Sixes Are Blue And Ten Is Always Yellow

When I was a child my aunt Eleanor would amuse us by doing complex arithmetic like long division in her head without the aid of pencil or paper or calculator. She assigned colours to numbers. "Sixes are blue and ten is always yellow..." she would say and then come up with the correct answer every time. This ability is known as synesthesia.

From Science Daily: "For years, synesthesia was dismissed as the product of someone's overactive imagination. But in the past decade, researchers have documented hundreds of cases of otherwise normal people ... Who have these extraordinary blended senses."

Scientists are now trying to unlock the secrets of synesthesia by using magnetic resonance imaging scans (MRIs) of people's brains.