Intervention
Prior to the baseline session, participants were randomized to one of four conditions (phase 1) using a 2 × 2 factorial design: (1) stress task and smoking cue, (2) stress task and neutral cue, (3) control task and smoking cue, or (4) control task and neutral cue. The stress task was the Montreal Imaging Stress Test (MIST) [The MIST (or its control version) was immediately followed by a five-minute video cue presentation. For participants in the smoking cue condition, these video clips were similar but non-identical to those presented at baseline. For participants in the neutral cue condition, cues consisted of ten 30-second clips depicting non-smoking activities (see Supplementary Methods). Neutral and smoking cues were matched on number of people in each clip, their approximate age, ethnicity, distance from the camera, and lighting.All four phase 1 conditions were followed by a 10-minute break during which participants remained seated in front of a black screen. They then underwent a 60-minute extinction protocol (phase 2). This entailed four rotations of: a five-minute video with smoking-related content (composed of similar but non-identical clips to those presented in the baseline visit), a five-minute presentation of smoking images (with each image presented for 3 seconds, see Supplementary Methods), and five minutes of manipulating smoking paraphernalia (e.g., lighter, cigarettes).Immediately prior to and after phase 1, and immediately after phase 2, HR, SC and BP were measured, and participants completed the TCQ-SF and QSU-Brief. Participants remained in the laboratory for one hour following completion of the questionnaires to minimize the chance that they would reengage the association between cigarette use and smoking-related cues. Participants who underwent the stressful MIST were debriefed. All participants were asked to see how long they could go without smoking after the session.