Nonword Repetition and Reading Skills in Children Who Are Deaf and Have Cochlear Implants

Article excerpt

Reading skills in hearing children are closely related to their phonological processing skills, often measured using a nonword repetition task in which a child relies on abstract phonological representations in order to decompose, encode, rehearse in working memory and reproduce novel phonological patterns. In the present study of children who are deaf and have cochlear implants, we found that nonword repetition performance was significantly related to nonword reading, single word reading and sentence comprehension. Communication mode and nonverbal IQ were also found to be correlated with nonword repetition and reading skills. A measure of the children's lexical diversity, derived from an oral language sample, was found to be a mediating factor in the relationship between nonword repetition and reading skills. Taken together, the present findings suggest that the construction of robust phonological representations and phonological processing skills may be important contributors to the development of reading in children who are deaf and use cochlear implants.

Introduction

Evidence from many studies suggests that children's reading skills are strongly related to their phonological processing skills (e.g., Bradley & Bryant, 1983; Byrne, Fielding-Barnsley, & Ashley, 2000; Hansen & Bowey, 1994; Liberman, 1971; Libermnn, Shnnkwoiler, & Liberman, 1989; Rapala & Brady, 1990; Scarborough, 1998; Watson & Miller, 1993). The term "phonological processing skills" encompasses a diverse set of cognitive processes measured by a variety of tasks, all of which require phonological encoding and rehearsal in phonological memory and/or accessing of phonological representations from the mental lexicon (see Brady, 1991; McBride-Chang, 1995; Troia, 2004; Wagner & Torgeson, 1987). Phonological processing tasks include, for example, behavioral measures that require phonological sensitivity, phonological awareness, automaticity or fluency in spoken naming, or phonological working memory skills, although sometimes phonological working memory is considered separately from other phonological processing skills (e.g., Gathercole & Baddeley, 1989; Hansen & Bowey, 1994).

Nonword repetition is a complex phonological processing task in which a participant is asked to listen to and then reproduce novel nonsense words. After only one exposure to a novel stimulus, the participant must immediately complete several subtasks: speech perception, decomposition and parsing of the speech stream into phonological units, rehearsal in phonological working memory, reassembly of the phonological units into an articulatory program and speech production. Thus, completion of the nonword repetition task relies upon successful use of several phonological processing skills (Bowey, 2001; Brady, 1997; Chiappe, Chiappe, & Gottardo, 2004; Munson, Edwards, & Beckman, 2005). Nonword repetition performance has been shown to be related to the development of reading skills in children (e.g., Apthorp, 1995; Brady, Poggie, & Rapala, 1989; Savage, 2006; Snowling, 1981; Taylor, Lean, & Schwartz, 1989).

Converging evidence from these and other studies has led several researchers to suggest that an important factor underlying both phonological processing skills and decoding skills is the quality of phonological representations (e.g., Bowey, 2001; Edwards, Beckman, & Munson, 2004; Elbro, Borstrom, & Petersen, 1998; Fowler, 1991; Fowler & Swainson, 2004; Katz, 1986; Metsala, 1999; Mody, Studdert-Kennedy, & Brady, 1997; Snowling, Wagtendonk, & Stafford, 1988; Studdert-Kennedy, 1987, 2002). That is, in broad terms, one possible cause of poor phonological processing and reading is weak or underspecified phonological representations of words in the mental lexicon. As children acquire lexical representations for spoken words, they have the opportunity to make generalizations about the sound patterns that occur in the ambient language so they are able to form abstract segmentai phonological representations with increasingly distinct categorical boundaries and increasingly robust within-category representations. …