The sense of smell changes the colors we see

The five senses provide us with information about our environment 24 hours a day, 7 days a week. One way our brain makes sense of this wealth of information is by combining information from two or more senses, such as smell and texture, tone, color, and musical dimension.

This sensory integration also causes us to associate higher temperatures with warmer colors, lower sounds with lower pitches, and colors with the flavors of certain foods, for example, oranges of the same color.

A study published in the journal Frontiers in Psychology experimentally demonstrated that these unconscious "multimodal" connections with our sense of smell can influence our perception of color.
Lead author Dr Ryan Ward, senior lecturer at Liverpool John Moores University in Liverpool, UK, said: "Here we show that the presence of different odors affects how people perceive color.".

The study on smell was carried out in a special room

Ward and his colleagues evaluated the existence and strength of the association between odor and color in 24 adult women and men between 20 and 57 years old. Participants sat in front of the screen in a room free of unwanted sensory stimuli throughout the experiment. They did not use deodorant or perfume, and none reported being color blind or having olfactory problems.

An air purifier removed all ambient odors from the room in a matter of minutes. One of six scents (randomly selected from caramel, cherry, coffee, lemon and mint plus unscented water as a control) was then introduced into the room using an ultrasonic diffuser for five minutes.

"In a previous study, we showed that candy odors tend to intersect with dark brown and yellow colors, as do coffee odors with dark brown and red colors, and cherry odors with pink and red, and purple colors, mint with green and blue and lemon in yellow, green and pink”Ward explains.

Participants were shown a screen projecting a square filled with random colors (from an infinite range) and were asked to manually adjust two sliders, one from yellow to blue and one from green to red, to bring their color to neutral gray.
After making the final selection, the procedure was repeated until all odors appeared about five times.

Overcompensation for unconscious associations

The results showed that participants had a weak but significant tendency to place one or both sliders too far from neutral gray. For example, when exposed to the smell of coffee, they mistakenly perceive "gray" as more reddish brown than a true neutral gray. Similarly, when they smell sweets, they confuse the color blue with gray. Therefore, the presence of odors could influence participants' color perception.

The only exception was when the mint odor was present: in this case, participants' tone choices differed from the typical cross-modal relationship shown for other odors.
As expected, the participants' choice also corresponded to the pure gray color with the neutral aroma of water.

"These results indicate that gray perception generally shows the expected cross-modal correspondence for four of the five aromas, namely lemon, caramel, cherry and eggplant."Ward said."This overcompensation suggests that the role of intermodal connections in sensory processing is strong enough to influence how we perceive information received through different senses, in this case it is smell and color.".

The question remains about the relationship between smell and color

Scientists emphasize the need to investigate the extent of cross-modal associations between odor and colour.
"We need to know to what extent smell affects color perception. For example, does the effect shown here apply to less frequent odors or even odors encountered for the first time?"Ward said.

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