Mirror-touch synesthesia is a rare condition which causes individuals to experience a similar sensation in the same part or opposite part of the body (such as touch) that another person feels. For example, if someone with this condition were to observe someone touching their cheek, they would feel the same sensation on their own cheek. Synesthesia, in general, is described as a condition in which a stimulus causes an individual to experience an additional sensation.[1] Synesthesia is usually a developmental condition; however, recent research has shown that mirror touch synesthesia can be acquired after sensory loss following amputation.[2]
The severity of the condition varies from person to person. Some individuals have intense physical synesthetic responses to any physical touch they see,[3] while others describe their experiences as feeling an "echo" of the touch that they see.[4] This appears to be comparable to the projective versus associative distinctions found in other forms of synesthesia. In addition, some mirror-touch synesthetes feel the phenomenon only in response to other humans being touched, while others also perceive it when animals or even inanimate objects are being touched.[5]