MENTAL ROTATON OF LETTERS IN DYSLEXICS AND IMPLICATIONS FOR DIAGNOSIS AND EDUCATIONAL TREATMENT

A classical mental rotation task (Cooper & Shepard, 1975) was performed with dyslexics and non-dyslexics. Group differences were found for mean reaction time but there was no difference in mental rotation effects between the groups. The results were interpreted within the framework of the Functional Coordination Deficit model (Lachmann, 2002). It was concluded that dyslexics rotate the letters mentally just as good as non-dyslexics but have a problem to finally decide, whether the letter is normal or mirrored. This problem occurred because of a failure in suppression of symmetry in the representation of graphemes. Dyslexics represent letter like objects. Therefore, they fail to discriminate between orientational alternatives and for the same reason fail to establish unambiguous relation between grapheme and phoneme representations. According to the International Classification of Diseases, developmental dyslexia is a specific disability in learning to read and to spell adequately despite of at least normal intelligence, adequate instruction and socio-cultural opportunities. Furthermore, sensory defects in vision and hearing should be excluded as to be responsible for the problems in reading and writing. One of the major symptoms of dyslexia are reversal errors, that is, the children confuse letters whic