Basic HTML Version
ROLE OF COGNITIVE EFFORT
385
address a different issue from between-group phenomena (such as the
distinction between highs and lows), they reinforce the potential
importance of nonsubjective measures of cognitive effort.
D
ISCUSSION
The main purpose of the present study was to provide a further
evaluation of major theoretical perspectives on hypnosis (see Woody &
Sadler, 1998, for a review). Replicating previous research on imagery
in hypnosis (P. Bowers, 1978, 1982; Hughes, 1988; Rothmar, 1986), we
found that high hypnotizable participants experienced their imagery
as more vivid and absorbing, and less effortful, compared to their low
hypnotizable counterparts. The dissociated-experience and social-cog-
nitive theories of hypnosis imply that this richer imagery experience of
high hypnotizables should be the result of expending a higher level of
cognitive effort than lows. However, using heart-rate increase as an
index of cognitive effort, we found no indication of greater cognitive
effort on the part of the high hypnotizables. Instead, we obtained a
predicted interaction of hypnotizability with suggestion wording,
derived from the dissociated-control theory of hypnosis. As expected,
effortful suggestion wording led to increased cognitive effort by low
hypnotizable participants but had no effect on the cognitive effort
exerted by highs. This pattern is consistent with the idea that effortful
wording encourages cognitive effort in the lows that is not relevant for
the highs. According to dissociated-control theory, effortful suggestion
wording is largely irrelevant for highs because their mode of enacting
suggestions bypasses cognitive effort, rather than requiring it.
The pattern of within-group correlations among subjective mea-
sures was also consistent with dissociated-control theory. Whereas
subjective control was strongly positively correlated with subjective
effort for low hypnotizable participants, it was uncorrelated with sub-
jective effort for highs. In addition, the relations of subjective control to
imagery vividness and absorption were distinct for lows versus highs,
supporting the idea that differences in underlying control processes
are central to the difference between lows and highs.
Another aim of the present study was to advance a nonself-report
index of cognitive effort during hypnosis. The concerns by some hypno-
sis theorists that subjective report of effort may be an inaccurate and
misleading index of actual cognitive effort was confirmed by the consis-
tent lack of relation between self-reported effort and heart-rate increase,
our objective measure of cognitive effort. We believe that future research
contrasting major theories of hypnosis would benefit from the inclusion
of nonself-report indices of cognitive effort rather than relying only on
participants’ ratings of subjective effort (e.g., Green et al., 2005; see Woody
& Sadler, 2005). It may be possible to develop other nonself-report
Downloaded by [University of Macedonia] at 02:14 29 March 2012