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PAMELA SADLER AND ERIK Z. WOODY
Kirsch, 1999); and K. Bowers and Woody (1996) showed that the
traditional, low-effort approach to hypnotic amnesia was more effec-
tive than deliberately trying to suppress the proscribed thought (see
also K. Bowers & Davidson, 1991; Davidson & Bowers, 1991). A third
strategy is to manipulate cognitive load, which reduces the available
cognitive resources, and to examine the effect on hypnotic responding.
For example, Eastwood, Gaskovski, and Bowers (1998) showed that
hypnotic analgesia was less impaired by cognitive load than was a
stress inoculation procedure; likewise, King and Council (1998)
showed that hypnotic amnesia was relatively unaffected by cognitive
load, unlike deliberate thought suppression.
Another approach, not so reliant on special experimental manipula-
tions, is to try to devise an index of cognitive effort during hypnosis.
One seemingly straightforward possibility is to use participants
’
sub-
jective ratings of effort (e.g., Green, Page, Handley, & Rasekhy, 2005);
however, this index is problematic because both the dissociated-
experience and social-cognitive theories of hypnosis specifically posit
that subjective effort is an inaccurate and misleading index of actual
cognitive effort. Ruehle and Zamansksy (1997; see also Zamanasky &
Ruehle, 1995) provided an intriguing initial exploration of some possi-
ble alternative indices of cognitive effort. In two studies in which par-
ticipants worked on addition problems, the indices of cognitive effort
were subjective estimates of elapsed time (lower estimates imply
greater cognitive effort) and actual time to complete problems (more
time implies greater cognitive effort). In response to the hypnotic sug-
gestion to forget one number (e.g., 8) and replace it with another (e.g.,
9), high hypnotizable participants completed problems involving those
numbers with no increase in cognitive effort compared to normal
problems, unlike simulators. In the present research, we attempt to
build on this idea of measuring cognitive effort in ways that get
around the subjective self-report of effort.
In summary, to discriminate among theories of hypnosis, subjective
reports of effort are not sufficient, because all three theoretical perspec-
tives predict that high hypnotizable participants experience their
responses to hypnotic suggestions as effortless. In contrast, the theories
make different predictions about the actual underlying level of cognitive
effort. The dissociated-experience and social-cognitive theories predict
that high hypnotizables exert relatively high actual effort; whereas the
dissociated-control theory predicts that they exert relatively low actual
effort. Therefore, to discriminate among these theories, what is very use-
ful is a way of measuring actual, underlying effort.
Heart-Rate Change as an Indicator of Cognitive Effort
One way to measure such underlying effort is to monitor heart rate.
Lacey and colleagues (Lacey, Kagan, Lacey, & Moss, 1963; Lacey &
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