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Abstract:
Deficits in one's capacity to perform intermodality attention
shifting has proved to be sensitive for persons with cerebellar
dysfunction (Akshoomoff & Courchesne, 1992). In the Focus
Auditory and Focus Visual conditions the participant responds only
to a single auditory or visual stimulus. In the Shift condition the
participant is instructed to press to the first auditory target and
then alternate their responses between auditory and visual. Three
participants with Williams syndrome were examined who had completed
MRI and mid-sagittal area measurements of the vermis had been
ascertained. One case was hypoplastic, one hyperplastic and one had
measurements in a normal. Each of the three Williams syndrome
participants showed a pattern of impairment in being able to
rapidly shift their attention when cue to target intervals were
less then 2.5 seconds. Their performance was very similar to
reports of persons with autism and persons with cerebellar
abnormalities (Courchesne, Townsend, Akshoomoff, Saitoh,
Yeung-Courchesne, Lincoln, James, Haas, Schreibman, & Lau,
1994). Performance was not impaired in the Focus conditions. The
results are consistent with the presence of cerebellar dysfunction,
and are the first to suggest problems with shifting attention in
persons with Williams syndrome. Research supported by NIH grant to
Ursula Bellugi, P01 HD33113.
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