Negative Visual Hallucination
12 – Post-Hypnotic Amnesia

TS-H scored a 12, and thus has been called upon many times to play the part of experimental subject in a variety of hypnosis experiments.

In the current paper TS-H and a cohort of control subjects were hypnotized by a professional hypnotist (although sadly I couldn’t find out the exact details of how this was achieved). The authors then looked at the physiology of the eye while the participants were in the hypnotic state. They assessed a variety of functions, including frequency of blinking, the size of the pupils, and several measurements of their ability to focus. In all of these cases TS-H showed dramatic differences in and out of the hypnotic state; she blinked far less, her pupils constricted, and her eyes did not move as much in response to external stimuli. She was also far more likely to exhibit these effects than the control participants.

Importantly these experiments provide conclusive evidence for a distinct hypnotic state (immediate induction and cancellation, objective confirmation through measurements, and showed features that are impossible to imitate). While the authors admit that “It is also possible that TS-H has somehow acquired a special ability to control her eye behavior and was in fact just using this ability during the experiment”, the fact that the behaviors she exhibited are generally very difficult to control voluntarily suggests this is unlikely.

This paper will also allow for less invasive monitoring of the hypnotic state, although I doubt we will ever see a hypnotist measuring the pupil size of their unwitting volunteers.


Katie Pratt is a graduate student in Molecular Biology at Brown University. She has a passion for science communication, and in an attempt to bring hardcore biology and medicine to everyone, she blogs jargon-free at www.katiephd.com. Follow her escapades in the lab and online on Twitter.



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5 comments so far. Join The Discussion

  1. Adny

    wrote on October 26, 2011 at 2:32 pm

    Andre Muller Weitzenhoffer!

  2. [email protected]

    wrote on October 26, 2011 at 2:41 pm

    We've got ourselves a winner!

  3. @JacquelynGill

    wrote on October 26, 2011 at 2:33 pm

    André Muller Weitzenhoffer!

  4. Nick Othen

    wrote on February 21, 2013 at 5:58 am

    Interesting article but the field of hypnosis has moved forward since the 1950's.

  5. @richardjdsouza

    wrote on October 28, 2013 at 6:29 pm

    There is a small percentage of the population that is more suggestible than the rest. They have incredible visualisation abilities. They tend to be shortlisted in a typical stage hypnosis show. As part of a hypnotherapy course, they respond very well to treatment. The rest of the population can be receptive; it just takes the right mix of "want", skill of hypnotherapist, empathy between hypnotherapist and patient etc.

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