The Neurological Magnificence of the Human Brain

This area of cognitive neuroscience research into hypnosis is still relatively new but is a fascinating one. No doubt as time goes on, our understanding of the special nature of hypnosis will be elucidated more and more.

The Brain in Neutral Hypnosis

According to Dr. David Oakley and Dr. Peter Halligan of University College London and Cardiff University respectively, an important area of research is identification of the neurological changes in the brain when a person is hypnotized, before any hypnotic suggestions are given. They define this state of neutral hypnosis as “a change in baseline mental activity after an induction procedure and typically experienced at the subjective level as an increase in absorption, focused attention, disattention to extraneous stimuli and a reduction in spontaneous thought.”

In their paper titled “Hypnotic Suggestion and Cognitive Neuroscience,” they refer to three different studies designed to establish possible neurological differences between a state of no hypnosis and neutral hypnosis. Using PET scanning technology, one study found, in contrast to a state of no hypnosis, co-ordinated activity between several areas of the brain including the brainstem, the anterior cingulate cortex, the right inferior frontal gyrus and the right inferior parietal lobule.

Another study found evidence of brain activity commensurate with a reduction in conceptual spontaneous thought, whilst, using EEG readings, a third also found disruption in normal communication between cognitive systems.

Whilst Oakley and Halligan concluded that more research is needed, they indicate that neurological changes do appear to occur in the neutral hypnotic state. The data points to changes in the way different cognitive systems of the brain communicate in neutral hypnosis and may account for the experience subjects have of mental absorption, reduction in spontaneous thought and sense of detachment.

The Brain and Post Hypnotic Suggestion

In recent years, Dr. Amir Raz of McGill University in Montreal has carried out research to establish what happens in the brain following post hypnotic suggestion. A post hypnotic suggestion is one given to a subject in hypnosis that is intended to be acted upon at a later date. Dr. Raz decided to base his experiment around the Stroop Effect.

The Stroop Effect was defined in the 1930s. The Stroop test involves presenting the subject with words that are the names of colours. However, the word itself is coloured in a different colour to that of its name. Thus, red may be coloured green and blue may be coloured yellow and so on. This test presents conflict for the subject because the act of reading is so ingrained. To see the word ‘red’ yet be required to report its colour usually leads to errors and slower reaction times.

Raz selected highly hypnotizable subjects according to the Harvard and Stanford scales and a control group of what he called ‘resistant’ subjects. They were given the post hypnotic suggestion that when they entered a brain scanner and heard his voice some days later, the words they saw before them would appear as nonsense and they were only to report on the colours of the words.

After carrying out the experiment, Raz reported that those he had identified as highly hypnotizable did indeed see the words as scrambled and reported the colours without hesitation. Those subjects identified as “resistant” saw the words as they were written and exhibited the Stroop Effect.

On comparing brain scans, Raz found that in the first group, the area of the brain responsible for decoding written words was suppressed as was the activity of the anterior cingulate cortex one of whose functions is conflict resolution. This did not occur in the second group.


Cell Press Hypnotic Suggestion and Cognitive Neuroscience David A Oakley and Peter W. Halligan, American Journal of Clinical Hypnosis Interview with Amir Raz PhD, July 14, 2005.