UK Synaesthesia Association
what is synaesthesia?
What colour is the letter "A"? What does the number '1" taste of? Does listening to music, speaking or eating food produce colours, shape or texture? For most people, questions such as these will either yield a look of bewilderment or an emphatic "No!"

Synaesthesia is often described as a joining of the senses. Sensations in one modality (e.g. hearing) produce sensations in another modality (e.g. colour) as well as it's own. Synaesthetic experiences are often driven by symbolic rather than sensory representations, such as letters, numbers and words. It is also often experienced in the absence of external sensory input, such as one's "inner speech".

Historical Background

"I will simply remark - First, that the existence of the colour associations with sound is fully as remarkable as that of the Number-Form with numbers. Secondly, that the vowel sounds chiefly evoke them. Thirdly, that the seers are invariably most minute in their description of the precise tint and hue of the colours. They are never satisfied, for instance, with saying "blue", but will take a great deal of trouble to express or to match the particular blue they mean. Fourthly, that no two people agree, or hardly ever do so, as to the colour they associate with the same sound. Lastly that the tendency is very hereditary. "

Sir Francis Galton (1883) "Inquiries into Human Faculty."


Synaesthesia has been a topic of interest to Psychologists ever since psychology emerged as a discipline in its own right in the late nineteenth century. It is an intriguing phenomenon because it challenges the tacit assumption that other people's perceptual experiences of the world are the same as our own. Philosophers may lose sleep over my experience of green is the same as your experience of green, but people on the street do not. This is because we can use language as a common currency to agree upon our experiences.

But what are we to make of someone claiming that the letter "A" is red, when most of us do not experience this at all? Well, one solution is to dismiss subjective reports as having no place in science or psychology. The Behaviourist movement did just this, and the number of publications devoted to synaesthesia plummeted in the mid-20th Century as a direct result.

However, times have changed and understanding of how the brain creates our conscious experience of the world is a hot topic. Synaesthesia research is enjoying its Renaissance. If you are interested in contributing to this research why not fill in our online questionnaire here...?

In the Mind of a Synaesthete

What is it like to have synaesthesia? The synaesthete, Pat Duffy, puts it this way: "Other people don't see what we see and they're not convinced that we see it ourselves. But what each of us sees is the reality we know. I am no more at liberty to change the white colour of the letter 'O' than I am to change its circular shape: for me, the one is as much an attribute of the letter as the other" (Duffy, 2001) Pat's synaesthetic alphabet is shown below, as painted by the artist Carol Steen, together with her synaesthetic calendar 'form'.

Every synaesthete has their own palette of colours and often different types of trigger. Carol is a synaesthete herself and describes here experience thus: "There have been times when I have had one sensation such as toothache and observed the color of the pain, its taste and smell. All these synaesthetic perceptions are aspects of one overall experience. I perceive them as related in the same whay that windows, a door and front steps combine to become the image of a house."

Carol uses here synaesthetic experiences as inspiration for her artwork. This painting shows the colour images that were evoked during an accupuncture session. Her descriptions imply a richness of colours, movement and texture: "Lying there, I watched the black background become pierced by a bright red colour that began to form in the middle of the rich velvet blackness. The red began as a small dot of colour and grew quite large rather quickly, chasing much of the blackness away. I saw green shapes appear in the midst of the red color and move around the red and black fields."

As a synaesthetic artist, Carol is in good company. Other artists with synaesthesia include the painter David Hockney, the composer Olivier Messiaen, and the writer Vladimir Nabokov.