New research has challenged long-held views on human olfaction, revealing that our ability to detect changes in odours is far quicker than once thought. Dr Wen Zhou, a researcher at the Chinese Academy of Sciences, led a team that found humans can distinguish between the order of smells with much greater speed and accuracy than previously assumed. Contrary to the belief that our sense of smell operates slowly, participants in the study demonstrated a remarkable sensitivity to the order of odours arriving at their noses.

Study Methodology

The study, published in Nature Human Behaviour, involved a unique setup where scents were delivered to participants’ noses in rapid sequences. The team devised an apparatus that could deliver two distinct scents at different times during a single sniff. The scents reached participants’ noses within intervals as short as 18 milliseconds. Remarkably, many participants were able to correctly identify whether the order of odours was the same or reversed, even when the difference between the scents’ arrival times was just 40-80 milliseconds.

Key Findings

Dr Zhou explained that while humans could detect when the order of scents changed, it was more challenging for them to pinpoint which smell came first. This sensitivity to the sequence of odours suggests that human perception of smell is shaped by the timing of scents entering the nose. Interestingly, participants were more successful at this task when smelling lemon and onion-like odours, particularly when the time difference between scents was around 167 milliseconds.

Conclusion

The findings challenge the idea that the human sense of smell is less refined than our other senses, such as sight. According to Zhou, the ability to detect small changes in odours is not dependent on recognising the order of smells but rather on a faster, more complex mechanism. This research opens up new possibilities for understanding how the human brain processes sensory information.