A study conducted by Dr. Sydney S. Zentall and associates of Purdue University in Indiana tested the "Optimal Stimulation Theory" proposing that hyperactive children are less tolerant of lower levels of arousal than non- hyperactive children and therefore should derive greater gains from stimulation (such as color) added to repetitive copying tasks.
To test this hypothesis, 16 adolescents, rating high on attention and behavior problems, were matched on the basis of age and poor handwriting performance to 16 adolescents without this problem. 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 the level of information (color added to difficult letter parts or added to randomly selected letters). The major findings indicated that attention-problem adolescents performed better with high-stimulation task stimuli than with low.
In general, the findings are as powerful as the effects produced by stimulant drugs. Thus, environmental manipulations such as color may one day replace the radical manipulations of a child's internal environment that are produced by stimulant drugs.