 This experiment employs a mixed-measures, counter-balanced design. Participants will complete two measures of reward processing i.e. the revised monetary incentive delay MID task and a temporal difference error task TDEjuice task while undergoing BOLD EPI fMRI. The scanning procedure will be repeated for all subjects, such that each participant undertakes 2 sessions. Cocaine-dependent individuals will receive either two injections of cocaine 30 mg70 kg body weight; intravenous IV administration or two injections of saline during scanning. Within each session, each IV injection will be given approximately 10 minute prior to the start of one of the reward measures. The order of cocaine and saline scans will be randomized and participants will be blind to the experimental condition prior to participation. 