Skill acquisition refers to the process of improvement of performance following practice experience. This process is the basis for generation of a long-lasting memory. Individuals with Attention Deficit Hyperactivity Disorder (ADHD) have been shown to be impaired on some performance aspects of previously learned skills, an impairment that is often ameliorated, at least temporarily, by psychostimulant medication (the standard therapy in ADHD). The proposed study aims to define the course of learning and of generation of long-term memory consolidation in individuals with ADHD, and to essay the effectiveness of psychostimulant medication on both the learning and retention of the skills.