Reading in Two Colours at the Same Time

New brain imaging study reveals the structures that support colour synaesthesia

Milan, Italy, 9 March 2011 – The Nobel prize-winning physicist Richard Feynman once wrote in his autobiographical book (What do you care what other people think?): “When I see equations, I see letters in colors - I don’t know why […] And I wonder what the hell it must look like to the students.” This neurological phenomenon is known to psychologists as synaesthesia and Feynman’s experience of “seeing” the letters in colour was a specific form known today as “grapheme-colour” synaesthesia. What is perhaps most puzzling about this condition is that people actually claim to see two colours simultaneously when reading letters or numbers: the real colour of the ink (e.g. black) and an additional – synaesthetic – colour . Now a new study, published in the March 2011 issue of Elsevier’s Cortex ( has revealed the patterns of brain activity that allow some people to experience the sensation of “seeing” two colours at the same time.

A group of researchers in Norway used functional magnetic resonance imaging (fMRI) to investigate the brain activity patterns of two grapheme-colour synaesthetes, as they looked at letters written in different colours, presented on a screen while inside an MRI scanner. The participants had previously been asked to indicate the synaesthetic colours that they associated with given letters and were then presented with single letters whose physical colour sometimes corresponded to the synaesthetic colour and other times was clearly different.

Prof. Bruno Laeng from the University of Oslo, along with colleagues Kenneth Hugdahl and Karsten Specht from the University of Bergen, had reasoned that increasing the similarity between the physical and synaesthetic colours should affect the level of activity seen in areas of the brain known to be important for colour processing, and their results confirmed this expectation, revealing that the strength of the observed brain activity was correlated with the similarity of the colours.

The authors concluded that the same brain areas that support the conscious experience of colour also support the experience of synaesthetic colours, allowing the two to be “seen” at the same time. This supports the view that the phenomenon of colour synaesthesia is perceptual in nature.

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Notes to Editors:
The article is “The neural correlate of colour distances revealed with competing synaesthetic and real colours” by Bruno Laeng, Kenneth Hugdahl, Karsten Specht, and appears in Cortex, Volume 47, Issue 3 (March 2011), published by Elsevier in Italy. Full text of the article featured above is available to members of the media upon request. Please contact the Elsevier press office, To schedule an interview, contact Prof. Bruno Laeng,

About Cortex
Cortex is an international journal devoted to the study of cognition and of the relationship between the nervous system and mental processes, particularly as these are reflected in the behaviour of patients with acquired brain lesions, normal volunteers, children with typical and atypical development, and in the activation of brain regions and systems as recorded by functional neuroimaging techniques. It was founded in 1964 by Ennio De Renzi. The Editor in-chief of Cortex is Sergio Della Sala, Professor of Human Cognitive Neuroscience at the University of Edinburgh. Fax: 0131 6513230, e-mail: is available online at

About Elsevier
Elsevier is a global information analytics business that helps institutions and professionals progress science, advance healthcare and improve performance for the benefit of humanity. Elsevier provides digital solutions and tools in the areas of strategic research management, R&D performance, clinical decision support, and professional education; including ScienceDirect, Scopus, ClinicalKey and Sherpath. Elsevier publishes over 2,500 digitized journals, including The Lancet and Cell, more than 35,000 e-book titles and many iconic reference works, including Gray's Anatomy. Elsevier is part of RELX Group, a global provider of information and analytics for professionals and business customers across industries.

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