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ROLE OF COGNITIVE EFFORT
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is possible that the way hypnotic suggestions are worded has an
important effect on the effortless experiencing of hypnotic imagery
and perhaps on actual expended cognitive effort as well. Lynn, Rhue,
and Weekes (1990) emphasized that “suggestion wording and struc-
ture are important determinants of involuntariness” (p. 175), because
they convey implicit and explicit messages to participants about how
to experience hypnotic suggestions. In two earlier studies of heart rate
and imagery in hypnosis (Hughes, 1988; Rothmar, 1986), there were
indications that differences between highs and lows may possibly be
affected by the wording of imagery suggestions. Therefore, in the
present study a manipulation of the wording of the imagery sugges-
tions was planned such that each participant received effortless sug-
gestions for some imagery trials (“let the image occur spontaneously,
just like watching a movie”), and more effortful suggestions for other
imagery trials (“make the scene happen through your own will and
effort, maintaining control of the image”).
Predictions According to the Different Theories
The central issue in this research is whether the richer imagery expe-
rience of high hypnotizable participants is a result of their expending a
higher level of underlying cognitive effort than their low hypnotizable
counterparts. Therefore, it is necessary first to verify that the subjective
experiences of high hypnotizable participants are different from those
of lows, which leads to our first prediction:
1. Consistent with previous research on imagery vividness, absorption,
and effort (P. Bowers, 1978, 1982; Hughes, 1988; Rothmar, 1986), we
expected that high hypnotizable participants would experience their
imagery as more vivid, more absorbing, and less effortful than lows.
Next, suggestion wording may also affect some aspects of the
subjective experience of imagery. However, we did not expect sug-
gestion wording would interact with hypnotizability, because the
response differences between highs and lows should not depend on
details of suggestion wording. This reasoning leads to our second
prediction:
2. Consistent with the arguments advanced by Lynn, Rhue, and Weekes
(1990), we expected that, compared to the effortless wording, the effort-
ful suggestion wording would increase self-perceived effort and self-
perceived control concerning the imagery.
Turning to underlying cognitive effort, as indexed by heart-rate
increase, the alternative theories of hypnosis make sharply competing
predictions:
3a. The social-cognitive (e.g., Spanos, 1986) and dissociated-experience
theories (e.g., Kihlstrom, 1985) imply that high hypnotizable participants
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