Use of amphetamine-type substances including MDMA (ecstasy), methylphenidate (Ritalin), and novel cathinone designer drugs is prevalent in our society. In particular, the pharmacology and toxicology of the cathinones is poorly known and will be characterized in this project. In addition, we investigate the pharmacological effects of MDMA and Ritalin with regard to effects on emotion recognition, empathy, and social behavior in humans. Social cognition (emotion recognition and empathy) is critical for human social interactions. MDMA produces subjective feelings of openness and closeness to others and is said to have “empathogenic” effect. However, it is unknown whether MDMA indeed improves affective perception and enhances emotional or cognitive empathy. Such effects are relevant with regart to the recreational use of MDMA but also to its potential therapeutic use in psychotherapy. Methylphenidate is widely used in the treatment of attention deficit hyperactivity disorder (ADHD). In addition, methylphenidate is also abused as a party drug and its use for cognitive enhancement as so-called ‘smart drug’ has become a focus of concern. Whether methylphenidate use affects social cognition is not known. However, it is possible that part of the therapeutic benefits of this amphetamine derives from enhanced face emotion recognition which has been shown to be impaired in children with ADHD. Our clinical studies will also produce important data on the pharmacological mechanism of action of amphetamines that will inform emergency physicians on how to treat intoxications with these drugs.