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Abstract:
Models of reading in neuropsychological literature sometimes
include only two routes from print to sound, a lexical-semantic
route and a sublexical phonological route. Some researchers
hypothesize an additional route that involves the direct connection
of lexical orthographic representations and lexical phonological
representations. This so-called "third route" has been invoked to
account for preserved oral reading of some patients who show severe
semantic impairments and a disruption of the sublexical
phonological route. In their summation hypothesis, Hillis and
Caramazza (1991, 1995) have proposed that reading in these cases
could result from a combination of partial lexical-semantic
information and partial sublexical phonological information, thus
obviating the need for the third route. A dual-route computational
model is implemented to demonstrate the predictions derived from
the summation hypothesis regarding the influence of semantic
disruptions and of the sublexical route on word reading times. The
current study compares the performance of this model with the
performance of a phonological dyslexic patient (ML) who exhibits
preserved word reading even for items he could not name along with
a nonword reading impairment. The relationship between ML's naming
and reading, and the influence of semantic variables on his reading
are not consistent with the predictions derived from the summation
hypothesis. Thus, the results of this examination are interpreted
as supporting the existence of the third route.
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