Synaesthesia (from Gk. syn: ‘union’ and aisthesis: ‘sensation’)
- Jörg Jewanski
(from Gk. syn: ‘union’ and aisthesis: ‘sensation’)
The general name for a related set of cognitive states. Synaesthesia may be divided into two general, overlapping types. The first is ‘synaesthesia proper’, in which stimuli to one sensory input will also trigger sensations in one or more other sensory modes. The second form of synaesthesia, called ‘cognitive’ or ‘category synaesthesia’, involves synaesthetic additions to culture-bound cognitive categorizational systems. With this kind, sets of things which our individual cultures teach us to put together and categorize in a specific way – like letters, numbers, or people’s names – also get sensory addition, such as a smell, colour, or flavour. The most common forms of cognitive synaesthesia involve such things as coloured written letter characters (graphemes), numbers, time units, and musical notes.
Synaesthesia has neurological components and is partly heritable. The percentage of the general human population which has synaesthesia varies with the roughly 60 types involved; estimates run from about 4% for basic types of cognitive synaesthesia (coloured letters or musical pitches) to about 0.03% for more common forms of synaesthesia proper (coloured musical sounds or coloured taste sensations) to less than 0.01% for people with rare or multiple forms of synaesthesia proper....