Differential effects of methylphenidate and self-reinforcement on attention-deficit hyperactivity disorder

Six boys aged 9 to 12 years attended a tutoring class focusing on reading for 30 minutes each morning. The investigators employed a modified Latin-square design in which each child began with a 5-day baseline phase followed by six 10-day treatment phases that used drug placebo, noncontingent reinforcers, 0.3 mg/kg methylphenidate, 0.7 mg/kg methylphenidate, and self-reinforcement in various combinations. Amount of academic performance was the major measure of outcome and the target behavior of self-reinforcement. Drug placebo and noncontingent reinforcers had no systematic impact. Methylphenidate had differential effects across the recorded behaviors. Self-reinforcement improved the target behavior; the mean effect size for self-reinforcement was 2.66. The combined effects of methylphenidate and self-reinforcement on academic performance were greater than either of the treatments given alone (mean effect size = 2.89).