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strategies was addressed through the inclusion of ‘‘no-strategy’’ and
‘‘rehearsal’’ instruction conditions. An additional no-instruction con-
trol condition was added for comparison. The strategy and effort
manipulations did not significantly affect any of the objective Stroop
performance measures. Although hypnosis may well induce relaxation
(depending on the induction procedure) and does lead to a significant
reduction in the use of rehearsal and positional preparatory strategies,
there is no evidence in this study that direct instructions to manipulate
strategy use or effort lead to effects comparable to hypnosis.
There is a significant effect for hypnosis on each of the strategies
examined in this study. Rehearsal use decreases significantly in hyp-
nosis along with positional strategy use, whereas experiential strategy
use increases in hypnosis (see Table 3). Conversely, the nonhypnotic
condition is associated with rehearsal and positional strategy use but
not experiential strategy use. Active preparation to respond to antici-
pated events, as occurs in both rehearsal and positional strategies,
seems characteristic of nonhypnotized task performance. Active mental
preparation appears to be diminished in the hypnotized condition. This
is consistent with Tellegen’s (1981) concept of an instrumental set that
some individuals can put aside in appropriate circumstances, such as
hypnosis.
The use of the rehearsal strategy was significantly lower in high than
low susceptibles and significantly lower in the hypnotized than the
nonhypnotized condition. Table 4 shows that mean rehearsal use is
lowest among hypnotized highs. What is surprising about rehearsal
use is that it is not significantly affected by instructional condition.
Rehearsal is, however, significantly reduced by hypnosis, indicating
that hypnosis may be linked to a process not readily susceptible to
voluntary manipulation.
In this study, a significant interaction was found for experiential set
between hypnosis and susceptibility. Looking at Table 5, it is evident
that the experiential set is occurring primarily in the hypnotized high
susceptible condition. The experiential set response is not a sponta-
neous preference of either highs or lows when performing this task in
the nonhypnotized condition. Rather, it emerges among highs in
hypnosis, as part of their response to the hypnosis condition.
The experiential set is highest (in hypnosis) when rehearsal and
positional responses are lowest (see Table 3). The experiential set, then,
is associated with the diminished use of active (instrumental) strategies
just as it was presumed to be. However, the set was not significantly
increased by either no-strategy or relaxation instructions. Just as the
experiential set is not defined for the trait ‘‘absorption’’ purely by the
absence of an instrumental set (Tellegen, 1981), so the experiential set
measured in hypnosis seems to reflect more than the absence of
instrumental task strategies.
244
GRAHAM A. JAMIESON
AND
PETER W. SHEEHAN
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