Strange Brain: People can see Sounds
Sound-visual illusions such as the McGurk effect, when the visual component of one sound is paired with the auditory component of another sound, leading people to mysteriously perceive a third sound — for instance, when the syllables “ba-ba” are spoken over the lip movements for “ga-ga,” the perception is of “da-da” are well documented and well-known. Researchers used another type of sound-visual illusion, the sound-induced flash illusion, to demonstrate that some people may actually see sounds if the parts of the brain devoted to vision are small (journal Proceedings of the Royal Society; PNAS; October 24 2012). They based their results on magnetic resonance imaging (MRI) analyses and on the fact that when a single flash is followed by two bleeps, people sometimes also see two illusory consecutive flashes. Results demonstrate that person having a small visual cortex was more likely to experience the illusion and a link between the perception and the individual brain anatomy. Results also show that the visual brain’s representation of what hits the eye is not perfect. Some uncertainty to visual representations, especially when things happen quickly, like the rapid succession of flashes in the illusion exists. Finally, only about a quarter of the individual differences regarding the illusion could be explained by brain anatomy. The rest remains unknown.
Here another illusion discovered by Ladan Shams, Yukiyasu Kamitani, and Shinsuke Shimojo.