ANNE MCILROY

From Saturday's Globe and Mail

When Candace Osborne Bell gets a back massage, she sees rich, golden yellows, oranges and greens in her mind's eye. A recent meal of pasta and sauce tasted dark purple. When she walked by a sewer grate, she smelled a swirl of pink and brown.

“It was the colour of melted Neapolitan ice cream,” says the 22-year-old fine-arts student at McMaster University in Hamilton.

The senses mingle in people like Ms. Bell, who have what scientists call synesthesia. In her case, touches, tastes and smells can also be experienced as colours. Her alphabet is rainbow hued, with every letter a distinct shade: A is always baby blue, while C is cotton-candy pink, and some letters have more personality than others.

It is estimated that one in 2,000 people have synesthesia. Some see colour sensations in front of their eyes when they listen to music. Brain imaging studies have shown these are genuine perceptual experiences — when they hear a sound, the regions of the brain that process colour are activated.