SYNAESTHESIA, the phenomenon in which the senses are mixed up and people link, say, tastes with musical notes, comes in at least two different flavours.
Edward Hubbard and his colleagues at the University of California, San Diego, put six people who associate letters and numbers with various colours through a series of experiments, comparing them with six controls. In one of the experiments, known as the “crowding task”, volunteers have to pick out a particular letter or number from a jumble of others.
The more letters in the mix, the harder it is to pick out the target. If different…
