Context Interventions: Social Modeling and Initial Treatment Experience

In this experiment, the investigators study the brain pathways underlying several promising context interventions that enhance the strength of placebo effects. Specifically, the investigators examine the separate and joint effects of two of the most powerful context interventions: Social modeling-observing someone else being effectively treated-and prior treatment success or failure experiences. Participants will be randomized into 4 groups (Social modeling: observed success vs. observed failure and Conditioning: experienced success vs. experienced failure). The objectives are to investigate the placebo effect on pain relief and aversive image stimuli between and within-subjects. Each group will undergo a behavioral induction phase, fMRI placebo test phase, and an identical 3-month follow up fMRI placebo test phase. Follow-up assessment will provide some of the first evidence on predictors of the durability of placebo and context interventions.

NCT Number	NCT04646460
Lead Sponsor	Trustees of Dartmouth College
Conditions	Placebo Effect, Pain
Enrollment	120 participants
Start Date	2026-12-01
Primary Completion	2027-12-01 (estimated)
Study Completion	2028-12-01 (estimated)
Updated on ClinicalTrials.gov	2026-01-16