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Source: Journal of Psychosomatic Research
Volume 51, Issue 5, Pages 679-686
Date: November 2001
URL: http://www.sciencedirect.com/science/journal/00223999
Information processing in chronic fatigue syndrome*1
A preliminary investigation of suggestibility
Jeannie D. DiClementi(a),(b), Karen B. Schmaling(c) and James F. Jones(d)
a Department of Psychology, University of Colorado at Denver, Denver, CO, USA
b Department of Medicine, University of Colorado School of Medicine, Denver,
CO, USA
c Department of Psychiatry and Behavioral Sciences, University of Washington,
Seattle, WA, USA
d Department of Pediatrics, National Jewish Medical and Research Center,
Denver, CO, USA
*1 This study was conducted at the National Jewish Medical and Research
Center, Denver, CO.
Corresponding author. Present address: Department of Psychology,
Indiana-Purdue University-Fort Wayne (IPFW), Neff Hall Room 388, 2101 East
Coliseum Boulevard, Fort Wayne, Indiana 46805-1499, USA. Tel.:
+1-219-481-6403; fax: +1-219-481-6972; email: diclemej@ipfw.edu
Received 4 October 1999; accepted 13 March 2001 Available online 26 November
2001.

Abstract
This study examines the effects of certain types of information processing on
the subjective experience of cognitive deficits in persons with chronic
fatigue syndrome (CFS). Two groups of participants, persons with CFS and a
group of healthy controls, were administered a symptom inventory and measures
of intellectual functioning, memory, automatic processing, and
suggestibility. The groups differed significantly on number and severity of
reported symptoms and on measures of global suggestibility and automatic
processing, but not on measures of intellectual functioning and memory.
Suggestibility was related to number and severity of reported symptoms, as
well as the inability to inhibit the automatic processing of information.
Implications of these findings are discussed, as well as directions for
future research and treatment of symptoms associated with CFS.

Introduction
Chronic fatigue syndrome (CFS) is characterized by severe and debilitating
fatigue and includes other symptoms including difficulty concentrating,
myalgia, and nonrefreshing sleep [1 and 2], which cannot be explained by the
presence of well-characterized medical conditions such as cancer. CFS lacks a
known, uniform pathognomic biological marker or pattern of signs; it is a
diagnosis of exclusion based on patient symptom report. Occurrence of CFS in
community samples has been estimated to be about 1% [3 and 4].
Some of the most commonly reported CFS symptoms are problems with cognitive
function. Neuropsychological impairments are subtle in CFS; the best
documented difficulties are in information processing, speed, and efficiency
[5]. Subjective perceptions of cognitive difficulties are greater than
documented impairments; emotional status (e.g., depression) may predict
patients' perceptions of cognitive difficulties, but has not been
well-associated with objective cognitive performance [5]. These associations
warrant further investigation.
Few hypotheses have been postulated to explain the seeming disparity between
subjective reports and objective data in CFS. The purpose of this study is to
examine the role of three related constructs and phenomena, suggestibility,
the nocebo response, and the misinformation effect as potential explanatory
mechanisms for symptom reporting in CFS. Placebo reactions occur in the
absence of known biological causes or effects. The more specific term, nocebo
response, refers to negative reactions to a placebo, such as onset of an
illness after receiving an inert substance or intervention [18]. In the
literature on placebo response, placebos have been demonstrated to modify
both subjectively reported and objectively observed symptoms [6]. For
example, placebos have been shown to cause weakness, palpitations, rashes,
diarrhea, and edema [7], vomiting, tremor, pallor, hives, and changes in
blood pressure [8], as well as anaphylactic reactions [9]. Individual
personality variables and expectations have been associated with placebo
responding. The so-called placebo reactor has been characterized as more
suggestible [10] than the nonreactor.
Suggestibility is defined as the tendency to respond to suggestions.
Synonymous with hypnotizability in the literature, suggestibility is
characterized by response to suggestions and by the perception that the
response behavior is involuntary. For example, during a typical measure of
suggestibility, the Hypnotic Induction Profile (HIP) [11], it is suggested
that the subject's arm will float upward like a balloon. Of course, the
subject raises the arm, but the suggestible person will experience the arm as
floating into the air involuntarily and will report it as such. Dixon et al.
[12] explain this phenomenon in terms of automatic versus strategic
processing. They argue that the highly suggestible individual engages in the
selective and automatic processing of a suggestion that the arm is getting
lighter, i.e., focusing so selectively on the arm to the exclusion of other
stimuli and therefore experiencing it as involuntary. Hilgard and Hilgard
[13] reported, for example, that during hypnotic analgesia, highly
suggestible subjects showed physiological reactions to painful stimuli in the
absence of pain perception. The less-suggestible person, on the other hand,
is more strategically engaging in reality-testing procedures by consciously
attending to and processing the source of the suggestion. Crawford et al.
[14] point out that automatic processing by the suggestible person is due
to increased attentional focus involving disattention to extraneous stimuli
along with a decrease in reality testing.
Response expectancy is the hypothetical explanatory phenomenon in both
placebo effect and hypnotic response [15]; research has shown that
nonvolitional responses can be generated through expectancy of their
occurrence. In these expectancy conditions, alterations of such responses as
nausea, pain perception, sexual arousal, and anxiety, for example, have been
observed and supported by corresponding physiological changes [15].
Expectations of enhanced performance on motor skill tasks due to caffeine
intake was correlated with actual improved performance for a group of college
students receiving no caffeine [16]. In the same study, subjects expecting
caffeine-impaired performance after receiving the placebo actually performed
more poorly than the control group receiving no beverage and no expectation
instructions [16]. Other studies have demonstrated adverse side effects of
medications secondary to expectations of such [17] and patient improvement
following the administration of a homeopathic treatment. There is also a
growing body of evidence connecting placebo responding to onset of illness,
referred to as a nocebo response [18].
Along these same lines, research has shown that suggesting erroneous
information subsequent to an event often results in erroneous reporting about
that event [19]. The research on this `misinformation effect' has indicated
that the erroneous information is incorporated into the subject's memory of
the event. The typical approach of such research has been to have the
subjects experience a stimulus event, often in the form of slides of an
accident or crime scene, then receive false information about the event. On a
recall measure designed to assess the subject's acceptance of the erroneous
information, many subjects in the misinformation condition report the phony
information as having been part of the event. In fact, some studies have
reported differences in reporting accuracy between misinformed and control
subject groups as large as 30% or 40% [20].
Two variables enhance the effects of the false information on recall [20].
Length of the delay between presentation of the event and the presentation of
the misinformation is correlated with the degree of erroneous reporting of
the event: the greater the delay, the greater the likelihood the subject will
accept the false information as accurate. In addition, the degree of subtlety
of the erroneous information also is positively related to the degree of
accepting it as accurate, i.e., the more subtle the presentation, the more
likely it will be incorporated into the subject's recall of the event.
The misinformation effect may be similar to the placebo response,
particularly with regard to physical health concerns. If an individual is
predisposed to being concerned about physical status, s/he may be more
susceptible to suggestions about physiological events, no matter how minor
the event or inaccurate the suggestion. For example, people with panic
disorder appear to have heightened somatic focus. Interoceptive cues such as
a detectable, albeit normal, change in heart rate can trigger a vicious cycle
of fear, leading to further changes in heart rate, that may culminate in a
full blown panic attack. According to Barlow [21], the individual then
rapidly becomes increasingly hypervigilant concerning somatic cues. Such
sensitivity to somatic cues demands much of the individual's attentional
focus as well as serves to precipitate further physiological changes [21].
CFS patients typically focus a great deal of attention on their internal
states [22]. When somatic information, e.g., perceived muscle tenderness, is
consistent with the belief that such sensations result from disease, it is
more readily, or automatically, processed [22]. The misinformation effect [19
and 20] may inadvertently occur during standard medical evaluations of poorly
understood conditions, such as CFS, which lack objective (i.e., biological)
markers. For example, after a delay between the onset of symptoms and the
visit to the doctor's office, the patient is presented with questions about
the specific symptoms that may or may not apply (a potential misinformation
condition). Subsequently, during the course of treatment, the patient is
often asked to recount symptoms of the illness. Repeated recall of the
information (rehearsal) may serve to strengthen the encoding of the
information into long-term memory regardless of the accuracy of the
information.
The placebo response condition may be an appropriate model to understand some
aspects of CFS. Patients with CFS resemble the profile of placebo reactors:
They are concerned about physical symptoms and exhibit vigilance to internal
sensations [22]. Patients with poorly understood physical conditions and a
seemingly unpredictable course, may be more likely to be vigilant than
patients with more consistent, predictable conditions. Further, patients with
CFS complain of concentration and memory difficulties. These two factors may
interact in important ways: First, when a person is unsure of her/his own
ability to recall details of an event, accepting information from another
source, particularly a high status figure [23] such as a physician, may be a
way of compensating for the perceived memory deficits. Second, with increased
attention selectively devoted to monitoring internal states, the patient with
CFS is limited in her/his ability to attend to extraneous stimuli [14] that
may offer alternative explanations for changing internal states. Third, there
is ample evidence that patients with CFS have difficulties processing complex
cognitive information [5], a characteristic consistent with research on
hypnotizability and the selective attentional focusing of highly hypnotizable
subjects [14 and 24].
The present study, then, will examine the associations between suggestibility
and cognitive functioning among patients with CFS, as compared with healthy
patients. The hypotheses are that (1) patients with CFS will show more
suggestibility than healthy persons; (2) patients with CFS will perform more
poorly on neuropsychological measures that require inhibition of automatic
processing but will not perform differently from healthy persons on memory
tasks. Research has shown that, in general, memory per se is not affected in
CFS [5], therefore, we predict that the groups will be similar in terms of
overall memory functioning. Previous research has shown the Stroop test to be
a reliable measure of the automatic processing associated with suggestibility
[12], and we predict that the CFS group will perform more poorly on the
Stroop than the healthy controls; (3) automatic processing will be positively
related to suggestibility for patients with CFS as compared to healthy
persons; and (4) greater suggestibility will be associated with more numerous
and severe psychological symptoms.
Methods
PARTICIPANTS
Twenty-one patients with CFS were recruited from the outpatient CFS clinic at
the National Jewish Medical and Research Center (NJMRC). Selection of the
participants began with a standardized review of medical records of CFS
clinic patients for those meeting the 1988 case definition of CFS [1]:
Utilizing a checklist of CFS symptoms, records were examined for evidence of
major CFS symptoms, at least 8 of 11 minor symptoms, and absence of any
exclusionary diagnoses. Participants were administered the Diagnostic
Interview Schedule for DSM-IIIR [25] to screen for psychiatric diagnoses that
would exclude them from consideration of CFS as a diagnosis. The exclusions
included any current or preexisting Axis I diagnosis. All participants also
met the 1994 case definition of CFS [2]. The 1988 CFS case definition was
applied because it is more conservative in terms of psychiatric exclusions,
which would lead to increased homogeneity within and between the groups of
subjects, thereby also reducing the likelihood that any group differences in
the dependent variables would be attributable to or confounded by group
differences in psychopathology.
Twenty-one healthy control subjects were also recruited from hospital
research and nursing staff and screened in a similar manner. Healthy controls
had no current or recent history of medical illnesses, including a history of
CFS symptoms. Healthy controls were also administered the Diagnostic
Interview Schedule for DSM-IIIR [25] to screen for psychiatric diagnoses, and
excluded on the basis of any Axis I diagnosis.
Measures
Participants completed two suggestibility measures, three tests of cognitive
functions and a global measure of psychological symptoms. The measures of
cognitive function were used to characterize premorbid intellectual function
and assess current cognitive functioning.
SUGGESTIBILITY TASK
The suggestibility task was patterned after studies designed by Loftus et al.
[19 and 26]. Participants were read a neutral story that was presented as a
standard story memory test. After hearing the story, subjects were given a
questionnaire purportedly measuring their recall of the story (Recall I). The
questionnaire actually contained false information about the story embedded
in the questions. The false information was divided into half health-related
and half non-health-related items. After a delay, during which several of the
other measures were administered, subjects were given a recall measure
(Recall II) that consisted of forced-choice questions (real vs. false items)
to measure to what extent they incorporated the false information into their
reports of events depicted in the neutral story. There were eight total
misinformation items (four health-related and four non-health-related items),
so the participants' misinformation scores ranged from 0 to 8 for the total
score, and 0 to 4 for the health- and non-health-related scores.
HYPNOTIC INDUCTION PROFILE (HIP) [11]
The HIP is a brief structured technique that measures behavioral, perceptual,
and cognitive responses to suggestions. Briefly, subjects are asked to
perform an eye roll and then once their eyelids are closed, the hypnotic
induction is begun in the form of an imagery technique guided by the
examiner. The induction involves suggestions of floating and arm levitation.
Postinduction ratings include subjects' reports of physical sensations,
perceptions of dissociation, and involuntariness of actions. An induction
score is obtained based on the number of reinforcers required for arm
levitation, the arm levitation, reported experience of dissociation and
floating, amnesia to the cut-off signal, all of which contribute to an
overall experience of involuntariness of actions. Induction scores range from
0 to 12. An eye roll score is also obtained, the eye roll being a relatively
stable indicator of suggestibility [11]. Briefly, the participant is
instructed to gaze upward as far as possible while holding the head in a
horizontal position. The participant is then instructed to slowly close the
eyelids while holding the upward gaze. Eye roll scores are calculated by
measuring the amount of sclera visible between the lower edge of the iris and
the lower eyelid and by measuring the amount of squint that occurs while
closing the eyelid. Eye roll scores range from 0 to 7. Both the induction
score and eye roll score are indicators of suggestibility, i.e., the higher
the score, the greater the level of suggestibility.
STROOP NEUROPSYCHOLOGICAL SCREENING TEST [27]
This test assesses the ability to shift perceptual sets to conform to
changing demands, suppressing an automatic response while producing a
controlled response, and completing the task while distracted. This test
involves two identical stimulus sheets, which consist of 112 color names
arranged in columns, and printed in one of four colors. No word is printed in
its matching color. For the first trial, subjects are timed while reading
aloud the printed words. For the second trial, subjects are timed while
naming the color of ink in which the word is printed, and not reading the
word. The Stroop yields two scores: a raw score and a percentile rank for
same-aged peers. Research using the Stroop test has also been used to
differentiate between low-hypnotizable and high-hypnotizable subjects. Highly
hypnotizable subjects show a significantly greater automaticity of processing
information [12 and 24].
NORTH AMERICAN ADULT READING TEST (NAART) [28]
This test was given to assess intellectual functioning and yields a
full-scale IQ score. The test consists of 61 irregularly spelled words
printed in two columns on both sides of an 8.5-11 in. card, which is given to
the subject to read. Blair and Spreen [28] reported that the correlation
between the WAIS-R FSIQ and NAART-predicted FSIQ is .75.
WECHSLER MEMORY SCALE-REVISED (WMS-R); LOGICAL MEMORY SUBTEST (IMMEDIATE RECALL
ONLY) [30]
Research using the WMS-R has shown it to be sensitive to memory disturbances
in a number of patient groups [29] and thus is a useful screening tool. The
Logical Memory Subtest assesses the ability to recall ideas in two orally
presented stories and has extensive scoring instructions that result in few
scoring ambiguities [30]. The first story of this subtest of the WMS-R was
used as a screen for memory difficulties to control for gross between-group
differences in memory function.
BRIEF SYMPTOM INVENTORY [31]
This is a 53-item self-report measure of emotional, somatic, perceptual, and
cognitive symptoms with well-established psychometric characteristics. For
purposes of this study, two summary scores were used: the Positive Symptom
Index (PSI), a measure of the number of symptoms reported, and the General
Severity Index (GSI), which measures the depth of distress experienced.
Procedures
After being selected according to CFS case definition criteria, each person
was contacted by the investigator and asked to participate in the study after
the procedures were described. Those who agreed were then scheduled to come
into the laboratory. Each subject took about 1 hour to complete the tests.
All participants were tested in the afternoon. Procedural steps were as
follows:
1. Subjects reported to NJMRC and were given the informed consent form to
read and sign; the forms explained the nature of the study with the
exception of the suggestibility manipulation.
2. Subjects were then administered the following:
(a) Suggestibility (misinformation) story;
(c) Stroop test;
(d) NAART;
(e) Brief Symptom Inventory;
(f) HIP;
(g) Suggestibility Recall II; and
(h) WMS-R, Logical Memory Subtest (Immediate Recall Only).
3. At the conclusion of their participation, subjects were debriefed in both
written and verbal form. The debriefing provided full disclosure of
the purpose of the study and included an explanation of the deception
involved.
4. Subjects were paid for their participation.
Statistics
Descriptive statistics were used to describe the demographic characteristics
of the groups. t tests were used to test for group differences in demographic
variables (age and years of education). If homogeneity of variance
assumptions were not met, the results based on unequal variance t values were
reported. One-way analyses of covariance were used to test for group
differences on the measures of suggestibility and cognition, controlling for
any demographic variables that differed by group. Finally, correlations were
calculated between the suggestibility measures and measure of automatic
processing (Stroop test) and psychological symptoms.
Results
SAMPLE CHARACTERISTICS
The CFS group (n=21) consisted of 3 male and 18 female subjects. Of the 21
CFS patients, one was of Hispanic origin, the remaining were white, not of
Hispanic origin. The ethnic and gender composition of this subject group
approximated that of the larger population of CFS patients seen at NJMRC.
Mean age of the CFS group was 40.19 (S.D.=7.2). Mean years of education of
the CFS group was 14.48 (S.D.=2.04).
The healthy control group (n=21) was recruited from hospital nursing and
research staff and consisted of 4 male and 17 female subjects, all of whom
were white, not of Hispanic origin. Mean age of the control group was 33.85
(S.D.=6.7). Mean years of education of the healthy control group was 15.52
(S.D.=2.67).
The healthy control group was significantly younger than the CFS group
[t(40)=2.95, P<.01]1. Therefore, age was used as a covariate in all
subsequent group comparisons. The between-groups difference in years of
education was nonsignificant [t(40)=-1.42, ns].
GROUP COMPARISONS ON SUGGESTIBILITY
It was predicted that CFS patients would demonstrate greater suggestibility.
As shown in Table 1, patients with CFS had significantly higher eye roll
scores than the healthy controls [F(1,39)=36.56, P<.001], after controlling
for age. In addition, the CFS group's mean eye roll score was notably greater
than the expected mean eye roll score of 2.4 for highly hypnotizable persons
reported by Spiegel and Spiegel [11]. The induction scores followed a similar
pattern, showing significantly higher [F(1,39)=37.57, P<.001] average
induction scores for the CFS group than for the control group. Thus, the
participants with CFS showed significantly greater suggestibility on a global
measure of suggestibility than the healthy control group.
For the misinformation task, between-groups differences in total number of
errors and nonsomatic errors were nonsignificant. Inspection of the data in
Table 1 suggests that subjects with CFS were more likely to accept
somatically related misinformation than healthy control subjects, but this
effect could not be tested statistically because of the lack of variability
among the scores for the latter subjects.
GROUP COMPARISONS ON COGNITIVE TESTS
CFS patients and healthy controls did not differ significantly on either the
WMS-R logical memory immediate recall or the NAART estimated FSIQ. Thus, the
two groups were equivalent in terms of both intellectual functioning and
memory. There was a significant between-groups difference in which the CFS
group performed more poorly than the healthy controls on a measure of
automatic processing, the Stroop test [27] [F(1,39)=7.03, P<.05], after
controlling for age. In addition, the CFS group's mean raw score of 96 fell
below the impairment cutoff of 98, placing them in the impaired range of
functioning. These data are presented in Table 2.
ASSOCIATIONS OF SUGGESTIBILITY WITH AUTOMATIC PROCESSING AND PSYCHOLOGICAL
SYMPTOMS
Automatic processing was significantly related to scores on suggestibility
measures. For the entire sample, induction scores were negatively correlated
with both Stroop raw scores (r=-.40; P<.05) and with Stroop percentile scores
(r=-.26; P<.05), such that the level of performance on the Stroop decreased
as induction scores increased. Correlations between eye roll scores and
Stroop scores were nonsignificant. Stroop raw scores were negatively
correlated with somatic errors (r=-.62; P<.01), such that impaired
performance on the Stroop was associated with greater numbers of somatic
errors on the misinformation task. Correlations between errors and Stroop
percentiles were not significant. Eye roll scores were positively correlated
with number of somatic errors on the misinformation task (r=.30; P<.05), such
that the greater the eye roll score, the greater the number of somatic
errors. These results lend support to the assertion that greater
suggestibility is related to the inability to inhibit automatic processing of
information.
Both general and specific measures of suggestibility were related to the
number and severity of psychological symptoms. As shown in Table 3, the eye
roll score was positively correlated with the number and severity of symptoms
endorsed (both PSI and GSI) of the Brief Symptom Inventory. Induction score
was positively correlated with both the PSI and the GSI of the Brief Symptom
Inventory. In addition, somatic errors from the misinformation task were
positively correlated with the number of symptoms.
Discussion
The data supported the first hypothesis that the participants with CFS were
more suggestible than healthy persons on a measure of general suggestibility,
the HIP [11]. Support for the more specific misinformation effect was mixed.
The CFS group made more somatic errors than the control group, the controls
having made no somatic errors. Group differences in both nonsomatic errors
and total errors were nonsignificant. It is possible that the methodology
used in the present study attenuated the robustness of the misinformation
task. Loftus [20] points to elapsed time between the presentation of the
event and presentation of the misinformation as an important variable in the
acceptance of the false information. In the present study, the elapsed time
between presentation of the story and presentation of the false information
was minimal, thus possibly interfering with the misinformation effect.
There were no differences between participants with CFS and healthy controls
on both the global screen of memory functioning and the measure of
intellectual functioning. While the primary purpose of the study was to
investigate suggestibility, not neuropsychological performance per se, our
results are consistent with past research that CFS patients typically
demonstrate intact functioning on these measures [5] but have difficulties
with other tasks, including speed-dependent information processing (e.g.,
[32]) and verbal memory involving list learning [33]. However, on the
measure of automatic processing, the Stroop test, the CFS group performed
significantly more poorly than the control group and fell in the impaired
range of performance for same-aged peers. This measure is a timed task and as
patients with CFS have difficulties with speed-dependent information
processing, a goal for future research would be to untangle the relative
contributions of speed-dependent processing and automatic processing from
these patients' performance difficulties. In summary, these results supported
our second hypothesis that subjects with CFS performed more poorly on a
specific measure of automatic processing than control subjects, but the
groups did not differ on global measures of intellectual or memory function.
In addition, consistent with our third hypothesis, subject performance on the
Stroop was significantly negatively associated with a measure of global
suggestibility, the induction score of the HIP. That is, the inability to
inhibit automatic processing was associated with greater suggestibility.
Finally, suggestibility was also associated with increased numbers and
severity of psychological symptoms, as had been posited as the fourth
hypothesis. These results of the associations among suggestibility, automatic
processing, and psychological symptoms, while statistically significant, left
the majority of the variance in suggestibility unaccounted for by these other
factors. Future research should examine further the role of suggestibility as
a potentially relevant information processing style among persons with
medically unexplained illnesses such as CFS.
Results of this preliminary investigation appear to offer support for the
role of suggestibility among some persons with CFS. The nocebo effect, or the
onset of an illness after an inert intervention, may occur among some persons
with CFS, although this speculation awaits examination using longitudinal
data in future studies. Placebo responding has long been well documented in
the literature, particularly with regard to the effects and side effects of
medications or medical treatments. However, less is understood regarding the
onset or maintenance of illness as the result of placebo response. The
participants with CFS in the present study did demonstrate the selective and
automatic processing of the suggestions during administration of the HIP,
findings also supported by results from the Stroop test. The subjects could
not inhibit their automatic processing in the face of the distracting or
inaccurate information with the Stroop or the HIP, respectively. Stated
alternatively, patients with CFS have relative difficulties attending to
relevant, if peripheral, information. This effect could, in turn, be
subjectively experienced as memory or cognitive deficits.
It is important to emphasize here that suggestibility is not synonymous with
gullibility as some might infer. Rather, suggestibility refers to a type of
information processing that is selective and distorted in that relevant
information cannot be attended to and incorporated in a balanced fashion.
Suggestible persons with CFS are certainly experiencing the symptoms they
report. However, a tendency to focus on symptoms, perhaps to the exclusion of
other information, may be related to CFS patients' difficulties in processing
complex cognitive information, and difficulties with divided attention [33].
The methodological issues in the current study, e.g., sample size, lack of
delay between presentation of the misinformation story and the false
information, use of an analogue laboratory task rather than a more
naturalistic examination, etc., demand that these data be interpreted with
caution. However, these results do suggest directions for future research, in
addition to those mentioned above. The inclusion and comparison of additional
groups with qualities that are hypothetically shared with or distinct from
CFS would be an extremely interesting direction for future research, as would
be the examination of the longitudinal relationship between suggestibility
and illness. The study of suggestibility among patients with CFS as compared
to other medically unexplained illnesses or illnesses with a relapsing and
remitting course may help elucidate the possible mechanisms underlying our
observed associations of suggestibility among persons with CFS: For example,
does uncertainty regarding the cause or the course of the illness increase
suggestibility, or does suggestibility increase the likelihood of medically
unexplained illness? To the extent that suggestibility and automatic
processing characterize CFS, treatment of CFS symptoms may be enhanced by
cognitive rehabilitation that includes practicing divided attention and
focused attention tasks, cognitive reframing strategies (e.g., to suggest
alternate, benign interpretations for somatic sensations, such as feeling
tired after walking being a sign of deconditioning, rather than of further
injury), and/or hypnosis, to refocus the patients' attention to the
nonsomatic realm, or employ suggestions for enhanced functioning.
Acknowledgements
This study was supported in part by a grant from the National Institute of
Allergy and Infectious Diseases, U01-AI32244. The authors would like to thank
C. Munro Cullum, PhD, for his assistance in the development of this study.

Tables
Table 1. Group differences on measures of suggestibility
----------------------------------------------------------------------
Hypnotic induction profile Misinformation task
Eye roll* Induction* Somatic Nonsomatic
M S.D. M S.D. M S.D. M S.D.
----------------------------------------------------------------------
CFS 3.43 0.75 9.10 2.73 0.19 0.51 0.38 0.58
Controls 1.33 1.11 2.33 3.17 0.00 0.00 0.52 0.68
----------------------------------------------------------------------
* P<.001.

Table 2. Group differences in global memory, intellectual functioning,
and automatic processing
----------------------------------------------------------------------
WMS memory FSIQ Stroop raw *
M S.D. M S.D. M S.D.
----------------------------------------------------------------------
CFS 12.81 3.19 107.91 7.77 96.15 17.75
Controls 14.71 3.36 112.52 6.91 106.95 8.86
----------------------------------------------------------------------
* P<.05.

Table 3. Correlations between the measures of suggestibility and
psychological symptoms
----------------------------------------------------------------------
GSI PSI
Hypnotizability
Eye roll .409* .597*
Induction .475* .405*
Misinformation task
Somatic errors .160 .524*
Nonsomatic errors ^B .085 .004
----------------------------------------------------------------------
* P<.01.

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