Thesis title: Comorbidity of Learning Disorders: Testing a proximal model of reading, spelling, and math
Specific Learning Disabilities (SLD) are defined to be “specific” as they occur in the absence of deficits in basic cognitive skills, despite normal exposure to school activities. Research on SLD and its cognitive precursors is characterized by a multitude of approaches and perspectives, but in general, has focused on delving into a single disorder (reading, spelling, or doing math). The main problem with these types of approaches is that they fail to account for the presence of pervasive comorbidities among SLD (Trenta, De Filippo & Zoccolotti, 2009; Nicolson & Fawcett, 2007; Pennington, 2006). In recent years, research on this topic has clearly indicated that this is a widespread phenomenon (Van der Sluis et al., 2004; Fuchs & Fuchs, 2002), and that this co-occurrence affects not only disorders that fall within a particular domain (homotypic comorbidity), but also disorders that are more "distant" (heterotypic comorbidity).
Although over the years some authors have attempted to address the issue of comorbidity, the prevalent tendency has been to invoke general cognitive factors (working memory, perception, attention) to account for the phenomenon. This type of approach can be termed as “distal”, in that the relationship between the complex behaviors being examined and these general cognitive abilities, is not fully explicated, remaining implicit. By contrast, a “proximal” approach aims to indicate the direct cognitive antecedents of both the specific components of each disorder and their overlap.
In this context, the present research aims to test a previously developed cognitive architecture tested on a typical-development sample (Zoccolotti at al. 2020a; 2020b), capable of unitarily considering reading, spelling, and mathematical skills, on a sample of children with learning disabilities. Specifically, the working hypothesis was that a deficit in the automatization of individual instances, as postulated by Logan (1984), may underlie comorbidity among reading, spelling, and math disabilities. With this purpose, a group of 49 children with SLD was tested and compare with an age-matched control group, using measures of reading, spelling, math, and general cognitive ability.