Suggestibility and Hypnosis

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Biology 202

2006 First Web Paper

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Suggestibility and Hypnosis

Whitney McDonald

Recently an increasing amount of research has been conducted on the cognitive processes of the brain while under hypnosis. This research boom stems from questions regarding perception needing answers. It was found through trials and experiments addressing the mind under hypnosis that the body is able to perform and the mind is able to perceive things otherwise unperceivable or doable in the conscious state. In India a limb amputation was successfully performed while the person was under hypnosis and in this context hypnosis was used as the anesthesia (1). This and many other medical practices involving the use of hypnosis aroused the attention of neurobiologists. Hypnosis is when the brain is not thinking but rather experiencing without analysis. In this state the hypnotist is able to make suggestions to the hypnotized and their body and brain carry out these commands. This willingness to comply with suggestions is an effect of the conscious judgmental mind not being a factor of experience.

An experiment was conducted to compare physical strength in the conscious state to that of the hypnotized state. While conscious, men were asked to hold a brick out for as long as they could, which on average was about 5 minutes. These same men were then hypnotized and were able to hold the brick out for 15-20 minutes (2). This supports the idea that hypnosis crates a unique mindset that enables one to physically breach higher thresholds. Hypnosis is clearly able to influence physical ability but can hypnosis also alter understanding? As a result of many experiments involving color discernment, hypnosis can indeed alter understanding. A professor of clinical neuroscience at Colombia University performed tests investigating conflicts in the brain dealing with the perception of color. This experiment was called the "Stroop Effect"; for example, the word green may be presented in a blue color (1). The subjects would be asked to press the color corresponding to the color of the word (not the color associated with the meaning of the word); this would become a difficult task for all subjects because they would instinctively want to press the color meaning of the word rather than the color displayed, this is the "Stroop Effect". However while people were under hypnosis those that had less difficulty overcoming the Stroop Effect where the ones that performed well under hypnosis and effortlessly chose the color corresponding to the color of the word rather than the color meaning of the word. As evidence of this experiment it is clear that not only can hypnosis alter perception but not everyone is hypnotizable.

To categorize levels of ability to be hypnotized scientist classify people by levels of suggestibility. A person highly suggestible would be one to undergo hypnosis easily while one of lower suggestibility would be more resistant in submitting to hypnosis. Under the Stroop Effect experiment it was found that those who were highly literate had a hard time overcoming the Stroop Effect because of the need to interpret the meaning of the word instead of the color the word is being displayed (1); thus classifying those which did not overcome the Stroop Effect of having low suggestibility. Moreover, this may allude to the reason why there is a large gap between adults and children that are suggestible. It was found that 80-85% of children under age 12 are highly suggestible where as 10-15% of adults are highly suggestible (1) and this difference may be due to literacy levels. This supports the argument that the difference between the low and high suggestible people is not in inherent brain structures but the effect of development over time.

It turns out, from PET scan results; highly suggestible people use different regions of the brain than those of lower suggestibility. While conscious, subjects were asked to perceive color whether they saw color or not, brain activity was recorded and it was found that there was activity on only the right side of the brain. However while under hypnosis both sides of the brain revealed activity. "The left hemisphere...registered what people were told to see only when they were hypnotized the right registered what they were told to see whether or not they were hypnotized."(2) Moreover, because the left side of the brain deals with the logical reasoning mind and the right deals with the emotional illogical mind this supports the idea that while under hypnosis the left side of the brain is disassociated from logical thinking. To sense that there is in fact color where there may be a gray area reveals that hypnosis disassociates the left side of the brain from the senses or changes the senses by altering what exactly is being seen.

Furthermore, it was found that people who were classified to be highly suggestible used their cingulated gyrus region of the brain (2), more than those of low suggestibility. It is this region that connects the right and left sides of the brain and it may be because of the heightened activity in this area that highly suggestible people easily submit to hypnosis because hypnosis requires the use of both sides of their brain. More specifically, it was found that people of higher suggestibility have a larger rostrum, located in the corpus callosum, the rostrum is responsible to the allocation of attention (3). This alludes to further support why highly suggestible people easily submit to hypnosis because of their heightened ability to concentrate when being hypnotized and not be distracted by other thoughts or the surrounding as easily as low suggestible people.

These observations of a change in senses and heightened concentration while under hypnosis support the idea that hypnosis changes perception. Also if the perception of pain can be altered, as observed in the endurance experiment, then many other psychological problems such as addiction, depression, and insomnia can be solved as well. It now becomes clear through the analysis of effects of hypnosis and brain activity associated with hypnosis why 80-85% of children are highly hypnotizable and only 10-15% of adults are. Children would be able to submit to hypnosis with ease because they do not have as much experience as an adult to be analytical of the suggestions. Along these same lines children constantly move between imaginative play and reality, hence this would make the use of their cingulated gyrus of the brain heightened because they naturally use that region to switch between the illogical creative mind and the logical mathematical mind.

Although there are still many un-chartered issues in the area involving hypnosis and perception it is clear that hypnosis does change experience. Also, because experience shapes understanding, those that have the advantage of being highly suggestible can thus perceive life on a different level than those that are not; they can develop a control over involuntary functions of the brain. Accordingly, the possibility arises that through hypnosis the mind will be able to influence the immune system and other functions of the body to prevent ill health. Through the progression of the mind under hypnosis the mind will have more control over the body making many other chemical medications a thing of the past; the brain itself would develop the capacity to influence it's own body's behavior.


1)3,2,1: This is You're Brain Under Hypnosis,New York Science Times

2)Hypnosis found to alter the brain: Subjects see color where none exists.

3)Increased anterior corpus callosus size associated positively with hypnotizability and the ability to control pain.

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