Posts tagged ‘hypnosis’

Maybe hypnosis is the right state of mind and ‘normal’ is really ‘under-hypnotised’?

That’s one idea that does not appear in the comprehensive synthesis of what we know about hypnosis produced by Terhune, Cleeremans, Raz and Lynn. It is a dense, concentrated document, thick with findings and sources, but they have done a remarkably good job of keeping it as readable as possible, and it’s both a useful overview and full of interesting detail. Terhune has picked out some headlines here.

Hypnosis, it seems, has two components; the induction and one or more suggestions. The induction is what we normally think of as the process of hypnotising someone. It’s the bit that in popular culture is achieved by a swinging watch, mystic hand gestures or other theatrical stuff; in common practice probably just a verbal routine. It seems that although further research is needed around optimising the induction, the details are much less important than we might have been led to think, and Terhune et al don’t find it of primary interest. The truth is that hypnosis is more about the suggestibility of the subject than about the effectiveness of the induction. In fact if you want to streamline your view, you could see the induction as simply the first suggestion. Post-hypnotic suggestions, which take effect after the formal hypnosis session has concluded, may be somewhat different and may use different mechanisms from those that serve immediate suggestions, though it seems this has yet to be fully explored.

Broadly, people fall into three groups. 10 to 15 per cent of people are very suggestible, responding strongly to the full range of suggestions; about the same proportion are weakly suggestible and respond to hypnosis poorly or not at all; the rest of us are somewhere in the middle. Suggestibility is a fairly fixed characteristic which does not change over time and seems to be heritable; but so far as we know it does not correlate strongly with many other cognitive qualities or personality traits (nor with dissociative conditions such as Dissociative Identity Disorder, formerly known as Multiple Personality Disorder). It does interestingly resemble the kind of suggestibility seen in the placebo effect – there’s good evidence of hypnosis itself being therapeutically useful for certain conditions – and both may be correlated with empathy.

Terhune et al regard the debate about whether hypnosis is an altered state of consciousness as an unproductive one; but there are certainly some points of interest here when it comes to consciousness. A key feature of hypnosis is the loss of the sense of agency; hypnotised subjects think of their arm moving, not of having moved their arm. Credible current theories attribute this to the suppression of second-order mental states, or of metacognition; amusingly, this ‘cold control theory’ seems to lend some support to the HOT (higher order theory) view of consciousness (alright, please yourselves). Typically in the literature it seems this is discussed as a derangement of the proper sense of agency, but of course elsewhere people have concluded that our sense of agency is a delusion anyway. So perhaps, to repeat my opening suggestion, it’s the hypnotised subjects who have it right, and if we want to understand our own minds properly we should all enter a hypnotic state. Or perhaps that’s too much like noticing that blind people don’t suffer from optical illusions?

There’s a useful distinction here between voluntary control and top-down control. One interesting thing about hypnosis is that it demonstrates the power of top-down control, where beliefs, suggestions, and other high-level states determine basic physiological responses, something we may be inclined to under-rate. But hypnosis also highlights strongly that top-down control does not imply agency; perhaps we sometimes mistake the former for the latter? At any rate it seems to me that some of this research ought to be highly relevant to the analysis of agency, and suggests some potentially interesting avenues.

Another area of interest is surely the ability of hypnosis to affect attention and perception. It had been shown that changes in colour perception induced by hypnosis are registered in the brain differently from mere imagined changes. If we tell someone under hypnosis to see red for green and green for red, does that change the qualia of the experience or not? Do they really see green instead of red, or merely believe that’s what is happening? If anything the facts of hypnosis seem to compound the philosophical problems rather than helping to solve them; nevertheless it does seem to me that quite a lot of the results so handily summarised here should have a bigger impact on current philosophical discussion than they have had to date.