Reading disabilities in a language with transparent orthography

The aim of the present chapter is to provide some empirical evidence about underlying mechanisms that are involved in the explanation of reading disabilities in a language with transparent orthography (i.e., Spanish). Previously, we analyze some phonological and orthographical specificities of English and Spanish in order to describe their implications on psycholinguistic processing. Specifically, our analysis is centered on word recognition processes, therefore we describe some psycholinguistic parameters which have been used in Spanish studies in order to determine to what extent some reading models (e.g., dual models) are functional in a transparent orthography. If reading mechanisms are the same for different alphabetical writing systems, then the pattern of results found in English should be expected in Spanish as well. Likewise, taking into account that dual-route theory has been used to explain the mechanisms underlying developmental dyslexics' word reading, we review some research carried out in Spanish which has been designed to test whether the phenotypic pattern in a transparent orthography matches that found in English. But before we discuss these results we also review some problems related to the definition of reading disorders. The definition for developmental reading disorder relies on a discrepancy between expected and actual achievement. One of the most important tests for the credibility of and justification for the discrepancy definition of dyslexia is its ability to identify a unique group of individuals with reading problems that is different from ordinary poor readers who have no discrepancy. We review some bibliography literature on this topic in English, and we provide additional empirical evidence from Spanish studies which demonstrate that the IQ discrepancy based definition for dyslexia should be abandoned in favor of a definition which incorporates the phonological deficit hypothesis. On the other hand, we also review some studies about the relative influence that different forms of orthographic units (e.g., syllables, onset-rime, etc.) on the explanation of reading disabilities as a function of orthographic systems. And finally, we provide empirical data relevant to the issue whether specific reading disabilities fit a developmental tag or deficit model in a transparent orthography.