It almost goes without saying that hypnosis is a very strange phenomenon. It is closely linked with the construct known as suggestibility, which simply refers to a person's capacity or propensity to believe in what s/he is being told, particularly by another person who is presented as an authority. Suggestibility, in turn, is likely related to a personality trait known as "dependence" that, in its pathological form, is called Dependent Personality Disorder. When conceived in pejorative terms, one might label such individuals as credulous, or gullible. However, it may be that this trait also corresponds to a capacity of the human mind/brain to use the power of thought to alter brain function in adaptive ways. We know, for example, that the use of self-suggestions (self-hypnosis), visualization, and mental rehearsal, can powerfully alter mood, and can change behavioral functioning, as well. Many athletes have benefited from these methods, and psychotherapists often use them.
One of my favorite mind science blogs, Mind Hacks, has a new entry, describing a fascinating study involving abnormal color perception, or synesthesia. People who have a form of synesthesia experience or perceive colors when they see or think about numbers. It turns out that some people who do not normally have synesthesia can be hypnotically induced to perceive colors with numbers in the same way; moreover, PET scans confirmed, in this study, that the subjects' brains (the visual cortex) were responding as if colors were actually present. In other words, the hypnotic suggestion was causing changes consistent with actual, and not merely claimed, perception of the visual phenomenon of seeing color. So, it is not as if the hypnotized subjects were simply conned into falsely believing that they were seeing colors; so far as their brains were concerned, they WERE seeing colors.
The therapeutic implications of this study are clear: what we tell ourselves becomes the truth, so far as our brains are concerned. The placebo effect is an example of this type of phenomenon. But we also can see how it may be that even the simplest forms of self-suggestion, such as telling myself "I can do this!" when I am facing a difficult task, can indeed be a significantly helpful tactic. The messages that our minds provide to our brains create conditions within the brain that prepare us for actions in accordance with the messages; and these actions may be quite novel, difficult, and of great value. These findings are consistent with many practices that have been used for thousands of years within religious traditions, as well: visualization and compassion practices are well-known, and likely have strong impacts on the functioning of our brains, which translates into (and are experienced as) change in our thoughts, emotions, and behavior. The impact of compassion practices (metta, or loving-kindness meditation) on such diverse outcomes as perceptions of others, and the way our immune system responds to injury (the inflammatory response), are currently being studied.
Can everyone benefit from these practices? We know that there are individual differences along a continuum of "hypnotizability" or "suggestibility." It is not known whether people can engage in practices that will increase their capacity to respond to suggestion (self-suggestions, or suggestions provided by others). That's a question that someone should be working on!
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