Throughout the 19th and 20th centuries a number of theories of hypnosis have been proposed.

There are currently two modern theoretical arguments of hypnosis being proposed.

• One attempts to explain hypnosis by integrating modern brain activity studies and current understanding of what happens in the brain during hypnosis induced states; believing hypnosis to be a 'special state'.

• The other attempts to explain hypnosis by applying current practices of cognitive behavioural psychology to ordinarily accepted states. These researchers propose a cognitive behavioural theory based on socio-cognitive concepts to explain hypnosis.

Neither of these actually support any new innovative thinking in theoretical development. So the debate is whether hypnotic trance is a special state or not; and so, you have state and non-state theoretical debates taking place.

• State theorists argue that the effects of hypnosis are explained as a special neuro-psychological state.

Hilgard’s neo-dissociation theory views hypnotic trance as an artificially-induced state of psychological dissociation.

• Non-state theorists argue that hypnosis is the application of a number of ordinary psychological states, like focused concentration, expectation, and imagination. They explain hypnosis by comparing it to mainstream psychological concepts. Hence, why some psychologists support the cognitive behavioural theory of hypnosis.

Current Theories of Hypnosis

• The so called modern dissociation theory of hypnosis suggests that hypnosis is a dissociative state (Kirsch and Lynn 1998) created by neuro-physiological factors (Gruzelier 2006).

• Dissociation can be defined as the splitting of awareness or the separation of the conscious and unconscious thought processes.

• Neo-dissociation theory (Hilgard 1986) states that hypnosis is the result of dividing consciousness into two or more simultaneous components of awareness.

• Dissociated control theory (Bowers 1992) states that hypnotic processes weaken or dissociate frontal control of behavioural schema thus allowing direct activation of suppressed behaviours.

• Brain functionality is required in order to affect dissociation (hypnosis) as an altered state.

• It is suggested that physiologically the thalamo-cortical attentional network engages a left fronto-limbic focused attention control system that underpins sensory fixation and concentration, whilst stimulation of fronto-limbic inhibitory systems through suggestions triggers a sense of tiredness and relaxation.

• Right sided temporal posterior functions are engaged through suggestions for imagery and dreaming. It is suggested that this is what facilitates the splitting of conscious awareness, and that is what hypnosis is (Gruzelier 1998, 2006).

• This theory is supported by brain imaging studies during hypnosis.

Positron emission tomography (PET), functional magnetic resonance imaging (fMRI) and computerised tomography (CT or CAT) studies are now facilitating a greater understanding of the functioning of the brain during hypnosis.

Studies show that during hypnosis functionality of brain areas such as the rostral anterior cingulate cortex, posterior cerebellum, the ventro-medial pre-frontal cortex, mid-cingulate cortex and hippocampus all significantly differ from what is observed in the alert non-hypnotic state (Feymonville et al 2000, Schulz-Stübner et al 2004).

There is also a modern field of medicine called psychoneuroimmunology which is based on the mind/body connection. This field of study has been growing significantly in the past 25 years. The research coming from this field of study is producing an ever-growing body of evidence that supports a link between mind, body and spirit. This also demonstrates that hypnosis facilitates working within these connection processes. This has also allowed the development and understanding of the link between psychological process and immune system response and function. This is now being recognised by the medical community as the basis of working with a variety of medical conditions where immune disregulation is present: for example cardiovascular disease, osteoporosis, arthritis, Type 2 diabetes and cancers (Kiecolt-Glaser et al 2002). It is now recognised that the influencing of emotional factors through hypnosis has both a direct and indirect action on improving immune system functioning and consequently the health of a patient and the course of a disease (Lutgendorf and Costanzo 2003).

• Modern medicine is beginning to recognise that the teaching of an understanding of hypnosis and other integrative medicines in medical schools will allow doctors to make informed decisions with regard to referrals for treatment (Kligler et al 2004).

• A term being used nowadays is 'mindfulness'; it appears that some practitioners are trying to distance themselves from the term 'hypnosis', as hypnosis has some negative connotations associated with it.

Historical Theories of Hypnosis:

• Modified sleep theory (1899) - James Braid suggested that if a subject fixes their attention on a single thing, this would result in a state of ‘nervous sleep’. He believed that in this state, people are highly suggestible and that they awake with no memory of what happened.

• Psychoanalytical theory (1909) - Sándor Ferenczi, a colleague of Sigmund Freud, hypothesised that the patient-therapist relationship is very similar to the child-adult relationship (Waxman 1989). He said that a patient would go into trance to please their therapist: having assumed the role of a child, the patient will relate to the therapist with the obedience of a child to its parent.

• Conditioned response theory (1957) - Ivan Pavlov (1927), proposed this theory based on the concept of conditioned response. Pavlov hypothesised that the subject is conditioned to respond to the word ‘sleep’ (Waxman 1989). As the therapist talks about sleep, the patient responds with behaviour associated with falling asleep and begins to feel tired, heavy-limbed and drowsy.

• Dissociation theory (1925) - Pierre Janet (1925) put forward the theory that hypnosis and hysteria are closely associated. As hysteria causes the mind to split into two parts (or dissociate), Janet hypothesised that hypnosis produces a similar effect, causing the conscious to split from the unconscious, with the unconscious becoming dominant. Janet believed that amnesia was a side-effect of this process.

• Physical theory (1957) - This is a theory with several proponents (Waxman 1989), the earliest being Barry Wyke (1957, 1960). It states that closing down some sensory functions, particularly alertness and attention governed by the reticular activating system found in the central part of the brain stem, makes the patient more susceptible to suggestion. With eyes closed, the patient focuses on aural stimuli, including the therapist’s voice, which directs the subject through a process of relaxation that diminishes their awareness of their environment and reduces the activity of the reticular activating system. This leads to physical disorientation, which produces the altered state of consciousness of hypnosis.

• Suggestion theory (1886) - Hippolyte Bernheim (1900) believed that hypnosis was simply a state of mind that was induced in one person by another – not such an obvious idea at the time as it appears now. He said that everything that happens in hypnosis is caused by the therapist’s power of suggestion over the patient. Unfortunately, this theory does not take into account hypnotic states and phenomena induced by inanimate objects such as mirrors and pendulums.

• Role-playing theory (1941) - R.W. White (1941) explained hypnosis as a result of the subject’s striving towards a goal. White said that during a hypnosis session the most general goal for the subject is to behave like a hypnotised person – whatever the therapist and the subject believe that to consist of. The subject plays the role of a person in a hypnotic trance.

• Atavistic regression theory (1960) - Ainslie Meares (1960) said that trance inhibits the higher centres of the brain, and the subject reverts to an atavistic (primitive) state of functioning in which the parts of the brain that evolved first dominate. The subject, operating without logic or rationality, accepts the hypnotist’s suggestions.

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