 On the last day of treatment Day 7, participants will come to the Department of Experimental Psychology of the University of Oxford around 2 pm, which corresponds to time when the drug reaches its peak in blood levels. They will be asked to complete again part of the questionnaires administered on the first day and then they will complete a battery of neuropsychological tests including attentional tests, facial expression recognition tests and emotional regulation tests, as used in our previous studies. During the emotional regulation test an ECG will also be recorded. The testing session will last approximately 3 hours. 