Sensitivity to distributional properties of the orthography in the spelling of Italian children with dyslexia

The study examines statistical learning in the spelling of Italian children with dyslexia and typically developing readers by studying their sensitivity to probabilistic cues in phoneme-grapheme mappings. In the first experiment children spelled to dictation regular words and words with unpredictable spelling that contained either a high- or a low-frequency (i.e., typical or atypical) sound-spelling mappings. Children with dyslexia were found to rely on probabilistic cues in writing stimuli with unpredictable spelling to a greater extent than typically developing children. The difficulties of children with dyslexia on words with unpredictable spelling were limited to those containing atypical mappings. In the second experiment children spelled new stimuli, that is, pseudowords, containing phonological segments with unpredictable mappings. The interaction between lexical knowledge and reliance on probabilistic cues was examined through a lexical priming paradigm in which pseudowords were primed by words containing related typical or atypical sound-to-spelling mappings. In spelling pseudowords, children with dyslexia showed sensitivity to probabilistic cues in the phoneme-to-grapheme mapping but lexical priming effects were also found, although to a smaller extent than in typically developing readers. The results suggest that children with dyslexia have a limited orthographic lexicon but are able to extract regularities from the orthographic system and rely on probabilistic cues in spelling words and pseudowords.