New Research Reveals That Human Sense of Smell is Remarkably Sensitive

October 14, 2024

Recent research has revealed that the human sense of smell is far more advanced than previously thought. Contrary to Charles Darwin’s suggestion that our olfactory capabilities are of “extremely slight service,” new findings indicate that humans can detect changes in odors with remarkable speed and sensitivity. Dr. Wen Zhou, co-author of the study from the Chinese Academy of Sciences, explained that while each sniff may feel like capturing a long-exposure image of our chemical surroundings, our ability to discern various scents occurs much more rapidly.

The research, published in the journal Nature Human Behaviour, tackled the longstanding challenge of presenting different odors in a precise sequence during a single sniff. Zhou and her colleagues developed a specialized apparatus featuring two bottles of distinct scents connected to a nosepiece via tubes of varying lengths. This design allowed the scents to reach the nose at different times, with a precision of just 18 milliseconds.

In a series of experiments involving 229 participants, the team tested the ability to distinguish between an apple-like scent and a floral scent presented in a specific order. Participants were asked to sniff the apparatus twice and identify whether the order of the odors had been reversed. The results showed a success rate of 63%, with participants correctly identifying the order of the scents in 597 out of 952 trials. Similar tests using lemon-like and onion-like scents yielded comparable outcomes.

Moreover, the study found that participants could discriminate between odors arriving at intervals as short as 40-80 milliseconds, which is ten times shorter than the previously assumed threshold for olfactory recognition. Despite this ability to identify changes in smell, participants struggled to recall which scent came first, achieving better-than-chance results only for the lemon and onion-like odors when the scents arrived with an average time difference of 167 milliseconds.

Dr. Zhou concluded that the process of odor discrimination operates on a faster timescale than previously understood, suggesting that the perception of smells is influenced more by the timing of their arrival than by accurately recognizing the order of the individual scents.

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