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factor associated with this change was the observation that higher
avoidance responses at the follow-up assessment were associated with
increases in SHCS scores. Several explanations may be offered for this
finding. First, avoidance symptoms of PTSD include dissociative-type
responses, such as withdrawal, emotional numbing, and amnesia. It is
possible that participants with elevated dissociative-type responses to
the trauma were more prone to responding to hypnosis because of their
aptitude for dissociative tasks. This view is consistent with proposi-
tions that dissociative clinical disorders display higher levels of hyp-
notizability because of their aptitude for dissociation (Butler et al., 1996;
Kihlstrom et al., 1994). The strong association between increased
hypnotizability and elevated avoidance scores may be explained by
the particular characteristics of avoidance in PTSD. Amajor component
of avoidance symptoms in PTSD involves withdrawal from one’s
environment (Foa, Riggs, & Gershuny, 1995). One possibility is that
this withdrawal is associated with more absorption in subjective
experiences, which is strongly correlated with hypnotizability (Roche
& McConkey, 1990). This interpretation is consistent with some evi-
dence that hypnotizability scores have been shown to increase follow-
ing brief isolation in the Antarctic (Barabasz, Barabasz, & Mullin, 1983)
and in a restricted environmental stimulation chamber (Barabasz, 1982;
Barabasz & Barabasz, 1989). We recognize, however, that hypnotiz-
ability comprises a range of constructs, including dissociation, sug-
gestibility, and absorption (Glisky, Tataryn, Tobias, Kihlstrom, &
McConkey, 1991). Future prospective studies of posttraumatic adjust-
ment should investigate constructs associated with hypnotizability to
determine the specific features of hypnotizability associated with
posttraumatic psychopathology.
The observed findings may also be explained by a more socio-
cognitive perspective (Council, Kirsch, & Hafner, 1986). It is possible
that a proportion of participants perceived questions about dissociative
aspects of PTSD in a way that cued them to respond positively to the
hypnotic testing. This perspective accords with claims that the suggest-
ible nature of highly hypnotizable individuals makes them more prone
to endorsing questions about dissociative experiences, because they are
strongly influenced by the cued questions (Bowers, 1991). This possi-
bility is heightened by the procedure in which psychopathology scores
and hypnotizabilitywere administered in the same context at the follow-
up assessment. Further, although the clinicians who administered the
SHCS at the follow-upwere not aware of the participants’ psychopathol-
ogy scores at the time of the SHCS administration, it is possible that the
clinicians were not fully blind to participants’ diagnostic status, and this
may have influenced their administration of the SHCS.
Inferences from this study are limited by the possibility that therapy
may have influenced responding on the SHCS. Future studies should
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