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 diapers. For some puzzling reason, James's sense of sound and taste are intermingled. Julian Asher can hear colors. Others can taste shapes, smell sounds, feel smells. It's called synesthesia, a truly bizarre condition in which our senses become intermingled, and has baffled scientists for decades.