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May 2024

New study casts light on synaesthesia among signed language users

Many synaesthetes experience colours when viewing letters or digits but a new research study involving academics from UCL, has for the first time, documented a similar phenomenon among users of signed languages.

Synaesthesia is a phenomenon in which perceptual experiences, such as colours, tastes, or smells are elicited by stimuli that are not usually associated with such experiences such as letters or sounds. For example, in the most common form of synaesthesia, known as ‘grapheme → colour synaesthesia’, letters or numbers are perceived as coloured. People who report a lifelong history of such experiences are known as ‘synaesthetes’ and it’s a condition that affects around 4% of the population.

While there has been a considerable amount of documented research into synaesthesia within reading, writing and speech, little is known as to whether the condition affects users of signed languages, and whether there is a transfer between written language and fingerspelling. However, a new study recently published in the journal, Neurocase, has for the first time documented an equivalent synaesthesia amongst signed language users, with colours induced by manual fingerspelled letters and number signs.

Researchers, Dr. Joanna Atkinson and Prof Bencie Woll, from the Deafness, Cognition and Language Research Centre (DCAL), University College London, have collaborated with academics, Jamie Ward from the University of Sussex and David Eagleman of Baylor College of Medicine in Texas and presenter of BBC series ‘The Brain with David Eagleman’, to demonstrate that colour associations may also transfer from writing and fingerspelling systems but also this can occur within signed language based on perceptual similarity or articulatory features such as handshape.
Commenting on the publication, Dr Atkinson, said:

“The results from this collaborative project which has brought together world experts in synaesthesia with world experts in sign language research.

“Working with a mixed study cohort of hearing and signed language users – both of British Signed Language (BSL) and American Signed Language (ASL) – we discovered evidence that manual alphabet/numeral sign → colour synaesthesia exists within second-language users of two different signed languages, ASL and BSL.

“These findings fit with the notion that for most second-language learners, the transfer of colour into this system is primarily determined by conceptual meaning based on their first language but the colours can also be influenced by perceptual properties of the signs or fingerspelled letters themselves.

“This study also underlines the importance of broadening research to include signed languages because this casts new light on the mechanisms underpinning synaesthesia in general.”

The full article can be found here: