Objective: To investigate the relationship of static reversals, handedness and gender to reaction time variability (RTV) in a sequentional sample of 1,109 children referred to a child psychiatry clinic for investigation of possible ADHD. Method: A DSM-III ADHD diagnosis and ADHD severity ratings (mild, moderate, and severe) by the present investigator was recorded. The age at which the children were still manifesting static reversals as reported by their mother, and right, left, or both-handedness as reported by the mother and observed by the investigator, were noted. Results: The age that letter reversals were still manifested was significantly associated with RTV for male and female children. Conclusions: The findings may represent an early manifestation of a failure of suppression of visually symmetrical information and/or a failure of default mode suppression