A new study has found that humans are able to perceive odor changes in fractions of a second, contrary to the belief that odors are perceived as a whole without discernible temporal structure within a single sniff. The study, published in Nature Human Behaviour, used a device that allows for precise odor control to determine that participants were able to discern different sequences of odors with above-chance accuracy, even when the odors were delivered only 60 milliseconds apart. This suggests that our sense of smell has a speed similar to that of color perception.
The research was conducted by Wen Zhou and her team at the Chinese Academy of Sciences in Beijing, who designed a device that is able to detect the beginning of a sniff using changes in nasal pressure and releases two odors, one slightly farther from the nose than the other. Over 200 participants were exposed to sequences of two chemical odors in a single sniff with millisecond precision. The odors ranged from pleasant scents like apples and flowers to less pleasant scents like onions and lemon. Participants reported which order of odors they perceived in the sniff sequence.
The results of the study suggest that humans are able to perceive much more detail within a single sniff than previously thought. This challenges the idea that each sniff feels like taking a long-exposure shot of the chemical environment, as intuition would suggest. The findings demonstrate that our sense of smell has a rapid speed similar to that of color perception, allowing us to discern odor changes in fractions of a second.
The next step in the research is to investigate how the brain processes information from sniff to sniff, especially given that our noses can detect over a trillion odors. Wen Zhou plans to explore how the brain processes temporal information within and between sniffs, as well as how different odors are distinguished within the olfactory system. The study raises questions about how our sense of smell operates and the speed at which we are able to perceive and distinguish different odors.
