Can odors disrupt our color perception?

The brain constantly combines multisensory information from the environment. For example, smells are often perceived using visual cues; These perceptions interact and create their own subjective experience. This integration process can have a profound impact on the resulting experience and can alter subjective reality.

Cross-modal correspondences are consistent associations between stimulus features in different sensory inputs. These correspondences are believed to be bidirectional in nature and have been shown to influence perception in many different ways. Vision is dominant in multisensory perception and can affect how information is perceived by other senses, including smell.

The combination of information from two or more senses, for example between smells and the softness of textures, tone, color and musical dimensions, also causes higher temperatures to be associated with warmer colours, lower tones of sound with less elevated positions and colors with the taste of certain foods (such as the taste oranges with their shade).

Now a study published in Frontiers in Psychology has experimentally demonstrated that these unconscious cross-associations with smell can affect color perception. “Here we show that the presence of different odors affects how people perceive colors,” explained lead author, Ryan WardSenior Lecturer at Liverpool John Moores University in Liverpool, United Kingdom.

Ward and his colleagues tested the existence and strength of odor-color associations in 24 adult women and men aged 20 to 57. Participants sat in front of a screen in a room without unwanted sensory stimuli for the duration of the experiments. They did not use deodorants or perfumes, and no one reported being color blind or having problems with smell.

All ambient aromas in the isolation room were removed using an air purifier for four minutes. Then, one of six odors (randomly chosen from caramel, cherry, coffee, lemon, and mint, plus odorless water as a control) was delivered to the room using an ultrasonic diffuser for five minutes. “In a previous study, we showed that caramel odors commonly form intermodal associations with dark brown and yellow, as well as coffee with dark brown and red, cherry with pink, red and purple, mint with green and blue, and lemon. with yellow, green and pink,” Ward explained.

Participants were presented with a screen showing a square filled with a random color (from an infinite range) and asked to manually adjust two sliders, one from yellow to blue and one from green to red, to change their neutral gray tone. Once the final choice was recorded, the procedure was repeated until all odors were presented five times.

The results showed it participants had a weak but significant tendency to adjust one or both sliders too far from neutral gray. For example, when presented with the smell of coffee, they mistook the color gray for a reddish brown rather than a true neutral. Likewise, when faced with the smell of candy, they mistook the blue-enriched color as gray. The presence of odor predictably distorts color perception participants.

The only exception was the presentation of the mint scent: here, participants’ choice of shade differed from the typical association demonstrated for other scents. As expected, participants’ choices also matched the true gray when presented with the neutral odor of water.

“These results show that gray perception tended to correspond as expected for four of the five aromas, namely lemon, caramel, cherry and coffee,” Ward said. This overcompensation suggests that the role of cross-modal associations in sensory information processing is strong enough to influence how we perceive information from different senses, here between smells and colors. We need to know to what extent the former affects the perception of the latter. For example, is the effect shown here still present for odors that we encounter less often, or even for those that we encounter for the first time? “We are analyzing it.