Post hypnotic suggestion and the Stroop effect

Over the last two decades the use of hypnosis and post-hypnotic suggestion has moved from the realm of parapsychology into the mainstream of cognitive neuroscience research into consciousness. Former Wellcome Trust funded post-doc Ben Parris (University of Bournemouth) has developed a particular interest in how “cognitive control” mechanisms can be modified by post-hypnotic suggestion. The process of inducing an hyponotic suggestion in the lab involves reading out a simple script to volunteers who have consented to be hypnotised and have been identified to be susceptible to hypnosis through a pre-screening procedure. 

  Our most recent paper together with Zoltan Dienes (Universityof Sussex), just published in the Journal of Experimental Psychology: Human Perception and Performance, examined how hypnotic suggestion affected performance in the Stroop task. In the classic Stroop task participants have to respond to the ink colour of a word which can be in conflict with the word itself e.g BLUE. Normally people respond more slowly when the word and colour are in conflict with each other, but previous studies have suggested that the effect can be abolished by implanting the suggestion that words are printed in incomprehensible characters from a foreign language (the “word blindness” suggestion)(Raz et al. 2002).

  Ben was only partially able to replicate the original results and showed that it was only under certain conditions that the Stroop effect was abolished. Specifically when the stimuli were presented rapidly such that there was only 500ms between the last response and the next word being shown. Subjects who did not receive the word blindness suggestion still showed a strong Stroop effect even at the short response stimulus intervals.

   The finding tells us about the level at which the hypnosis effect influences control over mental processes. In the case of the Stroop effect, word blindness is “activated” in a reactive way by the onset of a word and participants do not always exert sustained effort to maintain the word blindness suggestion. How post-hypnotic suggestions affect the brain’s perceptual and action control centres remains an ongoing question, but together with previous work, the new results offer some intriguing clues. They also confirm that hypnotic suggestion is a serious tool for the scientific study of mental processes and consciousness.


Parris BA, Dienes Z, Hodgson TL (2012) Temporal Constraints of the Word Blindess Posthypnotic Suggestion on Stroop Task Performance. Journal of Experimental Psychology: Human Perception and Performance. Advance online publication.

Raz A et al. (2002) Suggestion reduces the Stroop effect. Psychological Science, 17, 91-95.

OAKLEY, D. A. & HALLIGAN, P. W. (2009). Hypnotic suggestion and cognitive neuroscience. Trends in Cognitive Sciences, 13, 6, 264- 270

Eye Movements Now On U-Tube

I have uploaded a number of eye movement recordings taken from various projects I have been involved with over the years using the Eyelink eye tracking system, to a dedicated U-tube channel! Anyone can browse, ask questions or comment on the videos and I have given links to the relevant publications where available. I’ll be uploading some more soon but take a look here:

The School of Psychology has recently just taken delivery of the next generation of Eyelink system the Eyelink 1000

Most of the videos on the U-tube site were taken with the Eyelink 2. The Eyelink 1000 allows for “heads free” tracking at high spatial and temporal resolution. We plan to use it for testing in neurological patients as well as at the forthcoming Summer Scientist research day

Visual Neuroscience and Specialist Education

We have been invited to submit a full version of our Knowledge Transfer Partnership proposal with the West of England School and College for Young People with Little or No Sight (

The project aims to bring knowledge of visual neuroscience into specialist visual impairment education, where a large number of children have visual problems that are of a neurological origin (rather than arising from disorders of the eye). This innovative partnership with the University of Lincoln School of Psychology and School of Computer Science will also develop a visual rehabilitation “game”: A fun computer based tool which will benefit children with visual field loss (i.e. “holes” in their vision due to damage to the brains visual pathways). The game will use principles derived from existing programmes used in adults with visual field loss, in which patients have to search for difficult to find objects on a computer screen (a so-called “visual search” task), but modified to make them more interesting and fun for children and to maximise the efficiency of learning.

I am personally excited about the prospect of this project coming to fruition and it represents a great opportunity to generat impact from knowledge derived from neuroscience and psychology in order to put it into practice in specialist education.

References and relevant links

Pambakian ALM, Mannan SK, Hodgson TL & Kennard C (2004) Saccadic visual search training: a treatment for patients with homonymous hemianopia Journal Of Neurology Neurosurgery And Psychiatry  75(10): 1443-1448.

fMRI research on eating disorders – the role of the insula?

This week I will be visiting the Regional Eating Disorders Service at Ulleval Hospital University of Oslo:

Clinical psychologist and current PhD student Ian Frampton has been carrying out research based at the unit using fMRI to determine if individuals with anorexia nervosa have abnormal patterns of activity in the insula cortex of the brain. He is examining patterns of activity in patients and controls while they perform cognitive tasks that tax working memory, executive control and attention, some of which are specially modified to use materials which might activate body image or food reward processing systems.

 Historically, the insula cortex was known to play an important role in advanced processing neural signals coming from the gut (some people have even called it the “hippocampus of the gut”), but more recently it is perhaps more widely known for its involvement in emotion and socio-economic decision making  (see earlier post  on our coordination game fMRI study).  Ians research spans  the two fields, so I am really pleased to be involved with it and very much looking forward seeing his latest imaging results! 

The research has the promise to provide better techniques for assessing and diagnosing eating disorders, as well as better fundamental understanding of the neural, cognitive and emotional mechanisms involved in anorexia and related conditions.

PhD Research Opportunities

A fully funded studentship is available in the School of Psychology, University of Lincoln

Applicants are encouraged from all areas of psychology, but please contact me in particular if you are interested in eye movement control and cognition in Parkinsons disease and focal brain damage.  Another potential project for a PhD researcher would be the development of saccadic orienting to socio-biological cues in children (see

The School of Psychology is well equiped for Cognitive Neuroscience research with a full EEG / ERP recording system, Tobii and soon to arrive Eyelink 1000 Eyetracker as well  a Transcranial Magentic Stimulation system. Opportunities for carrying out fMRI based research also exist via several close by research centres.

A link to the School website including research groups, staff interests and lab pages is here:

Further particulars of the PhD studentship opportunities in the College of Social Sciences including details of how to apply are available via: