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Abstract:
Goal. Patients with frontal brain damage can be impaired at
selecting task-relevant information for action. For example,
distractor objects may interfere with action preparation. In an
action task, we studied distractor interference in a patient with
frontal brain damage. The aim was to study the effect of attention
on action selection on trials in which targets and distractors
switched. Method. FK was a 31-year old right-handed male with
bilateral medial frontal and temporal damage. In the experiments,
FK responded to a target cup in the presence of a distractor cup,
with the target cued by colour or location. The effect of cued and
uncued relevant dimensions on performance was examined. FK made
both manual and verbal responses. Results. FK was impaired at
selecting the target when the cued target colour, but not its
location, changed on successive trials. This cue-specific
"carry-over" effect was enhanced when a temporal delay occurred
between a cue and the response; it disappeared when a between-
trial delay occurred, or when FK made verbal responses. In
addition, there was differential interference according to the
orientations of targets and distractors, which preferentially
"afforded" reach actions. Conclusion. FK showed an attention
switching deficit which was limited to action, to task-relevant
cued dimensions, and to specific cue-response intervals. This
deficit reflects the influence of an object previously selected for
action.
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