Conclusions are made in reference to Barkley's theory and implications are explored.

Children with ADHD adjust their behavioral responses to changing reinforcer availability less than typically developing children, when reinforcement is intermittent and the association between an action and its consequences is uncertain. This may explain the difficulty children with ADHD have adapting their behavior to new situations, with different reinforcement contingencies, in daily life.

Punishment exerted greater control over the response allocation of children with ADHD with increased time on task. Children with ADHD appear more sensitive to the cumulative effects of punishment than typically developing children.

Background: Research on altered motivational processes in ADHD has focused on reward. The sensitivity of children with ADHD to punishment has received limited attention. We evaluated the effects of punishment on the behavioral allocation of children with and without ADHD from the United States, New Zealand, and Japan, applying the generalized matching law. Methods: Participants in two studies (Furukawa et al., 2017, 2019) were 210 English-speaking (145 ADHD) and 93 Japanese-speaking (34 ADHD) children. They completed an operant task in which they chose between playing two simultaneously available games. Rewards became available every 10 seconds on average, arranged equally across the two games. Responses on one game were punished four times as often as responses on the other. The asymmetrical punishment schedules should bias responding to the less punished alternative. Results: Compared with controls, children with ADHD from both samples allocated significantly more responses to the less frequently punished game, suggesting greater behavioral sensitivity to punishment. For these children, the bias toward the less punished alternative increased with time on task. Avoiding the more punished game resulted in missed reward opportunities and reduced earnings. English-speaking controls showed some preference for the less punished game. The behavior of Japanese controls was not significantly influenced by the frequency of punishment, despite slowed response times after punished trials and immediate shifts away from the punished game, indicating awareness of punishment. Conclusion: Punishment exerted greater control over the behavior of children with ADHD, regardless of their cultural background. This may be a common characteristic of the disorder. Avoidance of punishment led to poorer task performance. Caution is required in the use of punishment, especially with children with ADHD. The group difference in punishment sensitivity was more pronounced in the Japanese sample; this may create a negative halo effect for children with ADHD in this culture.