Abstract
Event-related potential (ERP) studies of word recognition have provided fundamental insights into the time-course and stages of visual and auditory word form processing in reading. Here, we used ERPs to track the time-course of phonological processing in dyslexic adults and matched controls. Participants engaged in semantic judgments of visually presented high-cloze probability sentences ending either with (a) their best completion word, (b) a homophone of the best completion, (c) a pseudohomophone of the best completion, or (d) an unrelated word, to examine the interplay of phonological and orthographic processing in reading and the stage(s) of processing affected in developmental dyslexia. Early ERP peaks (N1, P2, N2) were modulated in amplitude similarly in the two groups of participants. However, dyslexic readers failed to show the P3a modulation seen in control participants for unexpected homophones and pseudohomophones (i.e., sentence completions that are acceptable phonologically but are misspelt). Furthermore, P3a amplitudes significantly correlated with reaction times in each experimental condition. Our results showed no sign of a deficit in accessing phonological representations during reading, since sentence primes yielded phonological priming effects that did not differ between participant groups in the early phases of processing. On the other hand, we report new evidence for a deficient attentional engagement with orthographically unexpected but phonologically expected words in dyslexia, irrespective of task focus on orthography or phonology. In our view, this result is consistent with deficiency in reading occurring from the point at which attention is oriented to phonological analysis, which may underlie broader difficulties in sublexical decoding.
Highlights
During the last decade, the reading difficulties experienced by individuals with developmental dyslexia have been consistently associated with a deficit in phonological processing (e.g., Snowling, 2000; Ramus, 2002)
Evidence for weak phonological representations in developmental dyslexia is limited and largely derived from auditory tasks testing sensitivity to speech or acoustically modified stimuli within the context of tasks taxing working memory resources, and which usually require discrimination from a referent. This has prompted alternative proposals of mechanisms that contribute to phonological processing impairments involving working memory during phonological access (Blomert et al, 2004; Ramus and Szenkovits, 2008; Menghini et al, 2011), attentional engagement with phonological information (Hari et al, 1999; Hari and Renvall, 2001; Facoetti et al, 2006, 2008, 2010; Ruffino et al, 2010), visuo-attentional processes engaged in orthographic analysis (e.g., Ans et al, 1998; Valdois et al, 2004; Bosse et al, 2007; Vidyasagar and Pammer, 2010) or perceptual filtering (Roach and Hogben, 2007, 2008; Geiger et al, 2008), or a combination of such more generic cognitive processes (e.g., Pennington and Bishop, 2009; Menghini et al, 2010, 2011)
Post hoc analyses showed that this interaction was driven by significantly poorer accuracy in the homophone condition in the “ortho-semantic” task, compared with no differences between conditions in the “phonosemantic” task
Summary
The reading difficulties experienced by individuals with developmental dyslexia have been consistently associated with a deficit in phonological processing (e.g., Snowling, 2000; Ramus, 2002). Evidence for weak phonological representations in developmental dyslexia is limited (see Ramus, 2002; Blomert et al, 2004; Ramus and Szenkovits, 2008) and largely derived from auditory tasks testing sensitivity to speech or acoustically modified stimuli within the context of tasks taxing working memory resources, and which usually require discrimination from a referent (see Ahissar et al, 2006; Banai and Ahissar, 2006, for a discussion) This has prompted alternative proposals of mechanisms that contribute to phonological processing impairments involving working memory during phonological access (Blomert et al, 2004; Ramus and Szenkovits, 2008; Menghini et al, 2011), attentional engagement with phonological information (Hari et al, 1999; Hari and Renvall, 2001; Facoetti et al, 2006, 2008, 2010; Ruffino et al, 2010), visuo-attentional processes engaged in orthographic analysis (e.g., Ans et al, 1998; Valdois et al, 2004; Bosse et al, 2007; Vidyasagar and Pammer, 2010) or perceptual filtering (Roach and Hogben, 2007, 2008; Geiger et al, 2008), or a combination of such more generic cognitive processes (e.g., Pennington and Bishop, 2009; Menghini et al, 2010, 2011). If reduced sensitivity to phonological information is the source of reading difficulties in www.frontiersin.org
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call