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Abstract:
Abstract: Department of Psychology, University of Bristol,
UK; Cornhill Hospital, Aberdeen, UK Experimental studies of healthy
adults and patients with Alzheimer's Disease have described a
specific decrement in patients' performance during dual-task. These
findings have been interpreted within two different theoretical
approaches. The single attentional theory claims that patients'
difficulty to perform a dual-task reflects a limited amount of
attentional resource. On the other hand, the co-ordination
hypothesis suggests that, regardless of the amount of resources
required by the two tasks, Alzheimer patients' failure occurs
because their inability to co-ordinate two different tasks at the
same time. Our study investigates directly the implications of this
debate. We tested two groups of normal subjects (8 young and 8
elderly people) and a group of 8 Alzheimer patients. Experimental
subjects were asked to perform under single and dual task
conditions with cognitive load varied systematically, manipulating
the level of the task difficulty (e.g. by increasing the total
number of digits to be recalled). Performance during single tasks
did not differ between the three groups, whereas during dual-tasks
patients showed a significant impairment. Nevertheless, patients'
decrement was not significantly affected by the overall increment
in the cognitive load. These findings support the co-ordination
hypothesis and a detailed analysis of our data shows an age effect
in allocation of resources.
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