Hypnosis is the process of artificially putting a person into a sleep-like state, making them more open to the power of suggestion. It is usually regarded as an “alternative” kind of practice. Most medical doctors and mainstream medical organizations do not recommend it. Though we sometimes hear stories about people quitting smoking or overcoming phobias due to hypnotherapy, there is a lack of reliable evidence for efficacy. Besides this, hypnotherapy is notoriously difficult to study in a controlled setting. As R. Barker Bausell put it:
Hypnosis and the placebo effect are “so heavily reliant upon the effects of suggestion and belief that it would be hard to imagine how a credible placebo control could ever be devised for a hypnotism study”.
These complications aside, I did find an interesting study on hypnotherapy and soccer wall-volley performance: Assessing the immediate and maintained effects of hypnosis on self-efficacy and soccer wall-volley performance:
This study evaluated the effects of hypnosis on self-efficacy and soccer performance. Fifty-nine collegiate soccer players were randomly allocated to either a hypnosis (n = 30) or video attention-control group (n = 29). A pretest-posttest design with an additional 4-week follow-up was used. Self-efficacy was measured via a task-specific questionnaire comprising 10 items relating to good performance on a soccer wall-volley task. The hypnotic intervention comprised three sessions using ego-strengthening suggestions. The control group watched edited videos of professional soccer games. Results indicated that, following the intervention, the hypnosis group were more efficacious and performed better than the control group. These differences were also seen at the 4-week follow-up stage. Although changes in self-efficacy were associated with changes in performance, the effect of hypnosis on performance was not mediated by changes in self-efficacy. The study demonstrates that hypnosis can be used to enhance and maintain self-efficacy and soccer wall-volley performance.
So it does appear to have “worked”, though the “video attention” control group seems like a very strange, probably unsatisfactory method for controlling. Again, it is very difficult to placebo control for hypnosis since hypnosis is all about suggestion and so are placebos. I don’t think anyone argues against the benefits of “ego strengthening” or thinking positive, though this can be done without hypnosis(though overconfidence can be a problem for some). All we may be seeing here with this study are the generic benefits of positive thinking, not anything specific from the hypnosis.
It would be great if researchers could figure out a better way to study this. In the mean time, I’ll try to think more positively.