blue brain

I get it. I understand why people are cynical about hypnosis. In my last blog I discussed stage hypnosis, and the tricks used to convince an audience. Hypnotising dogs on Britain’s Got Talent don’t help its image and the portrayal of hypnosis in films and television usually just confirms people’s suspicions that it is all a con.

I’ll admit that when I first started my training 5 years ago, even though I entered with an open mind, I still had nagging doubts. During the initial training sessions as the tutor talked about “altered states of consciousness” and the brain entering an “alpha” brain state (now proven to be wrong anyway), a little bit of me still thought it all sounded a bit dodgy.

As time went on and I gained more experience working with clients I started to see the benefits that hypnosis had on individuals. Clients who came to see me who were overwhelmed by their feelings and emotions were able, through hypnosis, to take back control of their life. They were able to gain a better perspective about their problems and very quickly became more optimistic about the future. Unhelpful habits that they had developed became easier to let go of and replace with healthier behaviours.

I still don’t know if hypnosis is a unique “state”. Even recent research using the most high tech brain scanning equipment can’t categorically prove that it is either. The truth is that hypnosis isn’t a unitary state anyway, but is very task specific. Therefore, you would expect to see differences between a person who is hypnotised and instructed to relax deeply compared to one who is asked to hallucinate (for example to imagine that they see an object in front of them).

However, gathered below are 3 studies which throw up some interesting results. They don’t prove conclusively that hypnosis exists but go some way to showing that it is worthy of further research and a reappraisal from the media and the general public.

Hypnotic inductions can change affect activity in the brain

It might come as a surprise, but when we are at rest, parts of our brain actually become more active. The default mode network, as it is called, includes large areas of the brain which paradoxically are more active when we’re at rest compared with when we’re engaged in a taxing, externally focused task.

As part of one experiment, researchers assessed brain activity of participants while resting in an fMRI scanner and also while engaged in visual tasks, both in and out of hypnosis. Participants, who were already identified as highly suggestible, whilst in hypnosis showed decreased brain activity in the parts of the default mode circuit. In low suggestible participants, hypnotic inductions produced no detectable changes in these regions, but instead deactivated areas involved in alertness. The findings indicated that hypnotic inductions create a distinctive and unique pattern of brain activation in highly suggestible subjects. Interestingly, the parts of the brain that showed decreased activity in the hypnotised participants included those responsible for daydreaming and letting the mind wander. This might support the idea that hypnosis creates a heightened increase in focused attention.

Hypnosis changes colour perceptions in the brain

A study conducted at Harvard University was designed to show whether hypnosis could affect colour perceptions. Using a positron emission tomography (PET) scan, eight highly suggestible subjects were asked, both in and out of hypnosis, to view a colourful Mondrian style pattern, in different ways:

  • The original version in colour
  • A similar grayscale version in colour
  • The colour version as grayscale
  • The grayscale version as grayscale

When subjects were hypnotised, parts of the brain responsible for colour perception were activated when they were asked to perceive colour, whether they were actually shown the colour or the grayscale version. However, those same brain regions had decreased activation when subjects were told to see grayscale, whether they were actually shown the colour or grayscale version. In other words the brain responded “as if” they were seeing a colour image (whether or not they were in reality), rather than just imagining they were. In the same way, they responded “as if” the image was grayscale even if it was really in colour. The conclusion of the researchers was that the subjective changes that the subjects experienced were reflected by the changes in the brain.

Hypnotic suggestions eliminate Stroop effect

You may have already seen the classic experiment into the Stroop Effect. A list of random words for colours are presented. Each word is printed in the same colour as the word it represents. The participant is asked to read out the words and are timed doing so. A second list of words is then produced, but each word is printed in a different colour to the one it represents. Upon the second attempt to name the words, most participants will take longer to name the words (you can try the experiment here ).

The Stroop Effect is a demonstration of interference in the reaction time of a task. It’s difficult to name the colour because our autonomic processes want us to read the words, rather than naming the colour. However, if the words were in a different language, such as Polish, you would have no problem naming the colour because the words have no meaning to you (unless you speak Polish).

In a study in 2002, a group of 16 high suggestible subjects as well as a group of 16 lower suggestible subjects were given hypnotic suggestions that they only attend to the font colour and ignore the meaning of the word. The results of the experiment were that posthypnotic suggestions eliminated Stroop interference for highly suggestible subjects. Studies using an fMRI showed changes in the brain including  lower activation in the anterior cingulate cortex, an area involved in resolving conflict and competing demands. There was also a reduction in activity in the visual cortex, which is important for recognising words.



Hypnotic induction decreases anterior default mode activity (2009) 

Hypnotic Visual Illusion Alters Colour Processing in the Brain (2000) 

Hypnotic suggestion and the modulation of Stroop interference (2000) 


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