Humans can smell much faster than we blink, study reveals

If you compare a human’s nose to a dog’s nose, the former usually comes up wanting. Canine noses are so sensitive, they can smell a human’s stress and use the various odors around them to paint a picture of reality akin to what human eyes do with different colors. By contrast the human nose — though able to distinguish between 1 trillion different scents — seems like a weak imitator.

Yet a recent study in the journal Nature Human Behavior revealed that humanity’s collective sense of smell may not deserve its poor reputation. Scientists from the University of Chinese Academy of Sciences and the Ohio State University studied 229 participants over 649 sessions as they sorted through different scents ranging from apple-like and lemon-like to onion-like.

They learned that human noses are much faster than previously believed, distinguishing between different odors in an interval as short as 60 milliseconds on average. To do this, the scientists built a machine that attaches to the nose and can measure the delivery of a scent with the precision of just 18 milliseconds.

Saying human smell detection is as fast as a blink of an eye is a literal understatement. It is, in fact, half the time it takes for humans to blink, a lightning-fast 120 milliseconds.

"Our study shows that humans are inherently sensitive to fast chemical dynamics within a single sniff,” the study's lead author, Dr. Wen Zhou from the Chinese Academy of Sciences' Institute of Psychology, told Salon. “Not surprisingly, this temporal sensitivity varies from one individual to another. We know from daily experience that some people have a better sense of smell than others. On the other hand, practice makes perfect. There is good empirical evidence that we can develop olfactory expertise by training our nose. We devised an apparatus capable of delivering different odors with high temporal precision within a sniff. For individuals curious to specifically train their olfactory temporal acuity, our apparatus could be helpful."

These lightning-fast olfactory capabilities are not interesting merely as biological trivia. Although less dependent on smell to process reality than other animals, humans still need it and will suffer from mental health disorders when that ability is impaired or eliminated through a condition known as anosmia. By learning more about how humans distinguish between different odors, scientists can ultimately illuminate the many mysteries about how humans are related to other animals… including our more nasally adept canine best friends.