We tend to use cross-sensory metaphors in our everyday language quite frequently. For example, she’s a prickly person, or he’s wearing a loud shirt. But what we may not be aware of is that some people, some estimate up to 5% of the population may suffer from neurological (clinical) synesthesia.
Synesthesia is a neurological condition in which stimulation of one sensory or cognitive pathway leads to automatic, involuntary experiences in a second sensory or cognitive pathway.
In one of the most common forms of synesthesia, individuals will perceive letters of the alphabet and numbers with a shaded or tinged color. While different individuals usually do not report the same colors for all letters and numbers, studies with large numbers of synesthetes find some commonalities across letters such as the letter” A” is likely to be colored red.
Another example of synesthesia is where individuals report that some sounds trigger colour, shape and motion. For example, a barking dog may trigger color and simple shapes that arise, move around, and then fade.