Are the effects of psychomotor stimulant drugs on hyperactive children really paradoxical?

The improved "attention" exhibited by hyperactive children treated with amphetamine-like compounds is postulated to be related to a normal action of these drugs in producing stereotyped behavior. Such activity can be conceptualised as an increased "focusing" of attention, which would be expected to aid performance in tasks involving sustained concentration of attention, but impair performance on tasks involving reversals in cognitive strategy. These behavioural actions of the drugs can be linked to the functioning of central dopaminergic mechanisms.