“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 post is about the placebo response and related phenomena. This is the seventh post on this book.
This post is about hypnosis. During the late 50s and early 60s researchers at Stanford and Harvard came up with 12-step scales to quantify how suggestible to hypnosis someone is. Their research led these researchers to conclude that hypnotic susceptibility is a fixed trait. Susceptibility to hypnosis doesn’t change much from late adolescence until death. The most spectacular forms of hypnosis work only on the most hypnotizable 10% or so of the population. Another 10% do not respond to hypnosis at all, and 80% fall somewhere in between.
A Canadian psychologist Pierre Rainville successfully hypnotized one group not to feel any pain from hot water poured on their hands and another group to believe that they could feel pain but that it would not bother them. Their brains were scanned with positron emission tomography (PET) and found two very different neural reactions to pain. This suggested that the sensation of pain and the emotions associated with it have separate triggers as well a how crucial emotion is to our experience of pain. There is also neurological evidence that there are two different pathways for pain. One dealing with the response to the pain itself, and the second to the interpretation of the pain. It is this latter response that characterized chronic pain. See the previous healthy memory blog posts “Pain and the Second Dart,” “To Treat Chronic Pain, Look to the Brain Not Body,” and “Controlling Pain in Our Minds.”
Rainville’s work indicates that hypnosis often involves parts of the brain associated with attention, emotion regulation, and pain. People seem to be wired differently for hypnosis, and that this doesn’t change much over the course of our lives. Research has also shown that the capacity to be hypnotized is not tied to intelligence or willpower.
Some tend to think of hypnosis as being another placebo. The consensus is that they are not related. Hypnotic susceptibility remains relatively stable throughout one’s life, whereas placebo responsiveness can change from day to day. And the drug naloxone, which is effective at blocking placebo responses doesn’t block hypnosis. So although they are not the same, they both tap into a deep force in the brain: expectation.
Psychologist Marcel Kinsbourne says, “There is a wave of bottom-up information coming up from the external world, up into your brain. There is a wave of information coming from the cortex that consists of your evaluations, your beliefs, your expectations. Consciousness is these two waves hitting each other. It’s a collision. And this is where hypnosis and placebos do their work.”