A third route for reading? Implications from a case of phonological dyslexia

Models of reading in the neuropsychological literature sometimes only include two routes from print to sound, a lexical semantic route and a sublexical phonological route. Other researchers hypothesize an additional route that involves a direct connection between lexical orthographic representations and lexical phonological representations. This so-called 'third route' has been invoked to account for the 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 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. The present study examined the case of a phonological dyslexic patient (ML) who exhibited preserved word reading, even for items he could not name, along with a non-word reading impairment. The relationship between ML's naming and reading, and the influence of semantic variables on his reading were examined. The results of this examination are interpreted as supporting the existence of the third route.