Reading derived words by Italian children with and without dyslexia: The effect of root length

INTRODUCTION. Italian children with dyslexia experience difficulties in reading long stimuli and show an extremely slow and analytical reading behaviour. Recently, we showed that word naming times of children with dyslexia were shorter for stimuli composed of a root and a derivational suffix (e.g., CASSIERE, ‘cashier’), as compared to simple words of the same length and frequency not parsable in root + derivational suffix (e.g., CAMMELLO, ‘camel’) (Burani et al., 2008). We proposed that morphemes prove useful in processing linguistic stimuli in children with limited reading ability for whom most printed words are too large units to be processed as a whole. A similar facilitation on naming times due to morphological composition was found in skilled readers of the same age. However, whereas skilled readers showed a reading advantage of morphological composition for new words (pseudowords) and low-frequency words only, children with dyslexia were facilitated both in new words and in words of different frequency, including high-frequency words (Marcolini et al., in press). For both children with dyslexia and skilled readers, the facilitating effect on naming times was mainly driven by the root (Traficante et al., 2010). Overall, the facilitating effect of word’s morphological composition is larger in children with dyslexia as compared to skilled readers of the same age (see also Carlisle & Stone, 2005; Elbrö & Arnbak, 1996). The present study addresses the question of whether the facilitating effect found on lowfrequency derived word reading is moderated by the length of the root. For adult readers, shorter