1. To examine whether Ritalin has analgesic properties in healthy subjects.
2. To examine if Ritalin analgesic effect is a pain specific phenomenon or a part of a broader, non-specific effect on high mental functions.

Inclusion Criteria:

• Male subjects between the ages of 20 to 40
• Healthy subjects without known disease and without any chronic pain
• Subjects without known cognitive problems, which can understand the research and its goals
• Subjects who are not taking any medications
• Subjects without hearing problems
• Subjects without attention deficit disorder (ADHD) problems

Exclusion Criteria:

• Subjects who are known to suffer from any disease or any chronic pain
• Subjects taking psychotropic drugs (except Ritalin) or any analgesics
• Subjects who have any contradictions for ritalin administration
• subjects with suspected cognitive disability