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MacDonald and colleagues (2000) report an fMRI study of a
Stroop task using a task-switching methodology between presignaled
color-namingandword-naming. Thismethodologyhasmuch incommon
with that adopted in this paper. The lDLPFCwas more active during task
preparationwhereas the ACCwasmore active during stimulus presenta-
tion. They argue that a system of cognitive regulation (i.e., the SAS)
requires one element to implement control and another to monitor
performance and provide feedback to adjust control. They propose a
divisionwithin anterior executive functioningwith the anterior cingulate
responsible for monitoring functions and the lDLPFC actually imple-
menting control. This interpretation applied to the present results would
imply that it is not the total SAS or anterior cortex that is functionally
dissociated in hypnosis but rather the lDLPFC.
The difficulty level of the Stroop paradigm adopted here in
conjunction with the power of the study is likely to have played
a key role in obtaining a significant hypnosis by susceptibility
interaction effect for total Stroop errors. However, the slowing of
high response conflict color-naming in hypnosis was also matched
by a slowing in the much lower response conflict word-naming of
the color and word-incongruent stimuli used in this study. The
difference in reaction time between high and low response-conflict
trials appears not to have diminished in hypnosis whereas overall
reaction time has. It appears then that the actual process of response
selection may not have changed in hypnosis; rather what has
changed is the efficiency of the control of that process. The specific
modification of dissociated-control theory being proposed therefore
is that during hypnosis the control functions of the lDLPFC become
functionally dissociated from the monitoring feedback of the ACC
(which remains unimpaired) and from the processes over which they
normally exert control.
R
EFERENCES
Banich, M. T., Milham, M. P., Atchley, R. A., Cohen, N. J., Webb, A., et al. (2000).
Prefrontal regions play a predominant role in imposing an attentional ‘‘set’’:
Evidence from fMRI.
Cognitive Brain Research
,
10
, 1–9.
Botvinick, M., Nystrom, L. E., Fissell, K., Carter, C. S., & Cohen, J. D. (1999). Conflict
monitoring versus selection-for-action in anterior cingulate cortex.
Nature
,
402
,
179–181.
Dixon, M., Brunet, A., & Laurence, J.-R. (1990). Hypnotizability and automaticity:
Toward a parallel distributed processing model of hypnotic responding.
Journal of
Abnormal Psychology
,
99
, 336–343.
Donovan, P. B. (1989). Task explication of trait (absorption) differences in performance
using Stroop interference. Unpublished doctoral thesis, University of Queensland,
Australia.
Jack, A. I., & Shallice, T. (2001). Introspective physicalism as an approach to the science
of consciousness.
Cognition
,
79
, 161–196.
246
GRAHAM A. JAMIESON
AND
PETER W. SHEEHAN
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