How Hypnosis Alters Brain Activity

A researcher from Stanford University in the United States, David Spiegel, took neuro-images (pictures of brain activity produced from brain scans) of individuals who had been hypnotized in an experiment which analyzed the effects of hypnosis on the physical brain.

In the experiment, the hypnotized individuals (who were all volunteers) were instructed by the experimenter to gaze at various objects. The objects were black and white; however, the volunteers who had been hypnotized were given the hypnotic suggestion that the black and white objects they were gazing at were coloured (or ‘coloured’, to use the American spelling of the word!)

Whilst the individuals were looking at the objects, having been given this hypnotic suggestion, the researchers took scans of their brain activity in order to produce the vital neuro-images which would show what was going on physically in their brains. The neuro-images (or brain scans) revealed that the areas of the brain which registered and processed colour were activated and had increased blood flow. In other words, the effect of the hypnotic suggestion on the volunteers’ brains led to them ‘seeing’ colours even though the objects were only black and white. It can be inferred from this that hypnotic suggestion can literally change how the brain works.

Daniel Spiegel, the lead researcher in this impressive study, said :

‘This is scientific evidence that something happens in the brain when people are hypnotized that does not happen under normal circumstances…there are tremendous medical implications for people being able to use hypnosis for such things as managing their own pain and anxiety…’


Below, I provide two, powerful examples that help to illustrate how hypnosis works :

I have written in other articles that have been published on this site about how hypnosis can help alleviate many adult psychological problems we may have connected to our experience of childhood trauma, such as anxiety, social anxiety, relationship problems, feelings associated with rejection and feelings relating to having felt unloved as a child and aches and pains that have a psychosomatic basis (see below).
In this article I will briefly outline two impressive scientific experiments that demonstrate how hypnosis works and just how powerful the effects of hypnosis can be :


The first experiment was carried out by the researcher of hypnotic phenomenon, Ernest Hilgard, and relates to how people’s perception of pain can be altered.

The experiment involved participants placing their arm in a container filled with ice-cold water.

The participants were split into 2 groups as follows:

GROUP 1: These participants had been hypnotized to increase their pain tolerance threshold.

GROUP 2: These participants formed the ‘control’ group (i.e. they had received no hypnosis to help them to withstand pain).


It was found that the participants in group 1 (who had received hypnosis) were able to keep their arms submerged in the ice-cold water for a significantly longer time period than those in group 2 (who had received no such hypnosis).


Due to the power of hypnosis to lower our perception of pain, hypnotherapy can be very effectively used, for example, to:

– reduce dental pain

– reduce the pain experienced during childbirth

– help alleviate chronic pain conditions (such as arthritis)


The second experiment of interest involved an examination of how our beliefs can affect our bodily responses in extremely surprising ways.

The experiment focused upon individuals who were allergic to a certain kind of plant leaf. Under hypnosis, they were given the posthypnotic suggestion that a leaf the experimenter was shortly going to rub on their hand was from the plant to which they were allergic.

In fact, though, this was intended deception; the leaf was completely harmless to them.

However, when this harmless leaf was rubbed on the back of their hands, because of the posthypnotic suggestion they actually developed an allergic reaction to it in the form of a rash, just as they would have done had the leaf been of the type to which they were actually were allergic.


Both these experiments, and the applications of hypnotherapy also detailed above, serve to indicate the power of the mind-body connection, and how hypnosis is able to enhance its effect.

David Hosier BSc(Hons); MSc; PGDE(FAHE).