On the production of functional categories in children with dyslexia. A study on pronouns, articles and prepositions

Developmental Dyslexia (DD) is traditionally defined as a neurobiological disorder concerning the failure in learning to read properly in individuals who have normal intelligence. It is widely accepted that at the base of DD there are persistent phonological impairments (Catts, 1989; Ramus et al., 2003; Snowling, 2000). Actually, dyslexia is often characterized by difficulties that go far beyond the phonological problems, as other language components are also affected in diagnosed dyslexic subjects. In fact, researchers found that people with dyslexia also exhibit specific grammatical deficits related to difficulties in production and comprehension of complex syntactic constructions, such as relative clauses (Bar-Shalom et al., 1993; Robertson and Joanisse, 2010; Wiseheart et al., 2009; a.o) and passive sentences (Leikin and Assayag-Bouskila, 2004; Stein et al., 1984; Reggiani, 2009; a.o). In addition, dyslexics have difficulties with verbal morphology (Rispens et al., 2004), pronouns (Waltzman and Cairns, 2000) and negation (Vender and Delfitto, 2010; Scappini et al., 2015). This thesis provides a contribution to a new research line, now under development in Italy, dealing with the issue of oral language deficits in children with DD (Arosio et al., in press; Guasti, 2013; Guasti et al., 2015). Through elicited production techniques, we investigated the abilities of dyslexic children (aged 8-10 years) in using three types of functional words, namely definite articles, articulated prepositions and object clitic pronouns, as the production of expressions containing each of them involves different degrees of morphosyntactic complexity. We designed an experimental protocol consisting of three independent tasks through which we elicited respectively: 1) proclitic pronouns, 2) proclitic and enclitic pronouns, 3) definite articles and articulated prepositions. Our goal was twofold. First, we verified whether and to what extent dyslexia affects the oral production of different linguistic structures containing functional categories. Then, we aimed at understanding whether dyslexics’ problems can be due to morphosyntactic reasons. The results show that, with respect to age-matched controls, dyslexic children have significant difficulties in the production of certain functional elements. Interestingly, their difficulties increase when the degree of morphosyntactic complexity is greater, as a higher load of Working Memory resources is required. Overall, our analysis demonstrates that a) children with dyslexia have no problem in the production of definite articles, since it does not require any syntactic movement opertation; b) they encounter some difficulties with prepositions, as these elements are obtained through a process of incorporation (P+D); c) they display significant problems with clitic pronouns, in particular with proclitics. In comparison to the other two elements, in fact, the production of proclitics involves a particular syntactic movement that results in a non-canonical word order in Italian. Therefore, we believe that the phonological difficulties found in dyslexic children may be extended to the morphosyntactic domain and that their limited working memory capacity is also reflected in the oral production of particular linguistic structures.