WHAT DEFINES SYNESTHESIA?
Synesthesia can be acquired via epilepsy or the ingestion of hallucinogens such as mescaline or LSD, but idiopathic (or developmental) synesthesia arises naturally without an external agent or brain abnormality. There is nothing in need of medical treatment. The subjective, ineffable, and idiosyncratic nature of this kind of synesthesia does make it an easy target for dismissal. Even the term “synesthesia” has been used imprecisely over time, referring to everything from metaphor (loud tie, sharp cheese, sweet voice) to deliberate contrivances such as son et lumière theatrical performances and “smellavision.” A clear definition avoids a muddle. Idiopathic synesthesia is defined by five clinical findings: It is (1) involuntary and automatic, (2) spatially extended, (3) consistent and generic, (4) memorable, and (5) affect-laden. These refer to specific characteristics of the synesthetic person’s experience.
