HOW OUR SENSE OF SMELL CHANGES THE COLORS WE SEE

Scientists from Liverpool John Moores University in the UK have drawn a connection between how people smell and see colors.

The body of work, published in the journal Frontiers in Psychology, explains how the human body handles our five senses.

One way is by sensory integration, combining information from two or more senses, such as between smells and the smoothness of textures, pitch, color, and musical dimensions — for example, associating the taste of oranges with the color orange.

Lead author Dr. Ryan Ward studied the “strength of odor-color associations” in 24 adults between 20 and 57 years old. They sat in front of a screen inside an air-purified room “devoid of unwanted sensory stimuli” — including the participants’ own perfume or deodorants.

Ward noted a previous study found whiffs of caramel “commonly constitute a crossmodal association (people who spontaneously match information coming from different senses) with dark brown and yellow.”

Coffee has done the same with red and dark brown; cherry scents with pink, red, and purple; peppermint has been connected to green and blue; and lemon with yellow, green, and pink.

For the new study, caramel, cherry, coffee, lemon, and peppermint, plus odorless water — a control element — were “broadcast into the room with an ultrasonic diffuser for five minutes,” researchers said.

Participants were shown a square filled with a random color “from an infinite range” and given two sliders to change the shade into a neutral grey five times over per scent.

They were found to have a “weak but significant tendency” to adjust one or both of the sliders too far from grey.

For example, with coffee, “grey” was incorrectly perceived to be more of a red-brown color.

For caramel, the color was incorrectly enriched in yellow.

The researchers determined smell distorts color perception in a predictable way. Peppermint was an exception.

“These results show that the perception of grey tended towards their anticipated crossmodal correspondences for four out of five scents, namely lemon, caramel, cherry, and coffee,” said Ward.