Humans' compulsion to touch their faces may be part of a subconscious instinct to smell themselves.
(Inside Science) -- People touch their faces constantly. They do it without thinking, even now during the coronavirus pandemic, when health officials say not to. By some estimates, nearly a quarter of respiratory illnesses could be prevented by hand-washing, implying that people often contract such illnesses by touching their faces.
So why do we do it? One major reason may be to smell our hands, according to a hypothesis proposed today in the journal Philosophical Transactions of the Royal Society B.
It's well known that other mammals use smell to learn about themselves and their surroundings. But for decades, scientists have largely dismissed the importance of smell for humans, according to the authors.
Nevertheless, some studies suggest smell may be important for human social interaction. Using their noses, people may subconsciously decode messages about one another's health, moods and genetics.
In previous work, the researchers found that people more than doubled their rate of inhalation when they brought their hands to their faces. Touching was concentrated around and just below the nose.
"Or in other words, people are sniffing their own hands," wrote the authors. "Somehow, we are all looking at this behaviour, but mostly not seeing it."
In the same prior study, the researchers found that people waiting alone in a room spent 22% of the time with a hand near their nose. Other studies have reported that that medical students touch their faces 23 times per hour, and even doctors in a clinical setting touch their eyes, nose or mouth about 10 times an hour.
At this point, scientists can only speculate about why people might smell their hands so often. It may be a way of getting information about things one has touched, or checking to see whether one's own odors are offensive. On a subconscious level, write the authors, it may help people establish a sense of their own identities.
Whatever its function, the behavior is hard to miss once you are watching for it, the authors write. So next time you find yourself in a large audience (hopefully after the coronavirus crisis is under control), maybe take a look around and notice how many people are having a surreptitious sniff.
FAQs
It may be a way of getting information about things one has touched, or checking to see whether one's own odors are offensive. On a subconscious level, write the authors, it may help people establish a sense of their own identities.
Why does my child keep sniffing his hands? ›
A common, if not formally quantified behaviour, is placing the hand at an erogenous body location, and then sniffing it. This behaviour is often seen in public in toddlers or small children who have yet to internalize the associated social taboos.
What is the psychology behind sniffing? ›
The rapid modulation of sniffing upon inhalation of a novel odor or an irritating odor is evidence for an "olfactomotor" loop in the brain. In this loop, novel odor-evoked sniffing behavior can occur rapidly upon perception of a novel odor, one of interest, or an odor which is aversive.
Do people sniff their hands after shaking hands? ›
Some skepticism is probably warranted here, but new research suggests that humans subconsciously sniff their hands following a handshake in order to interpret chemical information about those around them.
What is constant sniffing a symptom of? ›
And if your immune system is down due to exhaustion, dehydration, stress, or an underlying health issue, it can take longer to get rid of your cold. However, a constant case of the sniffles may be a symptom of a sinus infection or nasal polyps.
Is sniffing part of autism? ›
Now, researchers reporting in the Cell Press journal Current Biology on July 2 have found that people with autism spectrum disorder (ASD) don't make this natural adjustment like other people do. Autistic children go right on sniffing in the same way, no matter how pleasant or awful the scent.
Is constant sniffing rude? ›
Sociology. In many cultures, blowing one's nose in public is considered impolite, and in reaction, people can make a habit of sniffling. In many other cultures, it is considered very impolite to sniffle.
What does sniffing mean in body language? ›
An important characteristic of sniffing is a closed mouth. This means you cannot talk when you sniff. It seems that this exactly reveals its function: sniffing is a signal you will not talk for a moment.
Is sniffing a bad habit? ›
A healthy person ingests around 1.5 litres of nasal secretions a day, so sniffing and swallowing isn't harmful. Any pathogens within the phlegm will be easily neutralised by gastric secretions.
Why do people sniff their arms? ›
Thus, it is not surprising that many people sometimes sniff at their bodies to check how they smell. Common examples are lifting the arm and sniffing the armpit to detect a sweaty smell or breathing into the hand to detect bad breath.
The psychologist Noam Sobel has shown that after shaking someone's hand, we will often give our fingers a good old sniff. Our brain subconsciously makes us do it.
Why does he smell his fingers after touching me? ›
If a guy wants to go down on you and he's not familiar with your hygiene habits yet, he might be checking to see what to expect. And when women do have a healthy vagin*l smell, we absolutely love smelling our fingers!
What is trimethylaminuria? ›
Trimethylaminuria, or fish odor syndrome (FOS), is a condition characterized by the presence of trimethylamine (TMA)—a tertiary amine whose odor is described as resembling that of rotting fish—in the urine, sweat, and expired air.
What are the symptoms of Trimethylaminuria? ›
The body releases the excess trimethylamine through sweat, urine, breath, and reproductive fluids, giving off a strong fishy odor. Many people with trimethylaminuria, particularly those with mild to moderate symptoms, will be able to reduce the smell with dietary and lifestyle changes.
Why do my hands smell so weird? ›
The potent odour residues on your hands come from sulfur molecules in foods. Due to our skin's natural oil, the sulfur molecules are easy to “stick” around your hands, which makes odours linger. An efficient exfoliating hand scrub helps loosen any build-up of sulfur molecules and dirt for a deeper cleanse.
What does sniffing your hand mean? ›
It may be a way of getting information about things one has touched, or checking to see whether one's own odors are offensive. On a subconscious level, write the authors, it may help people establish a sense of their own identities.
What does it mean when a child sniffs everything? ›
Answer: Some kids use smell to calm themselves down, especially if he's bothered by sound or other environmental things. In the short term, I would set up a sensory diet to include scented markers, scented clay, etc., to meet that need, along with some good calming “red arrow” activities to settle his nervous system.
Why does my 6 year old constantly sniff? ›
Two types of tics are associated with Tourette syndrome: Motor tics: These are sudden, apparently uncontrollable movements such as exaggerated eye blinking, grimacing, head jerking, or shoulder shrugging. Vocal tics: These include repeated throat clearing, sniffing, or humming.
Why is my 5 year old sniffing so much? ›
You are concerned as your 5 year old has started dry sniffing on a regular basis. Its most likely that this is due to habit, rather than a physical condition. A good approach to this kind of behaviour is often to ignore the behaviour, and try to avoid drawing attention to it.
