Interactions Between Placebo Effects and Mindful Awareness State

"Participants will receive sham tDCS stimulation in a 20 minute long task.~Targets will be fitted with the tDCS stimulation electrode cap and instructed that they will receive 20 minutes of tDCS stimulation for the task. Sham tDCS will target the motor cortex at 2mA for 15 sec at the beginning of the session, and then the stimulator will turn off. The participant will then sit for the remaining time of the session with the electrode cap on their heads but turned off and not delivering stimulation.~All participants will receive sham tDCS stimulation (n=120)."

"In their second session, participants will receive real tDCS stimulation in a 20 minute long task.~Targets will be fitted with the tDCS stimulation electrode cap and instructed that they will receive 20 minutes of tDCS stimulation for the task. Real tDCS stimulation will target the motor cortex at 2mA for 20 minutes (full duration of task).~All participants will receive real tDCS stimulation (n=120)."

"Experimenters trained in high-competence and high-warmth will train Group 1 participants on mindful state induction (n=60). Participants will undergo two stages for this training: 1) pain education to increase beliefs in endogenous brain regulatory capacities; and 2) the Stanford Hypnotic Induction Profile (HIP) test of hypnotizability and hypnotic induction of a relaxed state receptive to suggestion.~In Stage 1, participants will receive education that pain and affect are processes designed to protect the body from danger, which are transmitted rapidly and automatically to the brain. In Stage 2, participants are (a) seated in an upright, alert posture; and (b) receive suggestions that the ability to attend to and discriminate affective perceptions is achievable and that suppressing attention to the body and focusing on the task will allow them to perform optimally under pressure. Mindful state induction will only be explicitly instructed during session 1 for Group 1 participants."

Participants in the No-mindfulness group will go through comparable stages but with different instructions. In the first stage, they will receive education about pain and affect as protective processes of the body. In the second stage, they will be seated in an upright, alert posture and receive suggestions to focus on the task and suppress attention to the body.