Neural Mechanisms of Interpersonal Expectations on Negative Affect

Participants receive active tTIS, with two signals set at 2000 Hz and 2080 Hz, creating an 80 Hz interference beat targeting the anterior/mid-cingulate cortex (aMCC). Stimulation is delivered at 2 mA for 20 minutes. The stimulation is combined with a positive social placebo intervention delivered by the care provider. Participants complete three multimodal negative affect tasks (MNAT) before and after the stimulation.

Participants receive sham tTIS, using two identical 2000 Hz signals that produce no low-frequency interference. The device mimics active parameters (2 mA, 20 minutes) without delivering effective stimulation. The sham stimulation is paired with a positive social placebo intervention. Participants complete three MNAT tasks before and after the session.

Participants receive active tTIS (2000 Hz and 2080 Hz signals, 2 mA, 20 minutes) combined with a negative social placebo intervention (neutral or skeptical messaging about treatment efficacy). Participants complete three MNAT tasks before and after the stimulation.

Participants receive sham tTIS (identical 2000 Hz signals, mimicking active stimulation) combined with a negative social placebo intervention. Participants complete three MNAT tasks before and after the session.

Participants receive sham tTIS (brief 15-second stimulation followed by no current) paired with a positive social placebo intervention. Participants complete three MNAT tasks before and after the session.

Participants receive sham tTIS (brief 15-second stimulation, then no current) without any placebo intervention. Participants complete three MNAT tasks before and after the session.