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PAMELA SADLER AND ERIK Z. WOODY
are actually expending greater cognitive effort than lows, even though
they are not aware of it. Thus, the prediction is a main effect of hypnotiz-
ability, with highs showing greater heart-rate increases during imagery
than lows.
Because, according to these theories, high hypnotizable participants
spontaneously recruit cognitively effortful strategies more readily than
lows, this difference should show up just as well in the effortless-
wording condition as in the effortful-wording condition. Thus, the
main effect of hypnotizability should not be qualified by suggestion
wording.
According to dissociated-control theory (K. Bowers, 1992), the
greater responsiveness of high hypnotizable participants is not due to
greater actual cognitive effort. Thus, this theory implies, in contrast to
the previous two theories, that highs will generally not show greater
heart-rate increases than lows, even though their experience of imag-
ery is more subjectively compelling. Further, we predicted an interac-
tion of hypnotizability with suggestion wording:
3b. Dissociated-control theory (e.g., Miller & Bowers, 1993) implies that
although the responsiveness of low hypnotizable participants may be
related to underlying cognitive effort, the responsiveness of high hypnotiz-
able participants is not. Thus, the prediction is that for lows the effortful-
wording condition will lead to greater heart-rate change than the effortless-
wording condition, whereas this difference will be absent for highs.
In essence, the effortful wording of imagery suggestions should
encourage effort in the lows that the highs do not require.
M
ETHOD
Participants
Twenty-five high hypnotizables (13 men and 12 women) and 23 low
hypnotizables (12 men and 11 women) were chosen for participation in
this study based on their scores on the Harvard Group and Waterloo
Group C scales (HGSHS:A; Shor & Orne, 1962; WSGC; K. Bowers,
1993). Highs had scored nine or above on both hypnosis scales, and
lows scored four or below on both scales.
Apparatus
A Polar Vantage XL telemetry heart-rate monitor was used to mea-
sure heart rates. Each participant wore a chest band with electrode
transmitters positioned on the lower right and left rib cages. A small
radio receiver, which was placed on a table between the participant
and the experimenter, stored the participant’s heart rate every 5 sec-
onds. After the experiment was completed, the heart-rate data were
downloaded from the receiver to a computer for analysis.
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