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Clinical assessment of hypnotisability

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Abstract

Hypnosis is an important therapeutic modality which, when used alone or in conjunction with cognitive-behavioural or pharmacological treatments, has high rates of success across a diverse range of psychological and medical areas (eg., Moore & Burrows, 1991; Moore, 1992). However, just as people vary across a range of physical, emotional, and intellectual domains so too do they vary on their level of hypnotisability. We might then ask is it either good or ethical practice to use hypnosis with people who have little or no hypnotic ability. Typically, the operationalisation of a construct is based upon definitional terms which, in turn, derive from a conceptualisation of the relevant phenomena. With regard to hypnosis, these conceptualisations and definitions are diverse however the operationalisation of assessment is, somewhat surprisingly, rather homogeneous across a limited range of phenomena. This paper will stress the importance of context and ethical practice in the role of clinical assessment, and it will provide an overview of some of the major tests of hypnotisability, its known correlates, and relevant psychometric principles.
Clinical applications of hypnotic assessment Moore & Powlett
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Moore, K.A., & Powlett, V. (1998). Clinical assessment of hypnotisability. In B.J. Evans &
G.D.Burrows (Eds.). Hypnosis in Australia (pp.337-377). Melbourne: Australian Hypnosis
Society.
Clinical assessment of hypnotisability
Kathleen A Moore
Deakin University
Burwood 3125 Australia
email: kmoore@deakin.edu.au
and
Vicky Powlett
Psychologist in Private Practice
Toorak 3142, Australia
email v.powlett@medicine.unimelb.edu.au
Keywords: assessment, hypnotisability, reliability, validity, ethics, clinician
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If the practice of hypnosis and hypnotherapy is to be based on
scientific findings ... Appropriate investigations in the context of the
clinic should be conducted, following the same rules of evidence
which apply to the laboratory investigations (Hilgard, 1982, p. 394-
5).
Hypnosis is an important therapeutic modality which, when used alone or in conjunction with
cognitive-behavioural or pharmacological treatments, has high rates of success across a diverse
range of psychological and medical areas (eg., Moore & Burrows, 1991; Moore, 1992).
However, just as people vary across a range of physical, emotional, and intellectual domains so
too do they vary on their level of hypnotisability. We might then ask is it either good or ethical
practice to use hypnosis with people who have little or no hypnotic ability. Typically, the
operationalisation of a construct is based upon definitional terms which, in turn, derive from a
conceptualisation of the relevant phenomena. With regard to hypnosis, these conceptualisations
and definitions are diverse however the operationalisation of assessment is, somewhat
surprisingly, rather homogeneous across a limited range of phenomena. This paper will stress the
importance of context and ethical practice in the role of clinical assessment, and it will provide
an overview of some of the major tests of hypnotisability, its known correlates, and relevant
psychometric principles.
Why is assessment important?
Testing is used for both diagnostic and decision-making purposes the latter relating to issues
such as suitability for entry to a profession, to certain training programs, or to treatment. In
general terms, standardised assessment techniques used in conjunction with other assessment
devices such as interviews and previous history, allow for the screening and selection of
participants, pre- and post-treatment comparisons, intergroup comparisons, and prediction. It is
important, therefore, that such tests have appropriate psychometric properties.
The properties of a ‘good’ test
The operationalisation (ability to measure) of any phenomenon is based upon a valid definition
of the construct and a reliable and valid measurement device. The most widely used devices in
assessing hypnotisability are the observer (or clinician) rated scales although there are some self-
report instruments. Despite the nature of reporting, each instrument must demonstrate reliability
and validity and it is important to understand what is meant by these terms.
Clinical applications of hypnotic assessment Moore & Powlett
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Reliability
Reliability refers to the consistency of the test: internal reliability (eg, Cronbach alpha, Kuder-
Richardson 19 or Kuder Richardson 20, split-half reliability) is the consistency of the test across
all items, that is, each question is assessing the same construct; test-retest reliability (usually
based upon Pearson Product Moment Correlations) is where the subject’s performance or score
on the same test is consistent when measured at different points across time. In order to
overcome learning or practice effects, test-retest reliability is often better assessed using
alternate forms of the same test. Obviously, these alternate forms would need to assess the same
construct and be equivalent in all aspects, eg, length, style of presentation, level of difficulty,
method of scoring. In order to assess ‘how reliable is the test statistic’, it is important to
understand the range of a correlation or alpha, the concepts of measurement error (often termed
residual) and amount of variance explained1.
Measurement error (residual) refers to the amount of inaccuracy attributable to the measuring
device at any one time and leads into the concept of real limits. For example, suppose we were to
measure your weight in kilograms: your bathroom scales record your weight at 72 kilos but you
know (hope) they weigh heavy by about 2 kilos, so this reduces you to 70 kg (the 2kgs is a
measurement error); our bathroom scales weigh you in at 69.9kg and (lucky for you) we think
they are reasonably accurate; the scales at our clinic show you as 70.1kg (sorry!) which again,
we believe are accurate. So, how much do you weigh?
Whilst we would probably record you as weighing 70kg., in reality we can never know exactly
what you weigh as all scales have some variation, but we could say that the real limits (allowing
for a reasonable amount of variation) of your weight are between 69.5 and 70.5kgs. You have
probably noticed that measurement error can be either plus or minus. All measurements,
particularly those subject to human judgement (and subject performance) such as involved in the
assessment of hypnotisability contain measurement error - the trick is, to keep this as low of
possible. How will you know this? Well, you probably won’t, so the next best thing is to make
the test (the scales) as accurate as you can (in this case the task of writer of the test but as you
should review these issues before deciding upon a test, it is also up to the user to disregard any
test with poor psychometric properties).
1 For a fuller account of these principles see any major text on testing eg., Anastasi, 1993; Murphy & Davidshoefer,
1994.
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The correlation statistic ( r ) has a range of ± 1, where 0 indicates no relationship or co-variation
between the measures or items and 1 indicates a perfect relationship. A positive sign merely
indicates that both measures covary in the same direction (eg, high scores on both arithmetic and
on spelling) while a negative sign indicates covariation in opposite directions (eg, fast on an
arithmetic test and high on accuracy).
If a test is stable over time, the two measures will be positively correlated. Because there will
also be some level of measurement error (a generally unknown amount) the correlation between
testing at Time 1 and Time 2 will not be 1, but in order to say that the test is temporally reliable
this coefficient needs to be close to 1. Numerous authors have debated ‘what is close to 1’ and
the consensus seems to be .70 (Anastasi, 1982). But what does a correlation of .70 mean? Here
we come to the concept of shared variance and another statistic the coefficient of determination,
which is simply the correlation value squared.
In the example above, if r=.70 then r2 = 49%: this means that nearly half the variance in one
score is explained by the variance in the other (and vice versa with only 2 scores). While at first
glance this may seem satisfactory, one needs to ask: What about the other 51% of unexplained
variance? Naturally, some of that will be measurement error: the instruments were not exactly
the same, people were more tired this time than last, it was too hot on Time 1, etc., but there is
also a component of ‘unreliability’, that is, the same construct is not being assessed at both times.
It is up to the user to decide how much of this is tolerable and this will, of course, be governed
largely by the availability of better testing alternatives and by the purpose for which testing is
undertaken. For instance, in some circumstances, either clinical or research-based, there is little
tolerance for error and low reliability, while in other perhaps less threatening situations, more
variation can be accepted. Of course, the higher the correlation the more reliable or stable the
instrument over time where the recommended interval between testing generally should not
exceed six months (Anastasi, 1982).
Internal Consistency
Evaluation of the homogeneity of test items is obtained through a measure of internal
consistency. The most commonly reported of these statistics is Cronbach’s alpha (α) which is
typically best applied when participants answer the test question using a Likert format (eg., 0
Clinical applications of hypnotic assessment Moore & Powlett
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‘Never’ to 5 ‘Always’), although the Kuder-Richardson formula is more applicable to items rated
as right or wrong or some other all or none scoring system. Despite these differences, the
interpretation of the statistic is essentially the same: the higher the figure (again generally
accepted as .7) the more homogeneous the items assessed. Of course, the tests items may by
their very nature be heterogeneous. For example, while tests of hypnotisability typically yield
one score (hence one reliability score) it must be queried whether the hypnotic abilities typically
tested such as age regression, cognitive distortion or hallucination, selective amnesia, or body
movement or rigidity are in fact homogeneous. These and other phenomenon exhibited during
hypnosis may form ‘clusters’ of abilities which need to be considered within such a framework,
thus potentially increasing reliability for each cluster (or factor) while reducing it if assessed
globally.
Validity
Validity simply refers to how valid or truthful this test is in assessing the construct under
investigation. It is possible for a test to be reliable (consistent across items and/or across time)
but not valid. For example, people can be tested on their ability to spell words but even if they
score high on spelling this is not an indicator of reading comprehension even though it is
probably likely that performance on the two abilities would be correlated.
Numerous types of validity prevail: content validity, an examination of the test content to
ascertain if it covers a representative sample of the abilities or behaviours to be assessed and
although this may appear similar to face validity this last is concerned not with what the test
measures but with what it appears to measure especially to those taking the test. Criterion-
validity refers to whether test scores are actually able to predict the ability they are said to test;
while construct validity relates to the degree to which the test actually measures what it purports
to measure, that is, how well does a test of hypnotisability actually measure level of
hypnotisability. There are numerous other types of validity, and we shall refer to just two more:
convergent validity where scores on ‘the’ measure converge (or correlate) with another test
known to measure the same construct and, divergent validity, where ‘the’ test scores diverge (or
fail to correlate) with a test known not to measure the same construct.
The most commonly reported validity coefficients are factor coefficients which relate to the
clusters (or factors) of abilities referred to above (for a fuller discussion see texts referred to in
Footnote 1) and correlations between two tests: ‘the’ test under investigation and another. For a
Clinical applications of hypnotic assessment Moore & Powlett
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test to be valid it needs to correlate highly with other tests assessing the same or similar construct
and/or it needs to correlate with the behaviour or ability. Conversely, correlations between ‘the’
test and those assessing different constructs should yield low correlations. Before presenting an
overview of some of the many tests of hypnotisability, it is important to briefly refer to some of
the major ethical, and following on from this legal, issues involved in testing (see your own
professional code for a complete guide).
Ethics
Before commencing testing, participants should be fully informed about the nature of and the
reasons for the testing and, in cases where the results may be used for research purposes,
informed consent must be obtained. Naturally an appropriate setting must be provided and
participants should be assured of the anonymity and confidentially of their results. The persons
undertaking the testing will be appropriately qualified and in the case of testing for
hypnotisability, the participants will have been appropriately screened for contraindications such
as depression or psychosis. Although these criteria have always been part of good clinical
practice, following the Rogers v Whitaker (175 CLR 479) decision in Australia in 1992 there is
now a precedent for legal challenge.
Since this case, there has been a shift from the English tradition of emphasing duty of care to
American law in which the patient’s rights are the central issue in patient-therapist interactions.
This case highlighted that an essential component of consent is the discussion of risks and for
this a good history is necessary. In the process of obtaining the history and discussing the risks,
documentation of the discussion is essential and this needs to met two goals. First, that both
therapsit and client have the same understanding of what is expected from the hypnosis sessions,
in terms of benefits, and in terms of risks and costs. The second goal is that consent is
documented in such a way that a third party such as a juror can decide what was said and
understood (Put simply, ‘no notes equals no defence, poor records equals poor defence)
(extracted with permission from White, 1997).
Measuring Hypnotisability
Ledford, Brazleton and Shannon (1995) and Horne and Powlett (1988) recognised that both
interest in the assessment of hypnotisability, and measures of hypnotisability, are relatively
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recent phenomena, with most scales having been developed since the 1970s. The measurement
of hypnosis typically, though not always, involves a standardised induction technique.
Following induction, which Spiegel and Spiegel (1988) suggested follows one of three major
styles: coercion, seduction, or guidance, the individuals being assessed are asked to engage in a
number of known hypnotic phenomena. Their ability to perform these is rated and said to
represent their level of hypnotisability. Most scales include items of both behavioural and
cognitive components, such as, hand lowering/raising, age regression, and hypnotic amnesia. The
more items passed, on what are said to be graded levels of difficulty, the more susceptible the
subject is said to be (Hilgard, 1965).
Scales
Although not all tests presented below require an induction procedure, authors such as Hand,
Pekala and Kumar (1995) have suggested that it is not possible to assess hypnotic susceptibility
unless the Harvard or Stanford [or equivalent] induction procedures are administered within that
framework. That this is a somewhat circular process may have contributed to recent focus on
assessment of the phenomena of hypnosis that individuals are able to engage in (eg., time
distortion, movement) as indicators of hypnotic ability rather than global scores. Of the
following tests of hypnotisability, the Stanford, Harvard, and HIP scales require highly trained
staff to actually induce hypnosis before any assessment occurs.
Stanford Hypnotic Susceptibility Scales, Forms A and B (SHSS: A & B) (Weitzenhoffer &
Hilgard, 1959, 1962) are alternate forms of same scale which are individually administered over
a 50-minute period. SHSS (A & B) are designed to screen subjects into low, medium, and high
susceptibility. They comprise 12 items with the emphasis skewed towards motors items (eg,
postural sway, eye closure, hand lowering) rather than cognitive dimensions (eg, fly
hallucination, posthypnotic suggestion, amnesia). Horne and Powlett (1988) suggested that
because of the overestimation on motor behaviour, these scales do not sample widely enough
from the range of hypnotic behaviours.
Form C of the Stanford Hypnotic Susceptibility Scale (SHSS:C), whilst designed to overcome
these limitations and include more cognitive items dealing with age regression, dreaming, and
positive and negative hallucinations across a number of sensory modalities (visual, auditory,
gustatory, and olfactory), it still requires hypnotic induction and takes some 45-50 minutes to
Clinical applications of hypnotic assessment Moore & Powlett
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administer on an individual basis. Forms A, B and C of the Stanford Hypnotic Susceptibility
Scale have been further supplemented by Profile Forms 1 and 11 which are generally only
administered to people achieving a certain score on any of Forms A, B, or C. These profiles
reveal people’s particular areas of hypnotic susceptibility and, as a result, are said to be useful in
matching subjective hypnotic abilities to research or even therapy requirements.
Harvard Group Scale of Hypnotisability (Shor & Orne, 1962, 1963) is a modified version of the
Stanford Susceptibility Scale, Form A, developed to assess a large number of subjects within a
group setting. Subjects are subjected to a standardised group induction process and, following
the trance state, they are asked to report on a 12-item scale about their experience. People scoring
0-4 on the 12-point scale are said to be low susceptibility, those 5-7 are moderate, and those 8-12
are regarded are high susceptible to hypnosis (Pettinati, Kogan & Evans, 1990). Ledford et al.,
(1995) reported high internal consistency (.91, n=280). The Harvard scale also takes some 50
minutes to administer, plus the time necessary for highly trained personal to establish rapport
with and debrief subjects. While the literature does not appear to contain any account of
participants, especially more than one simultaneously, experiencing an abreaction during group
testing, the possibility of this negative consequence and the implications for all participants in
the session, can not be ignored.
Horne and Powlett (1988) suggest the Harvard also contains more motor items than cognitive
ones. This bias, together with the fact that the Harvard Group scale was based upon the SHSS.A,
will explain its moderate to high correlation with that Stanford Scale (r=.59, Evans &
Schmeidler, 1966; r=.81, Ledford et al., 1995).
Hypnotic Induction Profile (HIP) (Spiegel & Bridges, 1970; Spiegel & Spiegel, 1978) this scale
is purported to tap individuals basic trance capacity as well as their ability to use hypnosis. The
authors argue its clinical use is also enhanced by its brevity of administration (approximately ten
minutes) and its sensitivity to the hypnotic process itself. The HIP has 12-items, four of which
involve eye movement: upward gaze, roll, squint, and then the rater scores for eye-roll sign
which is a composite of scores from the eye roll and squint; arm levitation, tingle and
dissociation - where the subject is asked whether this arm is ‘ as much a part of your body as’ the
other arm; control differential - where subject is asked to differentiate between the amount of
control in one arm (not leviated) and the other arm (leviated); cut-off - which relates to the
resumption of ‘normality’; amnesia to cut-off - where subject is aware that differential control is
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now gone, and they are asked why this is so; floating sensation - rated on subject’s perception of
lightness during leviation. A detailed administration and scoring system is provided and includes
an instruction to monitor the time and amount of re-inforcers used throughout the testing. While
test-retest reliability reported by the authors is good (.76 for a group of 75 psychiatric patients),
unless other administrators are highly-trained and adhere strictly to the instructions and scoring,
results may be less consistent.
Barber Suggestibility Scale (Barber, 1969) - devised to test hypnotic behaviours with or without
the induction of hypnosis. The scale may be administered under imagination or motivational
conditions, as well as under hypnosis. Such a comparison (imagination versus hypnosis)
supposedly makes it possible to measure the increase in hypnotic responsiveness due to the
hypnotic induction. The principle of change or gain scores has also been advocated by
Weizenhoffer (1980) in relation to the Stanford Scales, although Hilgard has rebutted this
approach.
More so than other scales, the Barber scale heeds the subjective experiences of the subject in the
objective scoring of the responses. Without consideration of the timing prior to instructions or
for the induction of hypnosis or for any debriefing, it is reported that the test takes, on average,
12 minutes to administer. There are eight items which are: arm lowering, arm levitation, hand
lock, thirst ‘hallucination’, verbal inhibition, body immobility, ‘posthypnotic-like’ response, and
selective amnesia. Test-retest reliabilities of the scale have ranged from r.80 to r.88 (Barber,
1969).
Creative Imagination Scale (CIS) (Wilson & Barber, 1976) can be administered individually or
to a group with or without a prior hypnotic induction procedure. The CIS consists of ten items
(test suggestions) the aim of which are to get subjects to produce the suggested experiences by
their own thinking and creative imagination rather than as a result of being under the instruction
of the hypnotist. Administration of the test takes about 18 minutes. Subjects are asked to close
their eyes and keep them closed during administration of the scale. The test suggestions in the
order they are presented are: arm heaviness - imagine left-arm extended and three heavy
dictionaries are placed on the hand making it heavy; hand levitation - right arm extended and
water from garden hose is directed onto palm and pushing arm upwards, finger anaesthesia -
imagine Novocaine injected into side of hand and numbness spreading through fingers, water
‘hallucination’ - drinking a cup of cool mountain water; olfactory-gustatory ‘hallucination’ -
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imagining the smell of an orange; music ‘hallucination’ - guiding the subject to re-experience
some wonderful music; temperature ‘hallucination’ - imagine sun shining on hand and making it
feel hot; time distortion - time slowing down; age regression - feeling and experiences as a child
in primary school; and mind-body relaxation - lying relaxed in the sun on the beach. Subjects
indicate their responses on a written questionnaire with each response evaluated on a five-point
scale 0 Not at all the same to 4 Almost exactly the same as if real.
Wilson and Barber (1978) reported the CIS was unifactorial using Principal Components
Analyses with 217 subjects, test-retest on twenty-two subjects was r.82 (p<.01), and split-half
reliability was r.89 (p<.001). These authors cite an earlier unpublished study by Kiddoo (1977)
wherein the CIS and the Barber Suggestibility Scale correlate moderately at .60 suggesting
convergence of content. Myers (1983) tested 1302 children on their responsiveness to the CIS
and concluded that it is stable for children from 9 years onwards. She does, however, suggest
that it be individually administered to children between 12 and 15 years to avoid possible peer
pressure.
The Diagnostic Rating Scale (Orne & O’Connor, 1967) was devised for the purpose of
quantifying hypnotic susceptibility on the basis of clinical data as judged by experienced
hypnotists. It is said to have the advantage of producing a rating based upon an evaluation of the
subject using hypnotic techniques best suited to them as individuals, rather than restricting the
hypnotist to a standard set of items which would not allow the therapist to maximise the effect
for a particular subject. One disadvantage is that it can only be used by highly trained staff and
because it is not standardised, there may be little or no inter-rater reliability, thus precluding the
obtainment of an objective score.
Stanford Hypnotic Clinical Scale SHCS (Morgan & Hilgard, 1975) was also developed for
patients in a clinical setting and takes 20 minutes to administer, including a hypnotic induction.
The authors maintain that it does not tire patients, is adaptable to patients with restricted
mobility, and taps the kind of processes most likely to be used in therapy. It has five items
modified from the earlier Stanford Scales: someone who passes four of the five items is
considered to be highly hypnotisable. Morgan and Hilgard (1975) found a product-moment
correlation of .72 between the total score on the SHCS and the total score on the SHSS Form C.
The corresponding correlation between the four items common to both of these scales was .81.
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Carleton University Responsiveness to Suggestion Scale (CURSS) (Spanos, Radtke, Hodgins,
Stam, & Bertrand, 1983) is a seven-item scale designed to assess responsiveness to suggestions
associated with hypnotic susceptibility including: two ideo-motor items (arm levitation, arms
moving apart), two motor-challenge items (arm rigidity, arm immobility, and three cognitive
items (auditory hallucination, visual hallucination, amnesia). Subjects receive two scores: a
CURSS-O or observer rating which is said to be objective, and their own CURSS-S which is
subjects’ own subjective rating of their performance following hypnotic induction. It is unclear
what any gap represents. Spanos, Radtke, Hodgins, Bertrand, Stam and Dubreuil (1983) report a
coefficient of reproducibility of .86 for objective scoring.
Other more specific observer-rated scales have been developed (eg., The University of Tennessee
Hypnotic Susceptibility Scale for the Deaf (Repka & Nash, 1995) and the Children’s Hypnotic
Susceptibility Scale (London, 1963), for children, with each requiring highly trained staff and
time to administer them.
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Assessing Self-Hypnosis
Although controversy exists concerning the level of hypnosis or depth of hypnotic trance which
can be attained with self-hypnosis, Shor and Easton (1973) developed a test to measure this
phenomena.
Inventory of Self-Hypnosis (ISH) Shor and Easton (1973) was developed to compare self-
hypnosis and hetero-hypnosis as measured by the Harvard Group Scale of Hypnotisability, Form
A of Shor and Orne (1962). Shor and Easton’s data suggest that the ISH and HGSH:A measure
different phenomena but Johnson and Weight (1976) found that, in general, self- and hetero-
hypnosis were phenomenologically and behaviourally similar. Responsiveness to individual
items that were comparable on both scales, however, varied according to the scale used. Fromm
(1975) also compared ISH and HGSH:A and found more hypnotisable subjects reported
phenomenological differences between the two experiences. These subjects experienced more
ego splits, visual imagery, and idiosyncratic fantasy during self-hypnosis than during hetero-
hypnosis.
Self-report Assessment
Extended North Carolina Scale (ECNS) (Tart, 1978) is a self-report scale of hypnotic depth. It is
criticised because estimates made by subjects are not really spontaneous, as specified in the
instructions, but are tied to the success or failure of the immediately preceding hypnotic
phenomena. However, Kahn, Fromm, Lombard and Sossi (1989) reported a correlation of r.61
(n=22, p=.002) between the ENCS and hypnotisability as measured by the Stanford Profile Scale
of Hypnotic Susceptibility, Form 1 devised for highly hypnotisable subjects, and concluded this
result lent validity to the ECNS as a measure of self-hypnotic depth.
Page and Handley (1996) suggest that subjects’ retrospective ratings of the realness of the experience of
arm rigidity and eye catalepsy during the Harvard Group Scale of Hypnotic Susceptibility (Form A),
together predict the total Harvard score (R2 38%) sufficiently to be used as a brief, inexpensive,
preliminary screening device. These authors acknowledge that this method may misidentify high or
medium subjects as low, however, they also argue that because their questions relate to the realness
factor (ie. compared to what you would have experienced if your arm/eyes tightly glued, what you
experienced was 0 Not at all the same to 4 Almost exactly the same) this removes much potential for
subjects to experience failure.
Commonality amongst Scales
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Several scales have been based upon the Stanford Scales and it is, therefore, not surprising that newer
scales would converge on these or on other derivatives. What seems important to extract from the
scales’ content is the commonality amongst the phemonema assessed: cognitive items, motor items, and
behavioural items. It follows that client performance on any or all of these domains may help, not only
to indicate level of hypnotisability, but rather the specific areas in which the client is ‘proficient’. It also
follows that these domains might be best utilized within a therapeutic context for that particular client
while ‘training’ might occur with other domains as and if necessary. While it is outside the range of this
paper to discuss this aspect further the reader is referred to authors who have successfully used the
Carleton Skills Training Program (eg., Bates & Kraft, 1991; Robertson, McInnes & St Jean, 1992).
Related Assessment
Phenomenology of Consciousness Inventory (PCI) (Pekala, 1991a&b; Pekala & Kumar, 1984)
has been used in the prediction of hypnotic susceptibility as measured by the Harvard Group
Scale of Hypnotic susceptibility of Shor and Orne (1962). The PCI is a 53-item self-report
inventory that is completed retrospectively in reference to a preceding stimulus condition. There
are 12 major and 14 minor dimensions of consciousness that assess specific areas of
phenomenological experience. These dimensions include: positive affect (joy, sexual excitement,
love), negative affect (anger, fear, sadness), altered experience (body image, time sense,
perception, unusual meanings), attention (direction, absorption) imagery (amount, vividness),
internal dialogue, self-awareness, state of awareness, memory, rationality, volitional control, and
arousal. The PCI has been shown to have adequate construct, discriminant (eg, Kumar & Pekala,
1988; Pekala & Kumar, 1984) and predictive validity (eg, Forbes & Pekala, 1993; Pekala &
Kumar, 1984).
Whilst at first reading, the PCI seems to be a self-report indicator of future hypnotisability, it is
not. The focus of the scale is actually embedded within the hypnotic trance and the subsequently
obtained scores for both the PCI and either the Harvard or Stanford are used as predictor and
outcome variables respectively. In other words, after the induction phase the hypnotist pauses
part way through the assessment of either the Harvard or Stanford scales and asks people to
experience a four-minute period during which they are told ‘to continue to experience the state
you are in right now. For the next several minutes I’m going to stop talking and I want you to
Clinical applications of hypnotic assessment Moore & Powlett
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continue to experience the same state you are in right now’. These instructions are repeated once.
Then silence for four minutes.
After de-induction, and writing reports of what they remembered from the Harvard (or observer
ratings from the Stanford) subjects are asked to complete the PCI in relation to their thoughts and
feelings during the four-minute interval. Pekala and colleagues stated that this is a valid indicator
of people’s level of hypnotisability as the scores from the PCI predict scores on both the Harvard
and the Stanford. Whilst this may be statistically true, the PCI is clearly not an a priori predictor
of hypnotisability and, as such, is somewhat disappointing in its claims to predict a state it
actually reflects upon and within.
Dissociation
The Dissociative Experiences Scale (DES; Bernstein & Putnam, 1986) has three factors: absorption,
amnesia, and depersonalization (Frischolz, Braun, Sachs, Schwartz, Lewis, Shaeffer, Westergoord &
Pasquotto, 1992). Internal reliability for each of the factors range from α .77 to .90, stable across normal
and clinical samples. The first factor is said to represent normal dissociative experiences and it correlates
with the Tellegen Absorption Scale (TAS) between .40 to 82 (Frischolz, Braun, Sachs, Schwartz, Lewis,
Shaeffer, Westergaard & Pasquotto, 1991; Nadon, Hoyt, Register & Kihlstrom, 1991).
Attempts to correlate the DES with measures of hypnotisability have yielded correlations between r.12
against the Harvard Group Scale of Hypnotic Susceptibility, and r.13 against self-ratings of
hypnotisability. Although Frischolz et al., (1992) suggest these correlations are of a similiar magnitude
to those obtained with the TAS, this appears not to be so (see below).
Absorption
Absorption is the degree to which people invest in imagination activities such as daydreaming,
novel reading, and poetry (Tellegen, 1979; Tellegen & Atkinson, 1974). It is a “disposition for
having episodes of ‘total’ attention that fully engage one’s representational (ie, perceptual,
enactive, imaginative, and ideational) resources” (Tellegen & Atkinson, 1974, p.268). In
practical terms, Frischoltz, Spiegel, Trentalange and Spiegel (1987) stated that absorption is the
ability to become immersed in thoughts, images, or tasks. Shor (1962) and Tellegen and
Atkinson (1974) demonstrated that individuals who prove on formal testing to be highly
hypnotisable report the occurrence of hypnotic like experiences in everyday life, which includes
a capacity for intense absorption in the subject at hand.
Clinical applications of hypnotic assessment Moore & Powlett
15
The absorption scale most commonly used, the Tellegen Absorption Scale (TAS) (Tellegen &
Atkinson, 1974), is a 34-item True/False questionnaire for which a summated score is most
frequently reported. It does, however, yield factors which load highest on: 'Reality Absorption,
Fantasy Absorption, Dissociation, and Openness to Experience, with Devotion/Trust and
Autonomy/Critically showing somewhat lower salient loadings' (Tellegen & Atkinson, 1974,
p.271).
Research examining the relationship between hypnotisability and absorption, where the latter
was viewed as ‘hypnotic-like’ experiences occurring in everyday life (eg, Hilgard, 1970; Kumar
& Pekala, 1988; Radtke & Stam, 1991; Glisky, Tataryn, Tobias, Kihlstrom & McConkey, 1991;
Tellegen & Atkinson, 1974) have all, with the exception of Spanos, McPeake and Churchill
(1976), found significant positive correlations ranging from r=0.22 to r=0.43. Hoyt, Nadon,
Register, Chorny, Fleeson, Grigorian and Otto (1989) investigated absorption and daydreaming
as correlates of hypnotisability and, while these two dimensions were themselves correlated (r.49
to r.66) only absorption as measured by the revised Tellegen Absorption Scale was correlated
with hypnotisability (r.22 with HGSH:A and r.26 with SHSS:C, both p<.001, n=955).
Despite the statistical significance of these correlations, it must be noted that the co-efficient of
determination (r2) which indicates the variance shared between measures of hypnotisability and
absorption range from 5 to 18 per cent. The obverse of this, is to acknowledge that between 82
and 95 per cent of the variance in hypnotisability is explained by factors other than absorption.
This poor relationship may be explained in part by the typical use of summated scores from the
TAS. Clearly, if a one-factor solution is used when in reality multiple factors exist then the true
relationship with other variables may be truncated. Further attenuation may occur if, as Glisky et
al., (1991) suggest, there are gender differences in the correlations between hypnotisability and
absorption. However, even accounting for these possibilities and some level of measurement
error, it is probable that these correlations will still fail to reach a practical level of significance.
Absorption, as measured by the TAS, appears to be unaffected by social desirability, locus of
control, State-Trait anxiety and is unrelated to extroversion and neuroticism, the two major
dimensions running through most personality inventories. While originally defined as an
openness to involving and self-altering experiences (Tellegen & Atkinson, 1974) absorption has
also been described as ‘a state of receptivity or openness to experiencing in the sense of
Clinical applications of hypnotic assessment Moore & Powlett
16
readiness to undergo whatever experiential events, sensory or imaginal, that may occur, with a
tendency to dwell on, rather than go beyond, the experiences themselves and the objects they
represent’ (Tellegen, 1979, p.222). In this sense, Glisky and Kihlstrom (1993) suggested that
absorption may be conceptually related to the openness to experience which is one of the
personality dimensions from the currently widely accepted Big Five personality structure of
Goldberg (1990).
Openness to experience
This personality style has been defined as ‘rich fantasy life, aesthetic sensitivity, awareness of
inner feelings, need for variety in actions, intellectual curiosity, and liberal value systems’
(McCrae & Costa, 1984, p.145). Correlations between openness to experience and absorption in
the order of r.56 (n=48; McCrae & Costa, 1984) and r.62 (n=186; Radtke & Stam, 1991) have
been reported. Radtke and Stam also investigated the relationship of these two factors to
hypnotisability and while absorption demonstrated a typical level of relationship (r.22), openness
to experience did not (r-.01).
However, Glisky et al., (1991) commented that openness to experience is itself heterogeneous,
and therefore it should not be expected that all of its factors would be related to absorption let
alone to hypnotisability. They described two separate statistically derived constructs making up
the personality dimension of openness: 1) relates to aesthetic sensitivity, unusual perceptions and
associations, fantasy and dreams, unconventional views of reality, and awareness of inner
feelings (openness) and 2) the Liberalism factor measuring intellectual curiosity, openness to
unusual ideas, need for orderly thought, variety in actions, and liberal values. They then reported
that absorption (r.17) and openness to experience (r.16) correlated with hypnotisability while
Liberalism did not (r.10). However, it is clear that both absorption and openness explain less than
3 per cent of shared variance with hypnotisability.
In an extension of this work, Kihlstrom, Glisky and Trapnell (1992 unpublished manuscript cited
in Glisky, Tataryn, Tobias, Kihlstrom & McConkey, 1991) used the 36-item measure of
absorption, intellectance (openness) and liberalism, together with a tape-recorded version of the
Harvard Group Scale of Hypnotic Susceptibility, Form A (HGSHS:A; Shor & Orne, 1962) and
confirmed that while absorption and intellectance (openness) correlated with each other (r.41),
absorption and hypnotisability correlated less so (r.15) and intellectance not at all (r.05). Before
discrediting the theoretical proposition that the personality dimension of openness is related to
Clinical applications of hypnotic assessment Moore & Powlett
17
hypnotisability, it is important to note that the 3-factor structure of the newly evolved
questionnaire was not confirmed. It may be that poor structure contributed to an attenuation of
the intercorrelations amongst openness, absorption and hypnotisability. Despite the generally low
correlations between hypnotisability and absorption each of these variables correlates at
approximately the same, albeit higher, level with imagery vividness.
Imagery
Imagery is widely accepted as representing an important dimension of hypnosis. Heyneman
(1990) suggested that visual imagery is usually experienced as a quasi-perceptual phenomenon
somewhat akin to a limited resolution ‘mental picture’, although this metaphor fails to take into
consideration other types of imagery, for instance, auditory, cutaneous, kinaesethic. Researchers
have developed a number of assessment devices which attempt to assess the qualities of mental
imagery such as vividness, controllability, or ease of creation of the mental image (eg, Betts,
1909/Sheehan, 1967; Gordon, 1949).
One understanding of the relationship between hypnosis and imagination argues that
‘imaginative involvement constitutes a generalised cognitive ability central to the performance of
hypnotic tasks’ (Spanos & McPeake, 1974, p.689). Thus K. S. Bowers (1992) says it is virtually
de rigueur to invoke some relevant imagery or imagined state of affairs as part and parcel of a
hypnotic suggestion. Certainly, the hypnotist uses the words imagine your hand is ... (p.255)
which may promote visualisation of the scene or may, at a more concrete and perhaps exact level
of instruction, access kinaesthetic imagery.
The relationships between absorption and imagery vividness (eg., P. Bowers, 1978; Monteiro,
MacDonald, & Hilgard, 1980; Pekala, Wenger, & Levine, 1985; Richardson, 1983) and between
hypnotisability and imagery vividness (eg., Priebe & Wallace, 1986; Sutcliffe, Perry & Sheehan,
1970) range between r=0.34 and r=0.39, with the exception of Richardson (1983) who reported a
correlation between the TAS and the Questionnaire upon Mental Imagery (QMI) (Betts,
1909/Sheehan, 1967) of r=0.52, p<.05 for male, and r=0.55, p<.001, for female samples. The
effect of gender upon the relationship between imagery ability and hypnotisability is clearly not
resolved as others, for example, Sutcliffe et al., (1970) found a significant relationship for men
while Hilgard (1979) found an effect for females.
Clinical applications of hypnotic assessment Moore & Powlett
18
Using a different system, Lombard, Kahn and Fromm (1990) classified imagery as either reality-
oriented or fantastic with primary process qualities. Over a 4-week period of self-hypnosis they
found that, while levels of imagery remained constant for all subjects, females reported higher
levels of imagery especially for fantastic imagery. Lombard et al. also found that fantastic or
primary process imagery correlated with Impulse Expression (individuals’ ability to tolerate and
express their impulse life) (r.76 ) and with Outgoingness (which describes individuals who are
forceful, dramatic, and enjoy risk-taking adventures) (r.61) for females only.
P. Bowers (1982) used the Vividness of Visual Imagery Questionnaire (VVIQ) of Marks (1973)
and found it correlated .31 (n=42) with the Harvard Group Scale and .37 with the Stanford as
adapted for groups by Sanders and Schubot (1969, cited in Bowers, 1982). Dywan (The imagery
factor in hypnotic hypermnesia) also used the VVIQ and found it correlated .17 (n=54, p>.05)
with the SHSS. Clearly the results produced using Mark’s VVIQ, which incidentally draws some
of its items from the QMI, are not comparable. It is interesting to speculate what the relationship
with hypnotisability would be for the items common to the QMI and the VVIQ and those unique
to each scale.
Parallel with Tellegen and Atkinson’s (1974) term absorption to describe people’s capacity for
total involvement in a task or event, in the same year Spanos and Barber (1974) noted that
imaginative involvement is the only personality trait consistently related to hypnotic
susceptibility. Baum and Lynn (1981) and Fellows and Armstrong (1977) found that subjects
who are more highly hypnotisable are also more engrossed in imaginative reading material than
less hypnotisable subjects. Baum and Lynn also demonstrated that there was no difference
between these groups when examined on non-imaginative material about deserts and biological
clocks drawn from the World Book Encyclopedia. It is, however, unclear what uniquely
separates imaginative involvement and absorption either theoretically or empirically.
People who cannot use visual imagery may achieve comparatively low scores on the Creative
Imagination Scale (Wilson & Barber, 1976) on the Stanford Hypnotic Clinical Scale (Morgan &
Hilgard, 1975), and yet be capable of experiencing considerable trance depth and success on
other items such as response to posthypnotic suggestion. Similarly, Zamansky and Clark (1986)
found that it was not necessary to be fully absorbed in the direct suggestions of the hypnotist to
perform those suggestions successfully. Alternatively, Forbes and Pekala (1993) suggested that
Clinical applications of hypnotic assessment Moore & Powlett
19
because of the ability of some individuals to elicit vivid imagery without an induction, hypnosis
may not add a great deal to what they can experience by merely closing their eyes.
Relevance of Related Phenomena to the Clinical Situation
The phenomena of absorption, dissociation, openness to experience and imagery can be used
jointly or separately to help explain the phenomena of hypnotisability to the client. This can be
facilitated by drawing upon ‘everyday’ experiences and so demystifying the process and perhaps
assisting the client to be more receptive to the effects of the hypnotic experience. At a global
level, client identification with any or all of these phenomena may be all that is available or
possible in an emergency situation when other, more stringent testing is not feasible.
Despite the statistical and, it seems practical, links between hypnotisability and imaginative
involvement others, for example, Council, Kirsch and Hafner (1986) suggest that this link may
be mediated by context-based expectancies. They found that when an hypnotic scale and the
TAS were administered in the same testing context, correlations were substantial, however, when
the testing contexts were separate, the measures failed to correlate. Even if this explanation is
robust, we do not believe that it is not necessarily detrimental to effective treatment using
hypnosis.
Clinical applications of hypnotic assessment Moore & Powlett
20
Suggestibility
Weitzenhoffer (1980) described the classic suggestion effect in hypnosis as requiring two criteria
to be met: 1) there must be a response to a suggestion, 2) which is experienced as nonvolitional.
How much of what is termed hypnotic response is nonvolitional, and how much is influenced by
the subject’s suggestibility or, as has been the focus of much work, simulation? While it is
outside the parameters of this work to address issues related to simulation, it is important to
address the issue of suggestibility. Gudjonsson and Clark (1986) defined interrogative
suggestibility as ‘the extent to which, within a closed social interaction, people come to accept
messages communicated during formal questioning, as the result of which their subsequent
behavioural response is affected’ (p.86).
Field (1973) surveyed words used during hypnotic induction and found a high frequency of the
words will, as, and the verb to be. He suggests that the use of the word will may be explained in
terms of the future tense involved in hypnotic induction and the creating of belief and
expectations in the subject (eg, in a moment, you will feel you hand ...; you will see ...).
Most studies attempting to assess levels of suggestibility use film, however, Gudjonsson (1984)
developed the Gudjonsson Suggestibility Scale (GSS) which uses a narrative paragraph about a
fictious mugging which is read aloud to the subject. The subject is then asked to repeat all that is
remembered about the story (immediate feedback) and then some 50 minutes later is again asked
to recall the story. At the later time, negative feedback is provided and the subject once again is
asked to answer the same questions. The objective of this testing is to assess the consistency or
suggestibility of answers following the negative feedback. The GSS yields two factors: the extent
to which subjects yield to subtly leading questions and secondly, the extent to which subjects
shift their replies once interpersonal pressure is applied. A parallel version of the GSS (the
GSS2) (Gudjonsson, 1987) also uses narrative which is confounded by subsequent negative
feedback. However, this type of testing is both time consuming and not amenable to self-report
surveys. And, although referring to eye witness testimony, Sheehan and Linton (1993)
questioned whether subjects actually acquiesce to suggestions or are susceptible to suggestion.
Confounding of Expectations and Suggestibility
Clinical applications of hypnotic assessment Moore & Powlett
21
Katsanis, Barnard and Spanos (1988) developed the Carelton University Responsiveness to
Suggestion Scale (CURSS) Self-Prediction Questionnaire to be answered by subjects before
completing the CURSS itself. The self-prediction scale gives a brief description of each CURSS
item and then asks subjects to rate their future performance on each of the items. For example,
following a description of the CURSS arm levitation suggestion, subjects are asked to state
whether
A My arm will have risen at least 6 inches
B My arm will have risen less than 6 inches.
Respondents are rated Pass or Fail and the sum of responses ranges from 0 to 7 (None Passed to
All Passed).
This situation is both linguistically and cognitively complex. How does one differentiate the
motive behind answers to these questions: do the answers reflect self-expectations about future
performance or, do they more accurately reflect a response bias based upon suggestibility
provoked by the content of the questions? In both cases, answers may be further contaminated by
subjects prior knowledge of hypnosis which is frequently based upon erroneous accounts of
others or even from observations of stage or television hypnosis.
Other studies have manipulated subjects by providing people with false feedback regarding
personality inventories (eg., Gregory & Diamond, 1973) and false reports about physiological or
sensory feedback (eg., Wickless & Kirsch, 1989) or both (eg., Johnston, Chajkowaski, DuBreuil
& Spanos, 1989) which were also said to indicate subjects level of hypnotisability. Perhaps it
would be just as informative to have people rate their own level of (future) hypnotisability and
ascertain if this self-report value, driven by subjects’ own experiences, fears, and expectations,
exerts any effect on outcome. Kirsch (1996, 1997) is amongst those who have pointed out these
expectations may contribute to therapeutic outcome, albeit, via a placebo effect.
Hypnosis and outcomes
Despite the mechanisms at work, (eg a placebo effect, client suggestibility) Kirsch and colleagues (eg.,
Kirsch, 1990;Kirsh, 1996; Kirsch, Montgomery & Sapirstein, 1995) have clearly demonstrated via a
meta-analysis that cognitive-behavioural therapies were more effective than psychodynamic therapies
and, that by adding hypnosis to either of these further increased their effectiveness by a substantial
degree. The effect size for a combined cognitive-behavioural and hypnosis treatment averaged across
Clinical applications of hypnotic assessment Moore & Powlett
22
meta-analyses was 2.55. Perhaps a more concrete illustration of this effect is to describe it as the degree
of improvement in untreated people being surpassed by the typical client receiving CBT+hypnosis in
99.5% of cases. To counter the argument that it was not just relaxation that impacted upon these results
Kirsh (1996) pointed out that 1) the effect size for hypnosis is greater than for relaxation and 2) even an
active-alert induction of hypnosis (see Banyai & Hilgard, 1976) demonstrates a similar positive effect.
It seems somewhat truculent to point out that these findings are only available via the application
of the scientific method which necessarily includes assessment and evaluation. Not only do these
findings confirm results for these particular cohorts of patients but, again using scientific
principles, they indicate that these results are generalizable to other clients with similar levels of
hypnotic ability. Yet, despite demonstrations such as this of the efficacy of hypnosis as a
therapetic modality and the availablility of a range of tests, it seems that many therapists fail to
assess their clients’ hypnotisability in any manner whatsoever.
Clinicians: Users of hypnotic assessment?
A survey of participants attending an American Society of Hypnosis workshop, of whom 47%
were clinical psychologists, 34% physicians, and 18% dentists, revealed that 46 per cent of the
respondents had never used tests of hypnotisability in their clinical practice. These practitioners
considered testing to be of no value in their practices and, furthermore, that the degree of
hypnotisability did not correlate with their therapeutic results - their prime concern (Cohen,
1989). Of the other 54 per cent of therapists who reported some use of tests of hypnotisability,
24% of this group reported having currently abandoned testing. In fact, only 30 per cent of
experienced therapists attending this workshop reported the ongoing use of hypnotic assessment.
Cohen summarized this report by stating the ‘majority of experienced clinicians not only eschew
formal testing, but many consider testing to be nontherapeutic and irrelevant’ (p.7). It is,
however, not clear from this article, how these particular therapists gauged the degree of
hypnotisability, or indeed, their therapeutic outcomes, without some form of assessment. In fact,
Hilgard (1982) described ‘this lack of research to support the claims of some clinicians as
shocking’ (p.395).
This report stimulated a great deal of comment. On the side of ‘art not science’, Diamond (1989)
stated that in the clinical domain testing ‘either fails to enhance, or, worse yet, detracts from my
clinical aims as a psychotherapist’ (p.11). Diamond’s focus, he says, is on the interactive
Clinical applications of hypnotic assessment Moore & Powlett
23
relationship with the client and facilitating dynamic change: he is not comfortable using his
client for ‘research purposes’. It is not clear how Diamond assesses such therapeutic change, if
not by the most basic experimental/research design of pre- post-evaluation. How he attributes
causality to any or all of the therapies he employs is also unclear unless based upon scientific
(albeit in a clinical context) observation. It might also be expected that, as a clinician, Diamond
would extract from successful sessions and employ these techniques with other clients - a
process quite valid for testing the robustness of the techniques or, in research terms, their
generalization.
Contrary to this perspective, Barber (1989) stated that a test of hypnotisability provides a probabilistic
estimate of responsiveness; [although] it cannot tell us anything about an individual’s actual capacity
for responsiveness (p.10), as in fact, the testing and therapeutic conditions may be quite different.
Despite the possibility of this discrepancy, it is clear that Barber advocates testing. How else, he
demands, can causality be attributed, therapists communicate with one another or with the scientific
community about their results, and how else can hypnotic treatment become more reliable and efficient?
Rather than focusing on the polarities suggested by each of these protagonists, it may be preferable to
outline a clinician’s perspective in relation to client interview, assessment, and treatment.
A clinician’s perspective
When clients present for treatment, it is the clinician’s responsibility to obtain a full history in order to
inform diagnosis and future treatment. Questions which arise from this premise are 1) is the diagnosis
within your professional capacity, 2) have you the skills to utilize the most appropriate treatment and 3)
is the client a suitable candidate for this particular therapy. Further referral or treatment alternatives
depend upon these answers.
Let us assume that a diagnosis has been made, there are no contraindications and the use of
hypnotheraphy is considered as a possible treatment adjunct. How does one know this (or any other
treatment) will be effective with this client. Firstly, good practice requires the client to be fully informed
about the nature of the treatment (i.e.,hypnosis) including any risks, and that informed consent for the
treatment is obtained. Hilgard (1982) has been quick to point out that it is only through measurement
and the scientific method that myths some clients hold about hypnosis have been able to be debunked.
For instance, myths such as success in hypnotizing relies on the skill of the therapist and conversely, that
Clinical applications of hypnotic assessment Moore & Powlett
24
focus (eg, on a thumbnail or place in space) is a satisfactory pathway into hypnosis and not the strain
associated with some eyeroll techniques.
Following this step, we believe it is ethically and professionally essential to ascertain if the client has the
potential to be responsive to the treatment (hypnosis)2and this step requires an assessment of the client’s
hypnotisability. Whilst a strong advocate of assessment, Hilgard (1982) says the choice lies between
clinical judgement of responsiveness and more scientific measurement but, some level of assessment is
required (and heeding the legal case presented above, this discussion must be clearly documented: and,
it seems, you must support why and how you judge hypnosis would be of therapeutic value for this
client).
Sacerdote (1982) also advocates the use of assessment in clinical applications of hypnosis, however, he
cautions that most hypnotisability scales [because of their standardization] miss the opportunity for
nonverbal communication, for the qualitative differences in the character and level of hypnotic
responsiveness. He also cautions against their carte blanche use. In doing this, Sacerdote cites the
example of a patient with metastic cancer who, he believes, well may have benefited from the relaxation
induction of the SHCS:Adult scale but not from the time or energy devoted to the five assessment items.
In fact, he believes that she probably would not have passed these and have been considered
unhypnotizable. If on the other hand he had used the HIP, the effort involved with the eye-roll
technique, might have seemed non-meaningful to her and again she may have been classified as
unhypnotizable. In order to establish some level of assessment to inform both himself and his patient,
Sacerdote used reverse hand levitation with this patient and, as well as avoiding distress for this patient,
this technique may well have enhanced the patient-doctor relationship. Clearly, good clinical practice
prevailed: the patient’s well-being was paramount yet, also relevant to her wellbeing was the
administration of a brief indicator of the viability of future treatment. This case provides an excellent
example of balance between clinical experience and scientific method with respect for the individual
involved.
It is also important to realize that some clients’ responses might be blocked by other phenomena.
For example, the first author assessed one client who ‘failed’ the amnesia test on the SCHS. Yet
in discussion following the assessment, the client revealed that there was a momentary blocking,
2 We have deliberately used the word treatment with hypnosis in brackets, as we believe the assessment of suitability
for hypnosis is equivalent to the assessment required for any other form of treatment (eg, a demonstration of high
blood pressure may preclude specific drugs)
Clinical applications of hypnotic assessment Moore & Powlett
25
but he had instructed himself not to forget. He was a physics teacher whose job entailed precise
attention to detail and instant recall of formulae. Clearly, appropriate assessment involves not
just testing but a thorough clinical understanding of the phenomena involved and the reactions of
each particular client.
This example, together with that drawn from Sacerdote, re-inforce the importance of clinical and
personal contexts. Why are these clients presenting now, what are their expectations of the
treatment, of the therapist, and indeed, what are the therapists expectations? If we the therapists,
are highly hypnotizable, if we can use imagery, it does not necessarily follow that our clients
have the same capacities. There is a need to assess what these capacities are for each individual
client and to tailor those capacities to therapy with or without the use of hypnosis.
Summary and Conclusions
Hypnotic techniques have demonstrated therapeutic efficacy over and above that achieved with
cognitive-behavioural techniques. The attribution of causality across treatment is only possible
because of the scientific evaluation of each treatment component: in the case of hypnosis, this
relies on the assessment of people’s hypnotisability. Numerous scales are available to test levels
of hypnotisability from clinician-rated to self-report and many of these have been reviewed. It is
important, as clinicians, that we not only keep abreast of the latest literature in our field, but that
in doing so we also ascertain whether clients are suitable for specific treatment modalities based
on the literature review and subsequent context-relevant clinical assessment of each client. It is
our contention that the phenomena of good clinical practice and valid clinical assessment, in this
instance, of hypnotisability, are not mutually exclusive. Barber (1989) was even more forceful in
this regard, as he stated:
Those who do not register trance capacity, need and deserve help - but
some other form of treatment like psychosocial supportive therapy,
pharmacological control ... They certainly should be spared the
disappointment and demoralization of useless, time-wasting hypnotic
rituals.
Clinical applications of hypnotic assessment Moore & Powlett
26
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Chapter
The Phenomenology of Consciousness Inventory (PCI) (Pekala, 1982, 1991b)1 is a retrospective self-report questionnaire completed in reference to a preceding stimulus condition. As with the Phenomenology of Consciousness Questionnaire (PCQ) and the (Abbreviated) Dimensions of Consciousness Questionnaire, (A)DCQ, the PCI permits subjective experience to be phenomenologically quantified in terms of pattern parameters, as Tart (1975) indicates, and intensity parameters, as Singer (cited in Zinberg, 1977), suggests, thus allowing for the phenomenological values associated with a given stimulus condition to be empirically assessed.
Article
The aims of the present study were to examine the relationship between the Harvard Group Scale of Hypnotic Susceptibility: Form A and the Stanford Hypnotic Susceptibility Scale: Form C, and to examine the effects of gender, handedness, academic major, and therapy history on hypnotic susceptibility. Results suggested a strong correlation between the two scales. Only gender correlated with hypnotisability, with female subjects being higher in hypnotic susceptibility than male subjects.
Article
Two studies assessed the effects of self-predictions and interpretations of suggested demands on hypnotizability. Subjects overestimated their responsiveness to suggestions. Those who believed that they would fail all or almost all suggestions invariably attained low hypnotizability scores. However, those who believed that they would be highly responsive exhibited wide variability in their actual hypnotizability. Among subjects who self-predicted high responsiveness, those who adopted a passive “wait and see” interpretation toward suggestions scored significantly lower in hypnotizability than those who believed that they should actively bring about suggested effects. Study 2 also found that the relationship between adopting an active interpretation and hypnotizability was moderated by subjects' level of imagery vividness. Theoretical implications are discussed.