Do we all have some synaesthetic ability?
By Alison Motluk So, you think you’re not synaesthetic. You might have to think again. New research shows that many people have traces of the condition without realising it. Synaesthesia is a condition in which people make unusual associations across the senses. Some people perceive letters, numbers, words and smells to have innate colours, while others can taste music or imagine time to have a fixed special form. Ferrinne Spector and Daphne Maurer at McMaster University in Hamilton, Canada, were interested in exploring the coloured and textured smell that some synaesthetes experience. They asked 78 people who considered themselves non-synaesthetes to smell 22 separate odours in glass jars and assign each a colour and a texture. The experiment included odours that were both pleasant and unpleasant and familiar and unfamiliar, and that fitted broadly into four categories: food, floral, chemical and environmental. Volunteers were asked to look beyond the obvious, say, orange for an orange scent. When the researchers analysed the results, along with some obvious associations – lemon with yellow and peppermint with smooth, hard and sticky – they found some odd ones. Significantly more people than chance, for instance, associated the smell of mushrooms with the colours blue or yellow. Lavender elicited the colour green and the texture of sticky liquid, while ginger was perceived as black and sharp. “The influence of learning is there,” Spector told a meeting of the American Synesthesia Association in Hamilton on 27 September, “but it cannot explain all associations.” In a separate experiment, Ursina Teuscher, at the University of California at San Diego, and her colleagues asked 191 people whether they saw the months in a spatial arrangement. Eighty-nine said they did not. But when the researchers asked volunteers to click on a computer screen to plot where they perceived months to be, non-synaesthetes produced similar arrangements to synaesthetes – including straight lines, curvy lines, ovals, circles and rectangles. Some were so consistent with synaesthete representations that the researchers decided to divide them not by whether they declared themselves a synaesthete or not, but rather by their accuracy in replicating their own mental representation. “More consistency predicts a less conventional calendar,” Teuscher told the meeting. Teuscher called for researchers of synaesthesia to be more rigorous. She pointed out that they are all very careful to make sure professed synaesthetes meet the criteria before considering them bona fide synaesthetes, but less so the other way round. “If people say they don’t have synaesthesia, we feel we don’t have to validate that,” she says, “and maybe that’s a big mistake.” The Human Brain – With one hundred billion nerve cells, the complexity is mind-boggling. Learn more in our cutting edge special report. More on these topics: