What is Synesthesia?
It is a perceptual phenomenon where activation of one sensory or cognitive channel leads to involuntary experiences in another sensory or cognitive pathway. Synesthetes are people who have had such experiences for a lifetime. Synesthetic awareness varies from person to person. Grapheme–color synesthesia, or color–graphemic synesthesia, causes letters or numbers to appear coloured. Numbers, months of the year, or days of the week might evoke particular locations in space (for example, 1980 may be “far distant” than 1990), or appear as a three-dimensional map (clockwise or counterclockwise). Synesthetic associations can occur across many senses or cognitive pathways. Synesthesia is a rare condition. Synesthesia may emerge in childhood when children are first exposed to abstract concepts. This concept explains why the most prevalent synesthesias are grapheme–color, spatial sequence, and number form. These are frequently the first abstract notions taught in schools. Synesthesia is a difficult concept to define. Synesthesia (from the Greek words v and, meaning “union of the senses”) has been used to a wide range of experiences, and the concept is often misleading. Ideasthesia is a more accurate but rare term. In 1690, the Oxford professor and philosopher John Locke reported about a blind man who believed he sensed the colour crimson after hearing a trumpet. However, whether Locke portrayed a real incident of synesthesia or used a metaphor is debated. The first medical report was by Georg Tobias Ludwig Sachs in 1812. The word comes from the Greek syn and aisthsis, which means “together”.