Abnormal results can occur in instances where amateurs, who know the fundamentals of hypnosis, entice friends to become their experimental subjects. Their lack of full understanding can lead to immediate consequences, which can linger for some time after the event. If, for example, the amateur plants the suggestion that the subject is being bitten by mosquitoes, the subject would naturally scratch where the bites were perceived. When awakened from the trance, if the amateur forgets to remove the suggestion, the subject will continue the behavior. Left unchecked, the behavior could land the subject in a physician's office in an attempt to stop the itching and scratching cycle. If the physician is astute enough to question the genesis of the behavior and hypnosis is used to remove the suggestion, the subject may experience long-term negative emotional distress and anger upon understanding exactly what happened. The lack of full understanding, complete training, and supervised experience on the part of the amateur places the subject at risk.
Hypnosis, an enhanced state of inner focus, can be an effective tool for improving a range of symptoms, including those related to mood and learning. The ADHD drug methylphenidate (Concerta, Ritalin) has been shown to increase hypnotizability in a sample of patients with ADHD and thus may enable patients to benefit from adding hypnosis to their treatment regimens.
Gruzelier and his colleagues studied brain activity using an fMRI while subjects completed a standard cognitive exercise, called the Stroop task. The team screened subjects before the study and chose 12 that were highly susceptible to hypnosis and 12 with low susceptibility. They all completed the task in the fMRI under normal conditions and then again under hypnosis. Throughout the study, both groups were consistent in their task results, achieving similar scores regardless of their mental state. During their first task session, before hypnosis, there were no significant differences in brain activity between the groups. But under hypnosis, Gruzelier found that the highly susceptible subjects showed significantly more brain activity in the anterior cingulate gyrus than the weakly susceptible subjects. This area of the brain has been shown to respond to errors and evaluate emotional outcomes. The highly susceptible group also showed much greater brain activity on the left side of the prefrontal cortex than the weakly susceptible group. This is an area involved with higher level cognitive processing and behaviour.
“That study changed the whole landscape,” said Dave Patterson, a psychologist at the University of Washington in Seattle, who has been using hypnosis since the 1980s to help burn victims withstand the intense pain that comes with the necessary but excruciating bandage removal and wound cleaning. Since the ’90s, other well-designed, controlled studies have been published showing similar changes in brain activity. In another slightly trippy example, researchers suggested to people in a hypnotic state that the vibrant primary colors found in paintings by Piet Mondrian were actually shades of gray. “Brain-scan results of these participants showed altered activity in fusiform regions involved in color processing,” notes psychologist Christian Jarrett.
The first neuropsychological theory of hypnotic suggestion was introduced early by James Braid who adopted his friend and colleague William Carpenter's theory of the ideo-motor reflex response to account for the phenomenon of hypnotism. Carpenter had observed from close examination of everyday experience that, under certain circumstances, the mere idea of a muscular movement could be sufficient to produce a reflexive, or automatic, contraction or movement of the muscles involved, albeit in a very small degree. Braid extended Carpenter's theory to encompass the observation that a wide variety of bodily responses besides muscular movement can be thus affected, for example, the idea of sucking a lemon can automatically stimulate salivation, a secretory response. Braid, therefore, adopted the term "ideo-dynamic", meaning "by the power of an idea", to explain a broad range of "psycho-physiological" (mind–body) phenomena. Braid coined the term "mono-ideodynamic" to refer to the theory that hypnotism operates by concentrating attention on a single idea in order to amplify the ideo-dynamic reflex response. Variations of the basic ideo-motor, or ideo-dynamic, theory of suggestion have continued to exercise considerable influence over subsequent theories of hypnosis, including those of Clark L. Hull, Hans Eysenck, and Ernest Rossi. It should be noted that in Victorian psychology the word "idea" encompasses any mental representation, including mental imagery, memories, etc.
Braid later acknowledged that the hypnotic induction technique was not necessary in every case, and subsequent researchers have generally found that on average it contributes less than previously expected to the effect of hypnotic suggestions. Variations and alternatives to the original hypnotic induction techniques were subsequently developed. However, this method is still considered authoritative. In 1941, Robert White wrote: "It can be safely stated that nine out of ten hypnotic techniques call for reclining posture, muscular relaxation, and optical fixation followed by eye closure."
Hypnotherapy is guided hypnosis, or a trance-like state of focus and concentration achieved with the help of a clinical hypnotherapist. This trance-like state is similar to being completely absorbed in a book, movie, music, or even one's own thoughts or meditations. In this state, clients can turn their attention completely inward to find and utilize the natural resources deep within themselves that can help them make changes or regain control in certain areas of their life.