The study assesses the effect of Ritalin on working memory,attention,and decision-making measures in adults with ADHD and compares it to its effect on healthy adults, in a double-blind crossover design.We hypothesize that Ritalin will result in better performance in all measures,and that the improvement will be greater in the ADHD group.

Inclusion Criteria:

• adults in the age of 21-50

Exclusion Criteria:

1. People diagnosed with a clinical disorder other than ADD/ADHD that may impair their performance in the tasks used in the study.
2. People for whom there is a contra-indication for consuming Ritalin.
3. Pregnant women and nursing women;