“Suggestible You” is the title of a book by Erik Vance. The subtitle is “The Curious Science of Your Brain’s Ability to Deceive, Transform, and Heal. This book is about the placebo response and related phenomena. This is the fourth post on this book.
An important question is whether there is a way to enhance the placebo effect, or even make it permanent. In 2015 Karin Jensen, a placebo researcher at Harvard, published an experiment that showed how our brains can self-medicate even when we are not paying attention. She set up a two phase experiment in which subjects wore a painful heat pad that flared up whenever they saw a picture of a certain face and died down when they saw another, similar face. The brain learns that one face is bad and the other face is good.
In the next phase, after the relationship had been ingrained in the participant, she turned the heat to somewhere in the middle. This time she showed the picture for only a fraction of a second, so the participants could barely see the face. The subconscious mind could spot the difference, but the conscious mind could not. Nevertheless the participants continued to feel pain with the bad face, and less pain with the good face, even when they could not consciously distinguish the faces. With enough practice, people can unconsciously trigger the placebo effect with the flash of one face, even though their conscious mind has no idea its happening.
The placebo effect can also be altered by peer pressure. One of Wager’s students, Leonie Koban, set up an experiment in which people rated various levels of heat pain applied to their arms by a metal pad. After gauging each person’s pain threshold, she asked them to rate how much pain they expected to feel before she applied it, but with one additional crucial element. They would also be able to see how other people had rated the same pain. These previous reports of pain were totally made up. Still, people who felt a strong pain rated it lower if that’s what they thought others had done. And people who were told others had felt a lot of pain rated the pain highly even if it was mild. This peer pressure placebo effect was twice as strong as the normal placebo effect! As a check, Koban recorded their skin conductance, which is a physiological response to pain. On the basis of skin conductance it was impossible to differentiate from a genuine experience.
It seems that people are programmed with a preexisting need to go with the herd. People quickly tapped into a more powerful placebo response than if they had spent hours conditioning themselves. So someone else’s opinion is not only powerful, but it can be more powerful than your experience and even more powerful than repeated conditioning. So we are hardwired to follow other people’s opinions.
Vance suggests that there might be some biochemistry involved in this interaction. Luana did an experiment similar to the one reported in Suggestible You 2 in which a green screen induced a placebo effect. The participants in this new experiment were given a dose of vasopressin before the green screen experiment. In yet another experiment the participants were given a dose of a related hormone, oxytocin. These drugs greatly enhanced the placebo effect. These hormones play a large role in social interactions among people. Vasopressin seems to regulate social communication and conciliatory behavior. Oxytocin seems to be involved in experiences of empathy, trust, and social learning. So the same chemicals that draw us together as humans and allow us to work together can also boost the placebo response altogether.