chapter  15
The cerebellar deficit theory of developmental dyslexia: evidence and implications for intervention
BySHAHRZAD IRANNEJAD, ROBERT SAVAGE
Pages 17

A mild deficit in the cerebellum has been proposed to underlie a wide range of cognitive and behavioural indicators of dyslexia that were formerly explained by the phonological deficit hypothesis and double-deficit models of reading disability, as well as other unexplained symptoms observed in dyslexia (Nicolson, Fawcett, & Dean, 2001). In its earliest form cerebellar deficit theory was introduced within a cognitive framework of automaticity, postulating that dyslexic children have difficulties in becoming fluent in any learned skill (Nicolson & Fawcett, 1990). The incorporation of a neurological (cerebellar) basis underlying this apparent automaticity deficit is a more recent development (Nicolson & Fawcett, 1999; Nicolson et al., 2001). However, the specific role of the cerebellum in dyslexia is not strongly established as there are some inconsistencies in the existing evidence. Moreover, empirical evaluations of an intervention based on the cerebellar deficit theory do not present convincing evidence, largely due to methodological issues. Consequently we argue that this area requires further investigation.