Too well connected

摘要

Some people have a more complicated sensory life than others. Most taste tuna only when they eat it. A few, though, taste it when they hear a particular word, such as "castanet". Others link the colour red with the letter "S" or make some other inappropriate connection between stimulus and response. Such people are known as synaesthetes, and the phenomenon of synaesthesia has puzzled brain scientists since it was recognised over a century ago.