Here, the investigators aimed to investigate the effects of THC (15 mg) on the retrieval of negative, neutral, and positive memories. The study used a placebo-controlled, within-subjects, crossover design with 24 participants. In each experimental arm, participants attend a session to encode stimuli, a second session 48 hours later in which their memories are tested for the stimuli from the first session followed by the encoding of object-scene stimuli and a working memory test, and a third session 48 hours later in which memory for the object-scene stimuli is tested. In the second session, two hours prior to memory testing, THC or placebo is administered. On the first and second sessions subjects complete mood questionnaires.