Your nose is a quick learner when it comes to the thousands of scents it encounters in its daily travels. Now, researchers have found that emotion plays a huge part when it comes to differentiating between similar smells.
Northwestern University researchers proved the surprising connection by giving volunteers electric shocks while they sniffed novel odours.
The study shows that a single negative experience linked to an odour rapidly teaches us to identify that odour and discriminate it from similar ones.
"It's evolutionary. This helps us to have a very sensitive ability to detect something that is important to our survival from an ocean of environmental information. It warns us that it's dangerous and we have to pay attention to it," said Wen Li, lead author of the study and a postdoctoral fellow at the Cognitive Neurology and Alzheimer's Disease Center at the Feinberg School.
In the study, subjects were exposed to a pair of grassy smells which were nearly identical in their chemical makeup and perceptually indistinguishable.
The subjects received an electrical shock when they were exposed to one scent, but not when they were exposed to the other similar one.
After being shocked, the subjects learned to discriminate between the two similar smells. This illustrates the tremendous power of the human sense of smell to learn from emotional experience.
Odours that once were impossible to tell apart became easy to identify when followed by an aversive event.
The research team also found specific changes in how odour information is stored in "primitive" olfactory regions of the brain, enhancing perceptual sensitivity for smells that have a high biological relevance.
The study is published in the journal Science.