Have you ever arrived home from vacation, only to have your nostrils assaulted as soon as you open the door?
“Why does my house smell so bad?” you might say, as you furiously scramble to find the source. What you may not realize, however, is that maybe your house always smelled bad.
Perhaps you never noticed it, because you’re so used to it — an even more terrifying thought. But as it turns out, that’s exactly what happens.
It’s called “sensory adaptation,” something Pamela Dalton, a cognitive psychologist at Monell Chemical Senses Center, has devoted decades of her career to studying this phenomenon.
She explains it by using the example of a chemical air freshener. When you first start to use one, the odor molecules travel through your nose and hits your odor receptors, which then send signals up to your olfactory bulb in the brain’s limbic system. This is the part of your brain associated with emotion and behavior, but it’s also used to detect incoming threats.
Obviously, a chemical air freshener poses no threat, and your brain recognizes that, so almost immediately, it starts to switch off the receptors in your nose – and that’s why the intensity of the smell starts to fade quickly. But why does this happen? Is it to preserve resources?
Well, we’re not exactly sure. But the leading theory says that by adapting to the smells in our environment, we can quickly detect new changes that could be potentially threatening.
So if your house was musty, for example, and that would be all you ever smelled and you’d be unaware if something else in your house, started rotting.
It makes sense from an evolutionary standpoint. Bu then again, why is this phenomenon exclusive to our sense of smell? It’s not like staring at something for a long time makes you go temporarily blind.
And while you can start to tune out noises after a while, you” snap out of your reverie when someone comes up to you and starts talking. With smells, however, you can’t really do that.
Once you’ve grown accustomed to the way something smells, the only way to actively detect it after a while is to leave the area and come back.
Interestingly, though, there is another way to slow down the adaptation process, and that’s physical activity – or really, anything that increases blood flow. Dalton points out that scientists who work at perfumeries – will sometimes run and up and down stairs, to regain their sense of smell.
Although perfumery is probably one of the few careers where you’d need to actually smell things all the time, it is worth noting that being overly concerned about smells – can actually make you more sensitive TO them.
In her interview, Dalton recalls a study in which she exposed 3 groups of people to the same scent – telling the first group it was a “rainforest extract,” the second group that it was a standard scent used by her lab, and the third group, an industrial solvent.
Sure enough, the people who thought they were smelling industrial solvent, were also the slowest to adapt to the scent. Which coincides with the fact that we adapt to smells we consider non-threatening.
It really is quite amazing just how efficient the human body is.