This is not a disorder; these people do not suffer. Australian PhD student, Anina Rich considers these people to have an unusual gift. As part of a small University of Melbourne team, Rich is one of the few people in the world studying the phenomenon of Synaethesia, a condition that raises more questions than answers and generally has researchers baffled.
Rich is giving a plenary paper this week at the ninth annual meeting of the Cognitive Neuroscience Society in San Francisco, USA about her latest research from the preliminary analysis of brain images of synaesthetes. It is one of the first objective analyses of the condition and their results have begun to reveal the secrets of how the brain of synaesthetes function.
The University of Melbourne has 200 synaesthetes on their database - the largest in the world - and they estimate there could be as many as 1 in 2000 people with synaesthesisa.
"Many synaesthetes don't realise they have the condition. They are unaware that the way they perceive the world is different," say Rich.
In most people, a particular physical stimulus presents a single united perceptual experience: light gives us a visual experience, sound an auditory experience, odour an olfactory experience.
Synaesthetes, however, get an extra one or more perceptual experiences. For example, a particular sound might induce vivid experiences of color, taste or odour. Visual symbols like letters or numbers might elicit specific colors producing for the person a kaleidoscope experience.
This extra layer of information may be behind synaesthetes' excellent rote memory.
"They have color as an extra bit of information to help them remember things like names and strings of numbers," says Rich.