Colour my numbers

New study suggests learning is a key part of synaesthesia

Milan, Italy, 17 December 2009 - For as many as 1 in 20 people, everyday experiences can elicit extra-ordinary associated sensations. The condition is known as synaesthesia and the most common form involves “seeing” colours when reading words and numbers. Many previous studies have shown that the brains of people who experience this phenomenon are different from those who do not and, in a new study reported in the February 2010 issue of  Cortex, published by Elsevier, researchers from the University of Padova, Italy, have discovered that learning may also play an important role in synaesthesia and can lead to synaesthetic behaviour even when the person is not consciously aware of the experience.

Dr Ilaria Berteletti and colleagues tested an Italian synaesthete using a classic test, in which the participant was shown a series of numbers presented in different ink colours and asked to name those colours. A synaesthete for whom the number 2 is red will find it more difficult to name the ink colour of a green 2 than if the number is presented in red ink and will take longer to respond. This slowing of response is generally taken as evidence that synaesthetic experiences are real and automatic.

As predicted, the participant in this study was slower to name the colours of the presented Arabic digits when they did not match the colours that he had reported "seeing". Strikingly, the same slowing was observed when the numbers were presented as dots, such as dice patterns, even though the participant denied seeing any colours for these types of stimuli. The results suggest that the mere concept of a number, regardless of how it was presented visually (as an Arabic digit or pattern of dots), was enough to produce the marker of synaesthetic behaviour, even when the participant was not conscious of experiencing synaesthesia.

According to co-author Dr Edward Hubbard, "a lifetime of synaesthetic experiences may lead to the creation of learned associations between different classes of stimuli" and that "conscious awareness of these associations is not necessary for them to affect behaviour".

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Notes to Editors:
The article is “Implicit versus explicit interference effects in a number-color synesthete” by Ilaria Berteletti, Edward M. Hubbard and Marco Zorzi and appears in Cortex, Volume 46, Issue 2 (February 2010), 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, newsroom@elsevier.com. To schedule an interview, contact Dr. Edward Hubbard, edhubbard@gmail.com.

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: cortex@ed.ac.uk. Cortex is available online at http://www.sciencedirect.com/science/journal/00109452.

About Elsevier

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