Some individuals have intense physical synesthetic responses to any physical touch they see, while others describe their experiences as feeling an 'echo' of the touch that they see. The severity of the condition varies from person to person. Synesthesia is usually a developmental condition however, recent research has shown that mirror touch synesthesia can be acquired after sensory loss following amputation. Synesthesia, in general, is described as a condition in which a concept or sensation causes an individual to experience an additional sensation or concept. For example, if someone with this condition were to observe someone touching their cheek, they would feel the same sensation on their own cheek. 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.