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Intl. Journal of Clinical and Experimental Hypnosis, Vol. 54, No. 4, July 2006: pp. 1–37
I
DOES THE MORE VIVID IMAGERY OF
HIGH HYPNOTIZABLES DEPEND ON
GREATER COGNITIVE EFFORT?
A Test of Dissociation and Social-Cognitive
Theories of Hypnosis
Role of Cognitive Effort
PAMELA SADLER AND ERIK Z. WOODY
P
AMELA
S
ADLER
1,2
Wilfrid Laurier University, Waterloo, Ontario, Canada
E
RIK
Z. W
OODY
University of Waterloo, Ontario, Canada
Abstract:
In an investigation of the role of cognitive effort in hypnotic
responding, high and low hypnotizable participants produced emo-
tionally neutral imagery in response to effortful versus effortless hyp-
notic suggestions. Heart-rate increase served as an objective index of
cognitive effort, and subjective ratings of imagery vividness, absorp-
tion, effort, and control were collected. Compared to lows, high hyp-
notizable participants experienced their imagery as more vivid and
absorbing, yet their heart rates indicated no higher level of cognitive
effort than lows. Compared to effortless wording, effortful wording
of suggestions increased cognitive effort in lows, as indexed by heart-
rate increase, but had no effect on the effort expended by highs.
Ratings of subjective control were strongly correlated with subjective
effort for lows but unrelated for highs. These results support the
dissociated-control theory of hypnosis rather than the dissociated-
experience or social-cognitive theories.
What is the role of cognitive effort in hypnotic responding? Major
theories of hypnosis all recognize the importance of the experience of
effortlessness in hypnotic responding, but they propose very different
underlying mechanisms for it (Woody & Sadler, 1998, in press).
Proponents of the dissociated-experience theory (e.g., Kihlstrom,
1985) argue that high hypnotizable participants actually execute hyp-
notic responses effortfully, but this effort is dissociated or blocked
Manuscript submitted November 26, 2005; final revision received March 31, 2006.
1
Preparation of this article was supported by grants from the Social Sciences and
Humanities Research Council of Canada to the first author and from the Natural
Sciences and Engineering Research Council of Canada to the second author.
2
Address correspondence to Pamela Sadler, Department of Psychology, Wilfrid
Laurier University, 75 University Avenue West, Waterloo, Ontario, Canada N2L 3C5.
E-mail: psadler@wlu.ca
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