ABSTRACT
In the present chapter a short review of learning disabilities subtyping is provided, with an emphasis on the different approaches that exist in the manner that reading disability subtypes are assessed and classified. It is concluded that one of the major concerns in subtyping research is the reliability and validity of classifications. Several studies are described that aim at the validation of one such a classification, namely in L- and P-type dyslexia. In these studies, the recording of electrocortical activity is used as a tool to delineate whether L- and P-subtypes differ in hemispheric control of reading and attentional processing, and whether this can explain differences in treatment outcomes. The results of those studies suggest that L- and P-type dyslexics do not differ in the early stages of attentional processing, such as directing attention and orienting to spatial locations, but that there are type-specific patterns of brain activity in later stages of stimulus processing.
