According to the American Psychiatric Association (DSM-III-R, 1987): Often deficits in expressive language and speech discrimination- may be severe enough to additionally diagnose Developmental Expressive, Receptive Language Disorder or Developmental Expressive Writing Disorder. Visual perceptual deficits appear in about 10% of the dyslexic population. Disruptive Behavior Disorders (like ADD).

According to the American Medical Association (Council on Scientific Affairs, 1989): poor coordination, poor spatial reasoning, right-left directional confusion, poor temporal orientation, poor color naming, poor visual labeling, mixed cerebral dominance, linear tracking errors, and failure to develop a “leading eye.” Often demonstrate behavioral difficulties secondary to reading difficulty.