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Hypnosis is a state of heightened suggestibility in which people experience
imagined test suggestions as if they were real.
Franz Anton Mesmer (1734-1815)
• Mesmer developed a technique called ‘animal magnetism’ (later renamed mesmerism).
• Mesmer noticed that patients would often enter a trance-like state. Apparent ‘miracle cures’ also resulted.
• Eventually Mesmer realised the magnets were unnecessary .
Hypnosis
• In 1841 Scottish surgeon James Braid witnessed a demonstration of mesmerism and began to develop his own technique.
• Braid held a bright object in front of patients’ eyes while also making verbal suggestions.
• He argued mesmerism was a state of “nervous sleep” produced by concentrated attention.
• He renamed it hypnosis after Hypnos, the Greek god of sleep.
Hypnotic Induction Procedures
• Hypnotic induction is the process by which one person leads another into hypnosis.
• It is not necessary to swing a watch in front of the eyes or say “you are feeling sleepy”!
• Moss (1965) reported being able to sometimes induce a trance simply by saying “Please sit in that chair and go into hypnosis”!
• The goal of most induction procedures is to relax the subject and increase his or her attention.
• The only essential feature of any induction procedure is that the subject must realise that they are being hypnotised.
• In addition, it is not possible for someone to be hypnotised against their will.
• People differ in how susceptible they are to hypnotic suggestions. This can be measured by hypnotic susceptibility scales.
Sample test items from the Stanford Hypnotic Susceptibility Scale, Form C
Item Suggested Behaviour
Criterion for Passing
Arm lowering Right arm will become heavy
Arm lowered by at least 6 inches
Moving hands apart
Force is pushing hands apart
Hands are 6 or more inches apart
Mosquito hallucination
Mosquito is buzzing nearby
Any grimace or acknowledgement
Posthypnotic amnesia
Will not remember suggestions
Three or fewer items recalled
Hypnotic Susceptibility
• According to Hilgard (1977), in an average testing session 10% of subjects will be completely nonresponsive, 10% will pass all or nearly all items, and the rest will fall in between.
• Susceptibility can be enhanced by increasing people’s expectations (Spanos et al., 1991; Vickery & Kirsch, 1991).
Behaviour under Hypnosis• Hypnotised people are very suggestible and their
behaviour will conform with what the hypnotist tells them. Typical behaviour that can be induced include:
• Acting out imaginary scenes.• Pretending to be an animal.• Believing a limb cannot move or is insensitive to
pain.• Positive and negative hallucinations – seeing things
that are not really there, or not seeing objects that really are present.
• Posthypnotic suggestibility – a subject is given instructions under hypnosis and follows them after returning to a non-hypnotised state.
• Posthypnotic amnesia – the subject is instructed to not remember any of the suggested behaviour after leaving the hypnotic state.
Hypnosis and changes in perception
• Does hypnosis really change a person’s perception during positive and negative hallucinations?
• Miller et al. (1973) tested this hypothesis using the Ponzo illusion.
The Ponzo Illusion
• Miller et al’s study shows that under hypnosis the visual system was still processing sensory information.
• The effect of hypnosis is solely on conscious awareness.
Hypnosis and Involuntary Control
• When under hypnosis people subjectively experience their actions to be involuntary.
• Can people be made to perform acts that are harmful to themselves or others?
• Evans & Orne (1965) told hypnotized subjects that a cup of foaming liquid was ‘acid’.
• The subjects could be induced to dip their hands in the liquid and also throw it on someone’s face.
• However, a control group who were asked to simply pretend that they were hypnotised behaved in the same way.
• This behaviour can be explained in terms of “destructive obedience”; i.e., psychological compliance with an authority figure (Milgram, 1974).
• No evidence that hypnosis has a unique power to coerce people against their will.
Why does hypnosis work?
• There are two main competing explanations for how hypnosis works:
• Dissociation (state hypothesis) theories.
• Social Cognitive (non-state hypothesis) theories.
Dissociation theories of hypnosis
• Dissociation theories view hypnosis as an altered state of consciousness.
• Best known example is the neo-dissociation theory proposed by Ernst Hilgard (1978, 1991).
• Hilgard argued that cognition involves multiple systems of control which are not all conscious at the same time.
• These systems are controlled and motivated by a central ‘executive ego’.
Neo-dissociation Theory
• Hilgard argued that during hypnosis the hypnotist gains control of the executive ego, and therefore has access to the various subsidiary control systems.
• Hypnosis creates a division of awareness in which a person simultaneously experiences two streams of consciousness that are cut off from one another.
• One stream responds to the hypnotist’s suggestions, while the second stream remains a hidden observer of everything that occurs.
‘Hidden Observer’ Phenomenon
• In one study Hilgard (1977) hypnotised subjects and suggested that they would not feel pain.
• Then placed arm in ice-cold water for 45 seconds and reported level of pain experienced.
• For another group Hilgard said “Perhaps there is another part of you that is more aware than your hypnotised part. If so, would that part of you report the amount of pain”.
‘Hidden Observer’ Study (Hilgard, 1977)
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5 15 25 35 45
Normal PainHidden ObserverHypnotized Subject
• Hilgard argued that dissociation between streams of consciousness accounts for why hypnotism appears to produce involuntary actions.
• The subject intentionally carries out the actions, but only the ‘hidden observer’ is aware of this.
• The primary consciousness stream is cut off from this awareness and therefore the action appears involuntary to the subject.
Social Cognitive theories of hypnosis
• Social cognitive theories deny that hypnosis produces an altered state of consciousness.
• Instead argue that hypnotic experiences result from expectations of people motivated to take on the role of being “hypnotised”.
• Subjects develop a perceptual set – a readiness to respond to suggestions and to perceive hypnotic experiences as real and involuntary.
• In a study by Orne (1959) subjects were told prior to being hypnotised that a common feature of a trance is stiffening of the muscles in the dominant hand.
• This information was fictitious.• When the subjects were hypnotised, 55%
spontaneously displayed hand stiffening.• No subjects in a control group showed this
behaviour.• Social Cognitive theories do not claim that
hypnotised people are ‘pretending’. Expectations can influence behaviour without conscious awareness (e.g., placebo effects etc.)
Summary
• Hypnosis produces an increased receptiveness to suggestions.
• Hypnotised people subjectively experience their actions to be involuntary.
• Dissociation theories attribute this to divided streams of consciousness.
• Social Cognitive theories attribute this to subject’s expectation as to what effect hypnosis will have on them.
