Synesthesia is a perception and sensation anomaly in which the stimulation of one sense results in other senses being activated. As a musician, I think of of practicing an imaginary piano (or ‘air guitar’, or reading an orchestral score) and ‘hearing’ the pitches with the ‘inner ear’. Or ‘hearing’ words and vocal inflections when reading text.
Synesthesia is additive; it adds to the initial (primary) sensory perception, rather than replacing one perceptual mode for another.
Often synesthesia is considered a neurological condition, but it is not listed in the DSM-IV or the ICD since it usually does not interfere with normal daily functioning. The neurological correlates of synesthesia have yet to be be established.
Their are two overall forms of synesthesia: ‘projective’ synesthesia and ‘associative’ synesthesia. Projectors will see actual colors, forms, or shapes when stimulated; associators will feel a very strong and involuntary connection between the stimulus and the sense that it triggers.
This research explores the premise that associative synesthesia can be developed and refined in adults with training rather than being only something that an individual is born with. This early research has remarkable implications for perceptual/conceptual exploration of (pitch-color) synesthetic integration for musicians and listeners. The possibilities for ‘pitch-color’ association training and multi-sensory musical experience are profound.
Broadly, I think of synesthesia as perceptual multi-sensory integration. And in addition to the other multi-sensory integrations gained through musical training (auditory-visual, auditory-tactile, auditory-proprioceptive, etc), a developed synesthetic association of auditory pitch and visual color will lead to expansive new worlds of musical awareness, understanding and creativity.
This article presents early research (2014) on the acquisition of synesthetic perception. Through training with letter-color associations, adults were able to acquire synesthetic perceptual integration. The perceptual integration was short-lived (< 3 months), but the training sessions were limited to only 9 weeks.