The optimal stimulaton theory (which proposes that hyperactive children are more readily underaroused than nonhyperactive children and should thus derive greater gains from stimulation added to repetitive copying tasks than comparisons) was tested with 16 adolescents, rating high on attention and behavior problems, and 16 controls. Matched pairs were randomly assigned to treatment order (high stimulation colored letters followed in two weeks by low stimulation black letters or the reverse order) and to level of information (stimulation added to difficult letter parts or added to random letters), counterbalanced for treatment order and level of information within each order. In support of the theory and analogous to stimulant drug effects, the major findings indicated that hyperactive adolescents performed better with high stimulation task stimuli than with low stimulation stimuli relative to the opposite performance pattern of controls. Differential responding was significant for experimental but not control children. (Author/SW)