Is Wednesday red? Take part in our experiment to test whether your senses overlap.
Do melodies have a colour? Take part in our experiment to test whether you hear colours.

Imagine if every time you saw someone called Derek you got a strong taste of earwax in your mouth. It happens to James Wannerton, who runs a pub. Derek is one of his regulars. Another regular’s name gives him the taste of wet nappies. For some puzzling reason, James’s sense of sound and taste are intermingled.

Dorothy Latham sees words as colours. Whenever she reads a black and white text, she sees each letter tinged in the shade of her own multi-coloured alphabet – even though she knows the reality of the text is black and white. Spoken words have an even stranger effect. She sees them, spelled out letter by letter, on a colourful ticker tape in front of her head.

Both James and Dorothy have a mysterious condition called synaesthesia, in which their senses have become linked. For years scientists dismissed it, putting it in the same category as séances and spoon-bending. But now, synaesthesia is sparking a revolution in our understanding of the human mind.

Two synaesthetes seldom agree on the colours or tastes they experience. While Covent Garden may taste of crinkly chocolate to James, it’s very unlikely to have the same taste for another synaesthete. And Dorothy’s brother Peter, also a synaesthete, won’t see M or Z in the same colour as she does. But despite these differences, scientists are now beginning to discover more and more overarching synaesthetic patterns.

Dorothy doesn’t only see letters and numbers in colour. Music produces a riot of colour, too. As Dorothy hears notes going from low to high, her colours change from black and purple to mid-browns and then yellows and whites. Overall, lower notes evoke darker colours and higher notes brighter colours – and this pattern is true for most synaesthetes.

But surprisingly, when non-synaesthetes are asked to match colours