During each of 4 functional runs, participants first experienced a resting baseline for 30 seconds, and then heard the instruction “close your eyes and imagine the following situation as if it were happening right now.” Then, one of four individualized scenarios was played via headphones (two stressful/negative and two neutral/peaceful scenarios, presented in random order). Each scenario lasted 3 minutes, and was followed by the instruction “please stop imagining and lay still,” followed by a cooldown period. Before and after each run, participants rated their stress and craving on a 10-point scale; and after each scenario they rated the vividness of the imagined scenario.