2. Go/No go task - Duration: 10 minutes During this procedure, participants will respond to two different letters by selecting one of two buttons that are associated with each letter. They will be asked to inhibit their response if the letter they are viewing is the same as the letter just viewed. It is intended to measure cognitive control. Drug-related pictures will also be included as distractors to examine their effects on performance and EEG/event-related potential (ERP) measures.