1. Scientific Theories of Hypnosis
"any satisfactory theory of hypnosis should also be a theory bearing on psychology at
large" (Hilgard, 1991)
For over a century scientists and clinicians have proposed mechanisms to explain the
phenomenon associated with hypnosis. The key theories of hypnosis, historical and
current, are presented here. For the more recent models some knowledge of cognitive
psychology is useful. Within psychology most current models of how the mind works
what is termed 'executive function' make use of the concept of an executive control
system (Norman & Shallice, 1980, 1986) (a description of what is meant by executive
control is given on this page).
A key debate in hypnosis throughout the twentieth century has been between 'state'
vs. 'non-state' theories, properties of these types of theories are given below. Recently
attempts have been made to integrate findings from both of these positions.
Figure: Description of some properties of state and non-state theories of hypnosis
Theory Key Authors Description Type
Neodissociation
theory
Hilgard
Hypnotic phenomenon are produced
through a dissociation of high level
control systems.
State,
Dissociation
Integrated
dissociative theory
Woody &
Sadler
(1998)
A re-integration of dissociated experience
and dissociated control theories.
Dissociation

2. Socio-cognitive
theory
Spanos Non-state
Response
expectancy theory
/ Social cognitive
theory
Kirsch
(1985,
1991,
1994),
Lynn
An extension of social learning theory.
How a participant expectssuggestions to
change their subjective experience lead to
a change in experience, and can generate
involuntary responses.
Non-state
Role theory Sarbin Non-state
Integrative
cognitive theory
Brown,
Oakley
Integrative
Cold control
theory
Dienes,
Perner
Draws a distinction between:
being in a mental state
being aware of being in that state
Argues that successful response to
hypnotic suggestion can be achieved by
forming the intention to perform an
action, without forming higher order
thoughts about intending that action
Cognitive
Ego psychological
theory
Fromm
Conditioning and
inhibition theory
Barrios
Hilgard's Neodissociation Theory(Hilgard,1979,1986)
Hilgard's Neodissociation theory of hypnosis is a classic 'state' theory. It proposes that
hypnotic phenomenon are produced through a dissociation within high level control
systems. Essentially, the hypnotic induction is said to split the functioning of the
executive control system (ECS) into different streams. Part of the ECS functions
normally, but is unable to represent itself in conscious awareness due to the presence
of an 'amnesic barrier'. Hypnotic suggestions act on the dissociated part of the ECS
and the subject is aware of the results of the suggestions, but is not aware of the
process by which they came about.
"Effective suggestions from the hypnotist take much of the normal control away from the
subject. That is, the hypnotist may influence the executive function themselves and change
the hierarchical arrangements of the substructures. This is what takes place when, in the

3. hypnotic context, motor controls are altered, perception and memory are distorted, and
hallucinations may be perceived as external reality" (Hilgard, 1991)
Hilgard's theory was inspired by his experiments with the 'hidden observer'
phenomenon whereby a 'hidden part' of the mind of a subject experiencing hypnotic
pain relief could be encouraged to elicit reports of the 'true' pain experience. The idea
that the hidden observer demonstrates the presence of consicous and unconscious
executive systems in hypnosis is a controversial notion (e.g Heap et al, 2004; Kirsch &
Lynn, 1998).
Figure: Illustration of Hilgard's neodissociation theory of hypnosis (click to enlarge)
An illustration of Higard's hierarchical model of cognitive control is shown
above (Hilgard, 1973). Woody & Sadler (2008) note that Hilgards ideas of an 'amnesic
barrier' and the 'hidden observer' do not sit comfortably with cognitive or
physiological psychological models.
Gruzelier's Neurophysiological Theory(Crawford&Gruzelier,1992; Gruzelier,1998)
Neurophysiological theories of hypnosis propose that high hypnotisables have better
executive function than low hypnotisables and can thus deploy their attention in
different ways. Gruzelier (1998) presented a model of hypnosis characterised by changes
in brain function. The process of hypnosis is described in three stages, each with its
own characteristic pattern of brain activity. Gruzelier's neurophysiological account
emphasises that changes in the way the attentional control system operates in hynosis
renders the subject more suggestible.
In the first stage of the hypnotic induction the subject pays close attention on the words of
the hypnotist: activity is increased in predominantly left-sided fronto-limbic brain regions.
In the second stage the subject 'lets go' of controlled attention and gives control to the
hypnotist: there is a reduction in left frontal activity. The third stage sees an increase in
right-sided temporo-posterior systems as the subject engages in passive imagery. By

4. exhausting their frontal abilities during the induction the highs end up frontally impaired
in a hypnotic state (Dienes & Perner, 2007)
Gruzelier's model finds some support from behavioural and neurophysiological
evidence and complements other state-like accounts of hypnotic functioning.
However, interpretation of much of the evidence critical to such models is questioned
by sociocognitive theorists (e.g. Wagstaff, 2004). Crucially though, the predictions of
enhanced executive skills in high hypnotizables are testable.
DissociatedControl Theory(DCT) (Bowers,1992;Woody&Bowers,1994)
Dissociated control theory of hypnosis (DCT) applies the Norman and Shallice model of
executive control to explain hypnotic responding. The original version of the model
focussed on a functional dissociation between executive control and lower subsystems
of control. Woody & Bowers (1994) linked the theory to the Norman & Shallice mode.
The DCT model proposes that when highly hypnotizable individuals are hypnotized
the supervisory attentional system (SAS) has become functionally dissociated from
the contention scheduling system (CS) - that is, these two levels cease to work
together effectively. With the higher level control system partly disabled when high-
hypnotizables are hypnotized, the individual is more dependent upon lower-level CS-
based automatic processes. Contextual cues and suggestions from the hypnotist
influence the contention scheduling system and affect the hypnotized person's
experience directly.
A number of studies have been conducted to test hypotheses generated by DCT and
are reviewed in more detail in Jamieson & Woody (2007). One study used a difficult
version of the Stroop task (difficult so that it should require strong SAS involvement)
and found that highly susceptible individuals in hypnosis produced more errors than
low hypnotizables - a result predicted by DCT. However, some other studies have
found evidence for enhanced attentional control under hypnosis - contrary to what
DCT would predict. Jamieson & Woody (2007) conclude that current data do not support
a simple global shutdown of frontal functioning during hypnosis.

5. Figure: Woody & Sadler's integrative dissociative theory of hypnosis
Woody & Sadler (2008) presented an integrative model of dissociative theories of
hypnosis, shown above. and their chapter provides a comprehensive overview of this
topic. In their model, a theory of dissociated experience involves the weakening of path
c, and possibly of path e. A theory of dissociated control involves the weakening of path
b, and possibly of path a. A theory of second-order dissociated control involves the
weakening of path d.
Dissociated-ExperienceTheory
The dissociated experience theory of hypnosis argues that high hypnotisables execute
hypnotic responses voluntarily, but that this effort is not monitored correctly and is
dissociated from conscious awareness.
Coldcontrol theory(Dienes&Perner,2007)
Cold control theory of hypnosis considers the distinction between control and
awareness in terms of Rosenthal's 21 HOT (higher order thought) theory. According to
Rosenthal we are conscious of mental states by having thoughts about those states. A
thought about being in a mental state is a second-order thought (SOT), because it is a
mental state about a mental state (e.g. 'I see that the cat is black'). Third-order
thoughts (TOTs) are also possible, by becoming aware of having an SOT (e.g. 'I am
aware that the cat I am seeing is black'). The cold control theory of hypnosis states
that a successful response to hypnotic suggestions can be achieved by forming an
intention to perform the action or cognitive activity required, without forming the
HOTs about intending that action that would normally accompany reflective
performance of the action.
Read a full description of cold control theory on Zoltan Dienes' page
Social-cognitive / Cognitive-behavioural / Responsesettheory

6. Social-cognitive theories form the 'non-state' end of the 'state-nonstate debate'. State
theories argue that processes such as 'repression' or 'dissociation' operate when
subjects are given a suggestion, whereas non-state theories view subjects as active
"doers" and observe the suggested effect as an enactment rather than a
happening (Spanos et al, 1980).
Social-cognitive theory of hypnosis argues that the experience of effortlessness in
hypnosis results from participant's motivated tendencies to interpret hypnotic
suggestions as not requiring active planning and effort (i.e. the experience of
effortlessness stems from an attributional error). The attribution of volition depends
on the kind of response-set which has been put into place, and if a hypnotic response-
set is in place then volition is attributed externally. Put simply, effortlessness in
hypnosis comes about when individuals expect things to be effortless, and 'decide'
(more or less consciously) to respond along with suggestions.
One important factor to note when considering socio-cognitive hypnosis theories of
this sort is that they do not imply that subjects are always 'faking', or not really
experiencing an involuntary hypnotic response. Although these models use terms
such as 'role enactment' or 'self-presentation' they are still entirely consistent with the
notion that hypnotised participants have unusual experiences. (See an elaboration of
this point on the state/non-state page)
Spanos' Socio-Cognitive Theory
Also know variously as a 'cognitive-behavioural perspective' (Spanos & Chaves, 1989),
and a 'social-psychological interpretation' (Spanos, 1986). Spanos believed that
attitudes, beliefs, imaginings, attributions and expectancies all shaped hypnotic
phenomena.
"Spanos (1991) used the construct of strategic role enactment to explain how individuals
transform imaginings, thoughts, and feelings into experiences and behaviours that are
consistent with their ideas of how a good hypnotic subject should respond to the overall
hypnotic context and specific suggestions in particular. How subjects construe the
hypnotic role is thus a key determinant of hypnotic responsiveness."
He proposed that hypnotic behaviours could be explained by the same normal social-
psychological processes that explain non-hypnotic behaviours:
"The response of high hypnotisables to suggestions for amnesia, analgesia, and so on, are
often not what they seem, and ... such responses in fact reflect mundane social-cognitive
processes such as compliance-induced reporting biases, alterations in attentional focus,
and misattribution of experience, rather than such special processes as
dissociation" (Spanos & Coe, 1992).

7. Kirsch& Lynn's Social Cognitive Approach
This approach emphasises response expectancies as a determinant of
behaviour. Kirsch and Lynn (1997) propose that subjects in a hypnotic situation have
generalized response expectancy (a belief) that they will follow the hypnotists's
instructions and will produce behaviours that are experienced as involuntary. A
consequence of this is that these subjects attribute hypnotic responses to external
causes (i.e. the hypnotist) and experience them as involuntary. According to this
theory hypnotic responses are initiated by the same mechanisms as voluntary
responses, the difference is in how the behaviours are experienced.
Sarbin's Role Theory(Sarbin, 1950; Sarbin, 1954; Sarbin &Coe, 1973; Coe &Sarbin,
1992)
A general theoretical framework for understanding human social behaviour.
Sarbin (1954); Sarbin (1950; Sarbin & Andersen (1967); Sarbin & Coe (1973); Coe &
Sarbin (1991)
Kihlstrom's ThirdWay(Kihlstrom,2008)
"...it is clear what we should do, which is abandon the stance of either-or and adopt a
new stance of both-and. This 'third way' in hypnosis research construes hypnosis
simultaneously as both a state of (sometimes) profound cognitive change, involving basic
mechanisms of cognition and consciousness, and as a social interaction, in which
hypnotist and subject come together for a specific purpose within a wider socio-cultural
context." (Kihlstrom, 2008)
Brown&Oakley's Integrative Cognitive Theory(Brown&Oakley,2004; Brown,
1999; Oakley,1999)
Placing emphasis on the nature of perception and consciousness, Brown & Oakley
(2004) incorporate ideas from both dissociated control and response set theories. They
include the dissociated control theory concept that suggested responses may be
facilitated by an inhibition of high-level attention, and the response-set idea that
suggested involuntariness is an attribution about the causes of behaviour.

8. Figure: Brown & Oakley's (2004) integrative cognitive model of hypnosis
Ego-Psychological Theory(Fromm,1979)
Ego-psychological theory of hypnosis is based on Shor's idea that the depth of a
hypnotic trance is related to the degree to which the participant loses awareness of the
distinction between imagination and reality. This distinction is termed the
'generalized reality orientation' and is characteristic of normal psychological
functioning. Ego-psychological theory distinguishes between primary processes
(emotional, holistic, illogical, unconscious, developmentally immature) and secondary
processes (affect-free, analytical, logical, conscious, developmentally mature).
Whereas normal adult functioning is biased towards secondary processing the
induction of hypnosis makes the subject 'let go' of some secondary process activity.
Heap et al (2004) characterise the evidence for ego-psychological theory as mixed.

9. Critically, this theory is not a well-specified as some other more cognitive theories,
and is thus not as easily testable or falsifiable.
Conditioningandinhibition theory(Barrios,2001)
In this theory a hypnotic induction is defined as the giving of a set of suggestions so
that a positive response to a previous suggestion conditions the subject to respond
more strongly to the next suggestion. This induction is placed in a conditioning
paradigm. A hypnotic induction is explained as the conditioning of an inhibitory set,
which increases responsivity to suggestion by inhibiting stimuli and thoughts which
would contradict the suggested response.