Linguistics Research Today is a free monthly online journal that collates and summarizes the latest research about Linguistics, including details on human language, phonetics, syntax, phonology.

Lexicality and stimulus length effects in Italian dyslexics: role of the overadditivity effect.

Di Filippo G, de Luca M, Judica A, Spinelli D, Zoccolotti P

Neuropsychology Unit, IRCCS Fondazione Santa Lucia, Roma. gloria.difilippo@uniroma1.it

The effect of lexicality and stimulus length was studied in 32 third- and fourth-grade Italian dyslexics and in 86 age-matched controls. A visual lexical decision task was used. As proposed by Faust et al. (1999), the results were analyzed in terms of raw reaction time (RT) data and using the z-score transformation to control for the presence of overadditivity effects. In terms of RTs, dyslexics showed a larger difference between words and nonwords (lexicality effect) and between short and long stimuli (length effect) than proficient readers. When data were transformed into z scores, only the group by length interaction remained significant while that with lexicality vanished. This pattern indicates that stimulus length has a specific role in Italian dyslexics' reading deficit; in contrast, slowness in responding to nonwords was not specific but was interpreted as one aspect of dyslexics' general inability to deal with alphabetical material (overadditivity effect).

Published 6 June 2006 in Child Neuropsychol, 12(2): 141-9.
Full-text of this article is available online (may require subscription).

© 2005-2008 Linguistics Research Today. All Rights Reserved.