SYNAESTHESIA

In the 19th and early 20th centuries, scientists were fascinated by synaesthesia: the way some people perceive sensations joined together, like seeing letters of the alphabet in a range of colours or hearing music as texture. Victorians named it after the Greek for union (syn) of sensations (aesthesia). In the west, the research fell out of fashion in the mid 20th century, but since the 1980s it’s been rediscovered, helping neuroscientists to understand how we separate and combine sensations.
Classic synaesthesia is something people are born with; cognitive synaesthesia happens when our minds join different sensations, based on our experiences. It’s used by perfumers in the creative process; for example, fragrances are often inspired by listening to music. It’s the psychological side of aromatherapy.