Phonological processing and reading abilities in adolescents and adults with severe congenital speech impairments

Abstract

Use of phonological coding during reading and short-term memory tasks was examined in 12 participants with congenital speech impairments who had reading grade levels of 3.0 or better. Six of the participants had no intelligible speech (anarthria) and six had moderate to severe speech production impairments (dysarthria). All 12 participants were capable of judging the homophony of printed words and nonwords, indicating that accurate phonological coding of text can occur in the absence of speech. Moreover, five participants with dysarthria and two with anarthria appeared to employ phonological coding in short-term memory tasks, as indicated by a phonological similarity effect in serial order memory, and also more weakly by a word length effect in serial order memory. These data indicate that persons with severe congenital speech impairments can learn to use phonological coding during reading and short-term memory tasks; articulatory coding is therefore not a necessary part of the phonological coding process in either word identification or short-term memory. In this study, four of the participants with anarthria did not engage in phonological coding during short-term memory tasks. These participants had more severe deficits in identifying printed words than other participants. Possible explanations of these individual differences are discussed.

• congenital anarthria
• congenital dysarthria
• phonological coding
• severe congenital speech impairments
• short-term memory