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Abstract:
Abstract: Impairments of set-shifting have been associated
with damage to both the basal ganglia and frontal lobes. Previous
research with these groups has used tasks that require the ability
to think strategically - a faculty that may be differentially
affected by frontal lobe pathology - as well as the ability to
shift set (e.g., Wisconsin Cart Sorting Test). Given that shifting
costs normally increase as tasks become more cognitively taxing, it
is unclear whether frontal patients' apparent shifting impairments
are due to shifting problems per se or because they are less
efficient problem- solvers. In two experiments, we attempted to
dissociate the performance of frontal and Parkinson patients on a
shifting task that varied in the degree of problem-solving
difficulty through the manipulation of a cue word. All subjects
displayed lower shifting costs when given a cue but frontal
patients shifting cost remained higher than controls despite a
reduction in task difficulty. In contrast to the other two groups,
frontal patients were not generally faster when a cue was present.
We hypothesized that the frontal patients were not always taking
advantage of the cue because the task was solvable without it. In a
second experiment, the task was modified so that subjects were
required to process the cue in order to answer correctly. Results
are discussed in terms of the contribution of problem-solving
abilities to set-shifting impairments.
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