From the article: In the study, 112 healthy volunteers between the ages of 18 and 40 took part. Their guilt was measured at the beginning using questionnaires including the state shame and guilt scale (SSGS). This questionnaire asks people whether they feel remorse or bad about something they’ve done. Next, the participants did an exercise intended to make them feel more guilty. The exercise involved writing a story about a time they had treated someone they loved unfairly.

The participants were then divided into three groups. One group received a “deceptive placebo”: a blue pill they were told was a real drug. Specifically, they were told that the pill contained phytopharmacon, a substance designed to reduce the feeling of guilt by making whoever took it feel calmer.

Another group received an “open-label placebo” – the same blue pill, but this group was told it was a placebo. They were told that placebos benefit many people through mind-body self-healing mechanisms.

The third group did not receive any treatment at all. This was the “control” group.

After getting the treatment, the guilty feelings were measured using the same questionnaires to see whether the deceptive placebo or open-label placebo was more effective than no treatment.