Visual attention and phonologicalpProcessing are both impaired in preschool children at risk of dyslexia

According to cognitive models of reading acquisition, the mastery of automatic grapheme-phoneme mappings (ie, the basis of phonological assembly) is a crucial prerequisite for the development of skilled reading. Phonological assembly--leading from a visual input to a linguistic output--requires, in addition to awareness of speech sounds, a graphemic parsing (GP) process that segments a letter string into graphemes. Indeed, both phonological segmentation and GP were found to be impaired in dyslexic children when compared to the age and reading level matched controls. A causal hypothesis suggests that the visuo-attentional mechanisms involved in GP are already compromised in preschoolers at risk of developmental dyslexia. To investigate this hypothesis, we measured the efficiency in orienting visual attention to a brief spatial exogenous cue when subjects were engaged in a task that required the identification of a target flanked by lateral noise (ie crowding condition). Our results show, for the first time, that children at risk of dyslexia (N=20) compared to controls (N=67) present a marked disorder of visuo-attentional orienting, in addition to the typical syllabic segmentation deficit. These results support the hypothesis of a causal link between a deficit of multi-sensory attention and developmental dyslexia.