Sights and Sounds: Photisms

Have you ever lay in your bed, peacefully clothed in the still darkness of night, when all of a sudden a loud sound startled you and a flash of light or colors appeared momentarily? If so, you may have experienced a synaesthetic phenomenon known as a "photism." Sounds, touch, and taste can elicit transitory visual sensations such colors or light. A few research centers have studied grapheme photisms -- colors or lights induced by the sounds or sights of certain letters, vowels, and numbers. A certain vowel will consistently induce a certain hue of colors, for example in a "color-hearer." Apparently, different languages or speakers may induce different photisms as well. Oftentimes, people with visual loss resulting from optic nerve lesions experience sound-induced photisms. They describe flashes of light, resembling "a flame, a petal of oscillating lines, a kaleidoscope, or an amoeba." One characteristic that is common to all photisms in the visually impaired group is the startle response that provokes them. The ability to experience photisms is poorly understood, but appears to be related to cross-wiring in the thalamus (subcortical portion of the brain involved in processing visual and auditory information). Approximately 1% of the population reports seeing these phenomena, and there has been a genetic basis to its incidence. If a tree falls in the forest and makes a sound, does it also induce a photism?



L. Jacobs et al. Auditory-visual synthesia: sound-induced photisms. Archives of Neurology. 1981; vol 38, Nov 4: 211-216.


Seeing Sounds Or Hearing Colors: Scientists Narrow Search For Genes Associated With Synesthesia. Science Daily. July 26, 2007.


Explanation For Synesthesia? Area Deep Within Brain Plays A Role In Sensory Perception. Science Daily. Sept 24, 2007.