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Abstract:
Abstract: Research on the source of auditory comprehension
deficits in aphasia carried out in the late 1970's and early 1980's
showed fairly conclusively that left hemisphere damage produces at
worst only mild phonemic perception deficits. Further, because
substantial phonemic perception problems do not arise from damage
anywhere in the left hemisphere, but are associated with bilateral
superior temporal lesions, it is reasonable to hypothesize that
phonemic perception is supported by superior temporal regions
bilaterally. Despite this evidence, the view persists that phonemic
perception is strongly left lateralized. We present data which
replicates earlier work on phonemic perception in aphasia and
extends it by examining the phonemic perception abilities of the
isolated hemispheres of a split brain patient (JW). Nine aphasics
with unilateral left hemisphere lesions performed an auditory
word-to-picture matching task which contained along with the
target, a phonological, semantic, and unrelated foil. JW listened
to auditory words and then made a match/no-match decision on
individual pictures which were lateralized to one or the other
visual field. Replicating previous work, aphasics committed more
semantic than phonological errors. JW performed well overall (LVF =
92%, RVF = 94% correct), and was able to accurately discriminate
matching items from phonological foils in both hemispheres
(A-prime: LVF = .96, RVF = .995). These findings provide additional
support for the view that both hemisphere support (or can support)
speech perception.
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