“…A substantial body of research evidence and clinical data supports the view that many of the behaviors previously included in descriptions of minimal brain dysfunction (MBD) or hyperactivity are signs of a disorder of attentional processes (e.g., Cantwell, 1983; Douglas, 1972; Douglas & Peters, 1979; Dykman, Ackerman, Clements, & Peters, 1971; McMahon, 1984; Rosenthal & Allen, 1978; Whalen & Henker, 1980), although there is continuing rigorous debate and need for further definition and study. The central issue in this article is not whether a cluster of problem behaviors characterized as hyperactivity or ADHD exists, but whether this cluster of behaviors, with its frequently associated learning/cognitive difficulties and conduct problems, is in fact a manifestation of a measurable deficit or deficits in attentional processes.…”