The findings suggest that the brain does make use of the different arrival times. When an odour was delivered to a single nostril, the side of the brain closest to that nostril reacted first, and a reaction then followed in the opposite side of the brain. “There seem to be actually two odour representations, corresponding to odour information coming from each nostril,” [neuroscientist Naz] Dikecligil says.

When the researchers provided a scent to both nostrils simultaneously, they saw that both sides of the brain recognized the scent faster than either did when it was delivered through only one nostril. This suggests that the two sides do synergize to some degree, even though one lags behind the other in encoding a scent, Dikecligil says.

— Read more in You smell your coffee in stereo: the brain records an odour’s spatial information at Nature.