Imagine seeing blue whenever you read the letter ‘A’ or tasting cinnamon whenever someone says your name. These are examples of the phenomenon known as synesthesia. With this neurological condition, one involuntarily perceives a mixed range of sensations in response to a stimulus. There are several different permutations of synesthesia, from the more common text-color linked types to the rarer lexical-gustatory variants.
Not much is known about the nature of synesthesia – it is mainly self-reported and reliable testing methods are still being developed. Professor Larry P. Marks, Emeritus Director of the John. B Pierce Laboratory, has experience with such methods of testing for synesthesia. In one method, people believed to be synesthetes are periodically asked to describe their experiences; true synesthetes will generally make the same mixed sensory associations throughout their entire lives. Scientists also use brain scanning to confirm synesthesia. In some cases, people who see color when they hear sounds exhibit an abnormal stimulation of their visual cortexes upon hearing music.
Synesthesia research may lead to a better understanding of general cognitive processes. Theories of physiological causes of synesthesia, such as hyperconnectivity of neurons in the brain, have prompted further examination of human cognitive development. Marks says that a new study will be conducted to link the biological mechanisms of synesthesia to those of migraine headaches. Hoping to apply the knowledge of synesthetic processes to general cognitive functions, Marks continues to explore this phenomenon of synesthetic perception.