All of our senses come through in stereo. Except smell, arguable the most important one for drinking coffee. Our ears tell us which direction sounds come from, our sense of touch does the same with sensations, and we can tell what part of our tongue is lighting up with different flavors. Even the two little cameras that are our eyes work together to create a three-dimensional image. So why then, not our nose?
Well, it turns out that it actually may. As reported by Nature, a new study published in the journal Current Biology finds that the brain records smell information in different places depending on which nostril it came from.
Scent information, per the study, is received and processed in the part of the brain known as the piriform cortex, which spans both the left and right side of the brain. But how that information got processed—as being from the left or right nostril versus recognizing the nose as a singular input—remained unclear.
To find out, researchers from the University of Pennsylvania and the Barrow Neurological Institute “recruited people with epilepsy who were undergoing brain surgery” to take part in the study, though it had nothing to do with them having epilepsy. During their surgeries, these patients would remain awake while also having readings taken of their brain activity, including in their piriform cortex, making them ideal candidates for this sort of study.
When participants were given a smell input into a single nostril—via a tiny tube inserted roughly a centimeter into their nose—the side of the piriform cortex closest to that nostril lit up first, followed shortly thereafter by the other side. And when the smell input was given to both nostrils simultaneously, “both sides of the brain recognized the scent faster than either did when it was delivered through only one nostril,” suggesting a synergy to smelling something via both nostrils as opposed to just one.
In the real world, smells hit our nostrils in rather short order—so fast that the layperson would consider it more or less spontaneous—and when the researchers tested, participants weren’t able to assess from which nostril a smell was coming from and “were no better at giving the correct answer than if they’d guessed randomly.”
Though smelling in stereo didn’t appear to provide any sort of overt directional information to the participants, one neuroscientist suggests that it may still work to fact-check other sensory data by “compiling corroborating evidence about what we’re smelling so we can accurately identify odor sources around us.”
So while our noses can tell us that, yes, someone has started brewing up a fresh pot of coffee, it cannot, unfortunately, tell us where that brewing is currently taking place. We’ll just have to figure that out the old fashioned way with our eyes. Probably better to save all that nose power for the more important business of deciphering all that complexity going on inside the cup anyway.