Inhibitory deficits in reading disability depend on subtype: guessers but not spellers.

In this study, children with the guessing subtype of dyslexia (who read fast and inaccurately) were compared with children with the spelling subtype (who read slowly and accurately) on three aspects of executive functioning (EF): response inhibition, susceptibility to interference from irrelevant information, and planning. It was found that guessers were impaired in their ability to inhibit inappropriate responding on all tasks used to assess EF (the stop signal task, the Stroop task, and the Tower of London task). This raises the question of whether the specific reading disorder of guessers may be linked to the same executive deficits which underlie ADHD. In order to unite a fast/inaccurate reading style with executive deficiencies, an attempt is made to incorporate the concept of executive control into models of lexical activation.