Visually evoked potentials in boys with developmental dyslexia.

Pattern reversal visually evoked potentials were examined in a group of 16 boys with developmental dyslexia and 17 controls matched for sex, age and intelligence. Delineation of hypothesis was done with an independent pilot study. Wave form differences between groups could be observed over the left central lead in the pilot and replication study. Only 44% of the dyslexies showed a negative component between 110 and 215 ms after stimulus onset in comparison to more than 80% of the controls. The lack of this component was most prominent in dyslexies whose spelling scores were more than 1.5 standard deviations below their intelligence score.