Phonological Restriction Knowledge in Dyslexia: Universal or Language-Specific?

Abstract

Developmental dyslexia is the most studied and well-documented of the specific learning disabilities in school-age children across languages, which reaches from 5-to-17.5% individuals (e.g., Shaywitz & Shaywitz, 2005; Snowling, 2001). There is now a consensus that developmental dyslexia stems from a genetic neurodevelopmental disorder that does not depend on inadequate intellectual or educational backgrounds (e.g., Lyon, Shaywitz, & Shaywitz, 2003; Sprenger-Charolles, Cole, Lacert, & Serniclaes, 2000; Vellutino, Fletcher, Snowling, & Scanlon, 2004). There is considerable evidence for a phonological deficit as the major correlate of language disabilities in dyslexia, which underpins the cognitive disorder (e.g., Ramus, Rosen, Dakin, Day, Castellote, White, & Frith, 2003; Ziegler & Goswami, 2005). However, an outstanding, long-lasting question that remains unclear, even unanswered, is what underlies the phonological deficit in dyslexia (e.g., Ramus, 2001). Three main directions have been proposed to account for the phonological deficit: 1) limited phonological short-term memory; 2) degraded, under-specified or, conversely, overspecified phonological representations; 3) speech perception disorders. However, the degraded, under-specified phonological representation hypothesis that is basically referred to accounts for the dyslexics’ phonological deficit has been recently challenged: it has been suggested that the dyslexics’ phonological deficit relies on difficulties to store, access, and retrieve the phonological representations (e.g., Ahissar, 2007; Ramus & Szenkovits, 2008; Szenkovits & Ramus, 2005). To date, to reconcile both views, it has been proposed that the phonological deficit results in multi-dimensional difficulties that include difficulties to learn and manipulate the speech units as well as difficulties to store, access, and retrieve the phonological representations (e.g., Snowling, 2001; Ziegler, Castel, Pech-Geogel, George, Alario, & Perry, 2008). Despite this tentative proposal, there is no consensus. Here, I propose to draw an up-to-date portrait of an alternative option that has not been studied so far to disentangle whether another possible source of the phonological deficit in dyslexia may be envisaged: Are dyslexics sensitive to universal phonological knowledge?