Better odor recognition in odour-color synesthesia

“For centuries olfaction has been considered unimportant for humans, and people in the West are poor at naming odors,” Dr Laura Speed, researcher at the Radboud University’s Centre for Language Studies, remarks. “Yet there are individuals who experience vivid color associations when they smell odors.”

Rare: odor-color synesthesia

Synesthesia is an extraordinary phenomenon where a sensation in one of the senses, such as hearing, triggers a sensation in another, such as taste. Letter-color synesthesia is the most common form, where people see letters as having colors, thought to be experienced by around 60% of people with synesthesia. In comparison, odor-color synesthesia is more unique, with only 6% of people with synesthesia having visual experiences when they smell odors.

Laura Speed – a psychologist interested in the relationship between language and perception - and Professor Asifa Majid – a linguist with a special interest in the diversity of languages, cultures and minds, are currently engaged in studying our ability to name smells. They wondered if individuals with odor-color synesthesia might differ to people without synesthesia in the way they think and talk about smells. “Could it be the case that having extra associations between color and odor somehow helps language related to odor?”

Difficult: discriminating smells, naming odors

Speed and Majid asked synaesthetes and non-synaesthetes to name everyday odors on two separate days, and took established tests of odor and color perception. The results provide evidence of better perception for both odors and colors. This is the first time improved perception in the sense that induces synesthesia (smell), and the sense in which the synesthesia is experienced (color) has been documented.

“Synesthetes are better at discriminating colors and smells, and in naming odors”, Speed explains. “We demonstrate humans have greater potential abilities in odor language and thought than is usually observed for typical Western subjects. This is important evidence to understand the human sense of smell, our most neglected sense.”