May 30, 2025, 2:54 pm | Read time: 6 minutes
As a cat owner, you might swear that a cat recognizes its owner by the sound of their voice, the steps on the stairs, and even their scent. This has now been scientifically examined for the first time in a study from Japan. The study provides clear evidence that cats can distinguish well between familiar and unfamiliar people—with a fascinating “nose habit” that is sure to bring a smile.
Cats have a highly developed sense of smell, which they use extensively in social interactions with other cats. Whether it’s recognizing individuals, assessing health status, or determining reproductive readiness, this sense is more pronounced than their vision and allows them to sniff out prey and determine if it’s still edible. Cats also use it to identify and differentiate between humans, as a study by the Tokyo University of Agriculture now shows. They even seem to have a preferred nostril for sniffing owners or strangers.
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The research team led by Yutaro Miyairi conducted a study published in May 2025 in the scientific journal “PLOS ONE” to investigate whether domestic cats can distinguish humans by smell. The study focused not only on whether cats differentiate when meeting strangers but also on how they use their noses—specifically, the left or right nostril. The researchers also recorded the cats’ personality traits and the quality of the human-animal relationship to identify possible behavioral correlations.
For the study, 30 domestic cats (11 male, 19 female; average age 7 years) were observed in their familiar environment. Each cat received three scent samples:
- one from their owner (familiar),
- one from a stranger of the same gender (unfamiliar), and
- a neutral (empty) sample as a control.
The samples were collected by the respective individuals using cotton swabs from particularly odor-intensive body areas (e.g., armpit, behind the ear, between the toes). The human participants were instructed to avoid exercise and strong-smelling foods to ensure the cats could solely detect the human “pheromone bouquet.”
Each cat completed three test rounds, with the positions of the samples varied. In each test, three samples were presented, slightly offset, to clearly assess the cats’ orientation. The cats’ behavior—especially the duration and number of sniffing actions and which nostril was used—was recorded and analyzed via video. Additionally, the owners completed questionnaires about their cats’ personalities. The “Feline Five” model and the CORS scale for analyzing the human-animal relationship were used for this purpose.
Cats’ Brains Process Sensory Impressions Differently
Compared to dogs, research on social cognition in cats is still relatively new. Previous studies have already shown that cats can recognize humans by voice and gaze and respond to their emotions. However, whether cats can identify humans solely by smell was previously unclear.
The focus on the different nostrils of the animals was not without reason. In many animal species such as dogs, horses, and fish, it is known that they prefer one nostril for processing new smells. This suggests lateralization or specialization of different brain hemispheres. As the work of the Japanese researchers shows, this also exists in cats, which followed a reproducible pattern when sniffing.
Cats Sniff Longer to Identify Unfamiliar Humans
The study also showed that cats sniff about twice as long at the scent sample of an unfamiliar person. They also showed a clear nostril preference here. When first sniffing unfamiliar scents, they more often used the right nostril. This parallels other animal species, where the right nostril is also associated with processing new or potentially alarming stimuli. This tendency was confirmed even with samples placed on the left side, as cats actively turned to use the right nostril.
As the investigation progressed, however, they more frequently switched to the left side. Interestingly, many cats rubbed the corresponding side of their face against the scent source after sniffing. This behavior is part of their scent-marking behavior, which helps them “mix” unfamiliar smells with their own and make sense of them.
Particularly intriguing: Male cats showed a clear connection between the frequency of sniffing and certain personality traits. Male cats with higher neuroticism scores sniffed more intensely at various scent tubes and switched between samples more often. In contrast, males with higher agreeableness scores approached the scent source less frequently and sniffed more calmly. These behaviors suggest that personality significantly influences male cats’ reactions to scent stimuli. These associations were not found in female cats.
Sniffing Behavior when Cats Identify Humans Likely Not Learned Through Human Bonding
The results underscore that olfactory perception and individual personality are closely linked in cats. Particularly, the behavior of male animals is significantly influenced by personality traits, indicating gender-specific differences in cats. The subsequent rubbing with the respective side of the face used could be part of a complex recognition and marking behavior that combines unfamiliar scents with their own.
In contrast to personality, the relationship between the cat and the owner initially seems to have no obvious impact on olfactory exploration behavior. This suggests that sniffing behavior is largely independent of experience or learning processes. However, it was found that the human-cat relationship is closely linked to the time spent together and emotional closeness (measured with the CORS scale).
The study provides the first systematic evidence that cats can recognize familiar and unfamiliar people by their body odor and that they take more time to evaluate new smells than familiar ones. The sense of smell plays a crucial role, and lateralization—the preferred use of one nostril—could offer insights into the emotional states of cats during scent perception in future studies.
Conclusion
The study opens new perspectives on the social perception and communication of cats. It appears they have a strong preference for sniffing strangers with their right nostril and then engaging in marking behavior. The animals’ personality traits also seem to significantly influence their response to scent stimuli, although the study’s sample size was relatively small. Further research can build on these findings to determine whether cats generally distinguish only between “familiar” and “unfamiliar” or can specifically recognize individual humans by scent.
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About the Author
Louisa Stoeffler has been working as a cat sitter since 2016 and knows the subtle nuances in animal behavior from experience. In addition to her practical work, she has been writing in-depth articles for PETBOOK since 2022 on cat care, wildlife, animal protection legislation, and natural history studies. She is particularly passionate about mollusks, for which she has developed a special interest. Her goal: to make complex connections understandable, strengthen animal protection, and raise awareness of the diversity of the animal world.