The underlying cognitive, motivational, and neural pathways leading to symptoms of Attention Deficit/Hyperactivity Disorder (AD/HD) remain largely unclear. In order to develop optimal treatments for this prevalent disorder, it is crucial to understand the underlying mechanisms associated with it. A promising mechanism proposed to play a crucial role in AD/HD is the mesocortical dopamine system, which has also been suggested to underlie the processing of reward information and motivation. This project will examine reward preferences in an effort to elucidate a possible motivational mechanism underlying AD/HD. Behavioral research with single-choice paradigms has suggested that AD/HD is associated with a tendency to choose small immediate rewards over large delayed ones. However, there is no research thus far in children with AD/HD that examines preferences for small immediate and larger delayed rewards when magnitude of the immediate reward and delay of the large reward vary. By applying a temporal discounting paradigm (temporal discounting refers to the decrease of perceived value as a function of delay) in which magnitudes of immediate rewards and delays of large rewards are varied, this study will examine how reward preferences in children with AD/HD vary as a function of delay and reward magnitude. A second aim is to study the effect of maximum total gain on temporal discounting (TD) in AD/HD. Based on previous research, it may be predicted that if the maximum total amount to be won in a task is high, children with AD/HD may be more inclined to wait for the large reward. The proposed study will formally test this hypothesis. We will use a TD task in which participants will be presented with choices between a smaller immediate reward and a larger delayed reward. The sizes of the immediate and delayed rewards, the delay durations, and the maximum total gain will be varied. We predict that steep TD of large rewards is associated with AD/HD when maximum total gain is relatively small and when the magnitude of the delayed reward is relatively small. We plan to include 36 adolescents with AD/HD, and 36 healthy controls. Participants will be in the age range of 6 - 12, matched for sex and age, and will be required to have an IQ above 70. This research will contribute to a more sophisticated understanding of the role of reward preferences in symptoms of AD/HD. Ultimately, such an understanding will improve treatment strategies for this disorder. [unreadable] [unreadable] [unreadable]