Odor Influences How Humans Perceive Colors; Unconscious ‘Crossmodal Association’ Affects Our Sense of Smell, Perception [Study]

Do you know that your sense of smell affects how you perceive color? While this might sound odd, a new study suggests that it's indeed the case.

Sense of Smell And Color Perception

Our brain makes sense of this flood of information by combining data from two or more senses, such as scents and the smoothness of textures, pitch, color, and musical dimensions. As a result of this sensory integration, we also link certain colors to the flavors of specific meals, such as the flavor of oranges with the same name, greater temperatures with warmer colors, lower sound pitches with less elevated positions, and so on.

An experimental research study has demonstrated how unconscious "crossmodal" linkages with our sense of smell might influence how we perceive colors. Dr. Ryan Ward, the lead author and a senior lecturer at Liverpool John Moores University in Liverpool, U.K., said the study showed that odors influence how the participants perceived colors.

The study involved 24 adult women and men between 20 and 57 years old. Ward and colleagues subjected them to a test to determine the presence and strength of odor-color correlations. For the trials, the participants were seated in front of a screen in a space free of distracting sensory stimuli. None of them claimed to be color-blind or to have a compromised sense of smell, and neither did they wear deodorants or fragrances.

An air purifier was used in the isolation chamber for four minutes to eliminate all scents in the air. Then, for five minutes, an ultrasonic diffuser released one of six scents chosen randomly from caramel, cherry, coffee, lemon, peppermint, and odorless water as a control to the space.

According to Ward, prior research has demonstrated that the smell of caramel frequently forms a crossmodal connection with dark brown and yellow, just like coffee does with dark brown and red, cherries do with pink, red, and purple, and peppermint does with green and blue. Lemon does with yellow, green, and pink.

Participants were given a screen with a square filled with a random color and asked to manually adjust two sliders to turn the color of the square to a neutral grey by moving the sliders from yellow to blue and green to red. The process was then repeated until all scents had been offered five times after the final choice had been noted.

The findings revealed that individuals exhibited a little but statistically significant propensity to move one or both sliders too far from neutral grey. For instance, they misjudged the color "grey" to be more red-brown than a true neutral grey when exposed to the smell of coffee. Similarly, when exposed to the smell of caramel, they mistook a blue-rich color for grey. Thus, the subjects' sense of color was predictably affected by the fragrance.

The only exception was when the peppermint odor was presented because the participants chose a color different from the typical crossmodal association demonstrated in other odors. The researchers concluded, per Ward, that "the role of crossmodal associations in processing sensory input is strong enough to influence how we perceive information from different senses, here between odors and colors."

What Is Crossmodal Association?

Crossmodal association is the coordination of sensory stimuli involving several brain regions that is typically required in tasks involving pairing visual and auditory stimuli, tactile and visual stimuli, or a similar combination of mental functions. Crossmodal association analysis may be used to detect injuries to the occipital, parietal, or temporal lobes.

Additionally, one can consider it as a sensation in which the stimulation of one sense consistently produces a different sensory outcome typically brought about by the stimulation of a separate sense.

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