I remember when as a young fellow in New Ross, the hypnotist Paul Golden would book St Michael's Hall for a week each year. He would ask us to put our hands together with fingers intertwined and announce that when he told us to unclasp our hands some of us would be unable to do so. Those unable to unclasp their hands were asked onto the stage to be hypnotised and to do foolish things for the great amusement of the audience.
Hypnosis is now under serious scientific analysis and it has been shown to have useful medical and psychological applications in controlling chronic pain, countering anxiety and helping people to recover faster from out-patient surgery.
Hypnosis is a special state induced in a subject by a hypnotist who typically asks the subject to stare at a small stationary object, such as a coloured spot on the wall. The hypnotist makes soothing suggestions to the subject to relax and concentrate.Some people describe their experience under hypnosis as an altered state of consciousness, others describe it as a state of focused attention. Most people enjoy the experience.
Under hypnosis, the subject actively responds to suggestions made by the hypnotist. Some people are very responsive to suggestions; he extent of the response is termed the "hypnotisability" of the subject and most people can be hypnotised to some degree.
People under hypnosis don't lose control over their behaviour and are not swayed by suggestions to take actions that conflict with their normal moral standards. They usually remain aware of who and where they are and, unless amnesia has been specifically suggested, they usually remember what happened during hypnosis.
Depth of hypnosis is measured by the Stanford Hypnotic Susceptibility Scales. In one activity, hypnotised subjects are told they have no sense of smell, then a bottle of ammonia is waved under their nose. If they show no reaction they are deemed very responsive. Stanford Scales scores can range from zero (no response to any hypnotic suggestion) to 12 (subject responds to all suggestions). Ninety five per cent of people receive a score of at least one and most people score about six.
Individual hypnotisability is stable over the course of adulthood. It is relatively unaffected by the characteristics of the hypnotist (age, gender, experience and so on). Hypnotisability is related to the subject's capacity to become absorbed in activities such as reading, enjoying music or daydreaming. However, it is unrelated to personality traits such as trust, gullibility, hysteria, aggressiveness, submissiveness, social compliance or imagination.
Subjects under hypnosis are very responsive to suggestions, but they are not automatons. They follow their normal cultural and moral standards. However, the subject typically experiences hypnotically suggested behaviour to be effortless i.e. not something that is actively achieved.
Following on suggestion, subjects move without conscious intent, do not feel painful stimulation and so on. Hypnotists can also create hallucinations, false memories, compulsions and delusions in subjects under hypnosis.
One persistent objection to the validity of hypnosis is the idea that the phenomenon is just a matter of having a particularly vivid imagination. This is not true - many imaginative people are poor hypnotic subjects.Studies have also shown that different regions of the brain are activated when subjects are asked to imagine a sound than when they are having a hallucinatory experience of the sound under hypnosis.
One controversial claim is that hypnosis can be used to recover memory, even memory of early childhood. This is almost certainly untrue. Cognitive scientists tell us that we normally distinguish between genuine memories and imagined ones by noting the amount of effort expended in originally encoding the memory.
All our memories have such effort tags attached. If the tag notes a high effort we interpret the memory as imagined; if the tag notes little mental effort, we interpret the memory as real. Since feelings of effortlessness are characteristic of the hypnotic state, hypnotised subjects can easily confuse an imagined past event with something that actually happened.
Highly hypnotisable subjects are easily led to "remember" detailed accounts of their first months of life despite the fact that adults have no capacity to remember early infancy.
Hypnosis has been professionally validated as an effective intervention to relieve pain in various circumstances, ranging from cancer to the pain of women in labour. Hypnosis is also helpful when used together with conventional cognitive behaviour therapy in the treatment of obesity, insomnia, anxiety and high blood pressure. Unfortunately, hypnosis does not appear to be very effective in the treatment of alcoholism or other drug addictions, including addiction to cigarettes.
There was a good overview of hypnosis in Scientific American in July 2001. For more details on this subject, consult Hypnosis for the Seriously Curious, by Kenneth Bowers (WW Norton, New York, 1993).
Finally, I trust you found this article sufficiently hypnotic to act on my suggestion that you buy my book, Understanding the Natural World - Science Today available from The Irish Times, General Services Section, or itbooks@irish-times.ie
• William Reville is associate professor of Biochemistry and director of Microscopy at UCC