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Abstract:
Based on the paradigm of the psychological refractory period
we asked whether interference in early perception processing can
account for multitasking deficits in older subjects (M= 57,7),
patients with Parkinsons disease (PD) and patients with frontal
lobe damage following closed head injury (CHI). Subjects were
presented with an auditory and a visual choice reaction task,
separated by varying SOAs. The perceptual difficulty of the visual
stimulus was manipulated by decreasing intensity. If the perception
stages of both task do not interfere, the locus-of-slack logic
(Schweickert, 1983) predicts an underadditive interaction between
SOA and Intensity manipulation on visual Task 2 reaction time.
Older subjects, patients with Parkinsons disease and CHI failed to
show this underadditive interaction under condition of high
perceptual intensity. In a second experiment we could show that
older subjects and patients with PD are capable of processing both
perception stages without interference under decreased intensity
conditions, whereas input processing could not be optimized for CHI
patients. These results indicate increased input interference
following frontal lobe damage. Probably, this increased input
interference is caused by a generalized inhibitory deficit,
resulting in decreased ability to coordinate different input
channels in dual-task situations. Supported by the BMB+F, IZKF,
University of Leipzig (01KS9504, project C09)
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