Grammatical class of base word and use of morpho-lexical representations in reading aloud derived nouns: a comparison between children with dyslexia and young skilled readers

Several data from both skilled readers and children with dyslexia revealed that the pronunciation of a derived low-frequency word can be improved by the recognition of its high-frequency base, thus indicating the use of morpho-lexical information in reading aloud. This study aims at investigating whether the grammatical class of base words contributes to the morpho-lexical effect on reading derived nouns. Many studies found that nouns and verbs are differently processed, thus the reading performance with derived nouns could be more affected by the activation of same-class bases (noun) than by the activation of verb bases. This difference may emerge in children with dyslexia due to their difficulty in processing verbal forms with respect to nominal forms: a difference that does not occur in young skilled readers (Egan and Pring, 2004). Method. Twenty 4th and 5th grade children with dyslexia and 40 skilled readers, matched by age, gender and cognitive development, participated in the study. Fifty nouns derived from noun bases (e.g. artista, artist) and 50 nouns derived from verb bases (e.g. punizione, punishment) were employed as experimental stimuli. They were presented randomly in a reading aloud task, along with 100 simple words ending with suffix-like orthographic sequence (e.g. intervista, interview; soluzione, solution) matched to the derived words for their psycholinguistic properties. Results. Generalized linear mixed models carried out on RT showed for skilled readers significant facilitatory first-level effects of whole-word and base frequency, irrespective of the grammatical class of the base word. As for children with dyslexia, the base frequency had a facilitatory effect only in case of noun bases, while the effect is null for verb bases. Conclusions. Data confirmed the use of morpho-lexical representations in reading aloud, but also the difficulty of children with dyslexia in the recognition of verb bases in written stimuli.