The case study, reported in the October issue of Cognitive Neuropsychology, shows how some people can experience colours in response to people they know or words that evoke emotions - a condition known as emotion-colour synaesthesia.
Dr Jamie Ward, author of the study, says: "A popular notion is that some people have a magical ability to detect the hidden emotions of others by seeing a colourful 'aura' or energy field that they give off. Our study suggests a different interpretation. These colours do not reflect hidden energies being given off by other people, rather they are created entirely in the brain of the beholder."
In the study, Dr Ward of UCL's Psychology Department documented a woman known as GW who could see colours like purple and blue in response to people she knew or their names when read to her. Words triggered a colour which spread across her whole field of vision, whilst people themselves appeared to have coloured 'auras' projected around them. For example, "James" triggered pink, "Thomas" black and "Hannah" blue.
A similar test using 100 words rated on a scale of 1 to 7 for their emotional impact showed that highly emotive words such as fear or hate also triggered colours. Words associated with positive emotions tended to elicit pink, orange, yellow, and green, whereas words associated with negative emotions triggered brown, grey, and black.
Whilst it is quite common to describe people or emotions metaphorically in terms of colours, GW actually reported vividly seeing them. Indeed, when "James" (a pink word) was written in the wrong colour (e.g. blue), her reaction times were slowed.
Synaesthesia is a condition found in 1 in 2000 people in which stimulation of one sense produces a response in one or more of the other senses. For example, people with synaesthesia may experience shapes with tastes or smells with sounds. It is thought to originate in the brain and some scientists believe it might be caused by a cross-wiring in the brain, for example between centres involved in emotional processing and smell perception. Synaesthesia is known to run in families.
GW, 19-year old with an IQ of 112, became aware of her condition around the age of seven but refrained from telling her family or friends. In GW's case, people acquired a synaesthetic colour as she got to know them and the colour was then triggered whenever she was presented with the person's name or face.
In contrast, a case discovered in the 1930s documents a seven year old boy who also associated colours with people, but saw strangers in bright orange with a black outline which faded to a mild blue and finally pink when he got to know them.
Dr Jamie Ward continues: "The ability of some people to see the coloured auras of others has held an important place in folklore and mysticism throughout the ages. Although many people claiming to have such powers could be charlatans, it is also conceivable that others are born with a gift of synaesthesia.
"GW does not believe she has mystical powers and has no interest in the occult, but it is not hard to imagine how, in a different age or culture, such an interpretation could arise.
"Rather than assuming that people give off auras or energy fields that can only be detected by rigged cameras or trained seers, we need only assume that the phenomenon of synaesthesia is taking place."