Institute of Psychology, Maria Curie-Sklodowska University

The study investigates the relation between developmental dyslexia, IQ and complex motor skills involving some cognitive and executive functions. The mechanisms underlying the co-existence of disabilities related to reading and writing on the one hand and motor skills on the other hand, still need to be clarified. In the current study it was hypothesised that the level of intelligence may contribute to complex motor skills in dyslexia. The study involved 58 students with developmental dyslexia (age 9.08 yrs; SD = .06) and 50 students constituting a control group (age 9.09 yrs; SD = .06). The measurements were performed using WISC-R, two subtests from the Dyslexia 3 Test, and four complex motor tasks. Children with dyslexia present problems in complex motor tasks, which involved learning of movement sequences and mental rotation. This finding may support the cerebellar deficit hypothesis in dyslexia. Complex motor skills are significantly related to children’s intelligence level or to the interaction of intelligence and dyslexia. Child’s intelligence explains from 7.5% to 35% of the variance in complex motor skills.