If someone were to invent "smellovision", it seems we might all end up watching the same show slightly differently – researchers have discovered that our sense of smell can affect how we perceive color.
Humans are constantly bombarded with sensory information: the whirr of the computer fan as you work; the bright white of that pesky Excel spreadsheet; the smell of dinner in the crockpot downstairs. To make sense of all these inputs, the brain often combines them. This means that one sense can unconsciously affect another, known as crossmodal association.
It turns out that one of these associations occurs between our sense of smell and our sight, with a new study finding that smell can affect color perception. Using experiments involving sensory deprivation, the research team found that the presence of different odors can influence how we might perceive a particular color.
"In a previous study, we had shown that the odor of caramel commonly constitutes a crossmodal association with dark brown and yellow, just like coffee with dark brown and red, cherry with pink, red, and purple, peppermint with green and blue, and lemon with yellow, green, and pink," explained lead author Ryan Ward, in a statement.
The new study, however, wanted to establish if scent affected the perception of the same color.
The experiment, in which 24 adults participated, took part in a specially designed room. Although not exactly the level of sensory deprivation seen in Stranger Things, several senses were carefully controlled: windows were blacked out, lights were turned off, and an air purifier removed any odors from the room. Participants also had to refrain from wearing deodorant or perfume, so hopefully they showered that day.
They also sat in front of a screen filled with a random color, whilst an ultrasonic diffuser pumped one of six odors into the room – caramel, cherry, coffee, lemon, peppermint, or water as a control – for five minutes. Using two sliders, participants were then asked to manually adjust the color on the screen to what they perceived to be true neutral gray.
The study found that people had a weak but significant tendency to shift the color too far away from neutral gray, in different but predictable ways depending on the scent – except for peppermint. The smell of coffee made participants perceive gray as a more red-brown color, whilst caramel led to more of a yellow-brown. To be expected given their respective dullness, odorless water corresponded to true neutral gray.
"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.
"This 'overcompensation' suggests 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."
To what extent this association occurs is yet to be determined, but researchers hope this will be the subject of future research. "We need to know the degree to which odors influence color perception,” stated Ward. “For example, is the effect shown here still present for less commonly encountered odors, or even for odors encountered for the first time?"
Guess we’ll have to wait and see… or smell, to find out. Talking of senses, why don’t you find out about the new sixth taste in the meantime?
The study is published in Frontiers in Psychology.