The ‘mind’s nose’ might actually be a thing

If I asked you to conjure the image of a slice of lemon in your mind, could you do it? What if I then asked you to imagine its scent?

It's widely accepted that most people are capable of picturing an object in their mind — as well as imagining sounds and movements of objects, write the authors of a new study in the Journal of Experimental Psychology: Human Perception and Performance. However: "There is a seemingly widespread belief among olfactory researchers that the human ability to imagine odours may be severely limited or even non-existent." Their new research contradicts this belief — in fact, the ability to imagine a wide range of specific scents seems to be common.

In the first stage of their two-part study, Stephen Pierzchajlo at Stockholm University and colleagues got 37 Swedish-speaking adults to sniff a total of 16 odours in the lab. The participants scored each odour on a number of factors, including pleasantness. (These odours, which were taken from the Sniffin' test of odour based memory, ranged from smells such as petrol and garlic all the way to apples and fish.)

Then, the participants were given pairs of these odours to sniff, and asked to judge how similar the two scents were on a scale from 0 to 100. Every single possible pairing was presented twice. In the second half of the experiment, the order was reversed; so, for example, if in the first half, banana was paired with lemon, and the participant sniffed banana before lemon, in the second set of trials, they instead sniffed lemon first.

When the team analysed these results, they found that the similarity ratings for each pair in the first and second halves of the experiment were very consistent. This gave them confidence that the ratings were reliable — rather than being wild and random responses.

For the second major stage of the study, which was conducted online, the researchers recruited about 2,000 Swedish adults, who fell into two age ranges — 20 to 45 and 60 to 85. In this experiment, participants were shown a series of a single 'target' odour names from the set of 16, plus four others, one of which was also from the set of 16. Each time, they rated how similar each of the other four odours were to the target on a scale from one to five.

The researchers then compared the average similarity ratings for the scent pairs from the first stage of the study with average similarity ratings for the same pairs from the second stage. They found a strong positive correlation — ratings from people who'd had to imagine how similar a given pair of scents would be were very similar to those from different people who had actually sniffed and compared them.

"Our results suggest that people are capable of mentally evoking and comparing odour pairs when presented with their known labels," the team writes.

They also found that although pairs of scents that had been deemed to be more equally pleasant (or unpleasant) in the first stage also got higher similarity scores, pleasantness didn't explain the similarities between the ratings from the lab-based and the online participants. (Rather, it only supported the well-established finding that pleasantness is the most important perceptual feature of an odour, they write.)

Notably, though smelling ability is known to deteriorate with age, and some studies have found that women have more sensitive noses than men, they didn't find that age or gender affected the similarity ratings.

These findings suggest that just as the vast majority of people can represent visual images in a perceptual 'space' in their minds, we do something very similar with odours. And this may have everyday implications. Some recent research has found, for example, that people who find it easy to imagine odours have stronger food cravings and put on more weight. More work is now needed to explore odour imagery abilities in other groups — not just Swedish adults, or people who seem to be especially good at it — and the possible real world effects.

Read the paper in full:
Pierzchajlo, S., Hörberg, T., Challma, S., & Olofsson, J. K. (2025). Evidence from odor similarity judgments suggests a widespread ability to imagine odors. Journal of Experimental Psychology: Human Perception and Performance, 51(5), 629–642. https://doi.org/10.1037/xhp0001292 

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