Synaesthesia (or synesthesia) is a neurological condition in which the stimulation of a sense (like touch or hearing) leads involuntarily to the triggering of another sense (like sight or taste).
For example, a person with synaesthesia might see the colour blue when they hear the word ‘fish’ or, as in mirror-touch synaesthesia, they would feel a physical sense of touch on their own bodies when they witness touch to other people or objects. This inter-sensory mixing is caused when the brain uses the resources usually used for seeing for other senses.
People with synaesthesia tend to be drawn towards the creative arts and some artists have explored the concept in their works, like the Russian abstract artist Wassily Kandinsky, who had an interest in visualising music in his paintings. In the film Sensorium Tests which explores mirror-touch synaesthesia, the contemporary artist Daria Martin challenges the idea that the act of looking is a passive experience.