You see it, you want it. No, not to buy it. To taste it. It’s a weird, primal urge that doesn’t really go away once you hit adulthood, though we’re better at hiding it than toddlers are. We’ve all been there—holding a smooth river stone or a piece of particularly clicky plastic and thinking, just for a split second, that we should put it in your mouth just to see what happens. It sounds ridiculous when you say it out loud. But it’s a fundamental part of how humans actually process the world around them.
Biologically, your mouth is packed with more sensory receptors per square millimeter than almost anywhere else on your body. It’s a high-definition scanner for the physical world. While we mostly use it for eating and talking, the brain never quite forgets that the tongue is the ultimate arbiter of texture and density.
The Science of Oral Exploration
Why do we do it? Evolution.
Developmental psychologists, like those who follow the work of Jean Piaget, note that the "sensorimotor stage" is where it all begins. For a baby, the eyes aren't great yet. The hands are clumsy. But the mouth? The mouth is precise. A child will put it in your mouth—referring to anything from a set of keys to a dust bunny—because the trigeminal nerve provides a massive amount of data to the brain about whether something is hard, soft, cold, or potentially food.
Interestingly, this doesn't totally vanish. We just transition into "socially acceptable" versions of oral fixation. We chew on the ends of pens. We gnaw on our fingernails when we're stressed. We fiddle with the drawstrings of a hoodie between our teeth. Dr. Ian Blank, a researcher who has looked into sensory processing, suggests that these oral behaviors are often self-soothing mechanisms. They ground us. When the world gets chaotic, the tactile feedback of something against our teeth provides a strange, rhythmic comfort.
📖 Related: Why the 24 pack of coca cola cans is actually the weirdest math problem in your grocery aisle
Pica and the Edge of Normalcy
There is a line, though. Most of us just have a passing thought or a mild habit. But then there’s Pica.
Pica is a psychological disorder where people have a persistent craving to eat non-nutritive substances. We aren't talking about accidentally swallowing a piece of gum. We're talking about ice, dirt, clay, or even metal. It’s often linked to iron deficiencies or pregnancy. When your body is screaming for minerals it isn't getting, the brain's logic centers sometimes short-circuit. It tells you to put it in your mouth, specifically targeting things like soil because, deep in our evolutionary lizard brain, that's where minerals come from. It's a fascinatng, albeit dangerous, example of how the body tries to heal itself through taste when the conscious mind doesn't know what's wrong.
The "Forbidden Snack" Phenomenon
If you spend any time on the internet—specifically places like Reddit or TikTok—you’ve seen the memes. Tide Pods were the dark version of this, but it goes much further. People post videos of "forbidden snacks."
What are they? Usually, things like:
- Clear, jiggly industrial lubricants that look like high-end jelly.
- Polished gemstones that resemble hard candy.
- Expanding foam that looks like sourdough bread.
- Chunks of colorful insulation that look like cotton candy.
There is a genuine psychological tension here called "affordance." In design theory, an affordance is a property of an object that tells you how to use it. A handle "asks" to be pulled. A button "asks" to be pushed. Some objects, because of their color, shimmer, or squishiness, "ask" to be tasted. When you see a D20 die that looks exactly like a raspberry gummy, your brain experiences a brief "glitch." You know it's plastic. You know it will hurt your teeth. But the visual signal is so strong that you still feel that ghostly tingle in your jaw. You want to put it in your mouth just to resolve the sensory conflict.
Cultural Taboos and the Mouth
The mouth is a gatekeeper. In many cultures, what you put in your mouth defines your status, your religion, and your health. There's a reason "disgust" is one of our strongest emotions. It’s a survival mechanism designed to keep us from ingesting pathogens.
But humans are also incredibly adventurous. We’ve turned the act of putting things in our mouths into a multi-billion dollar industry that goes way beyond nutrition. Think about wine tasting. You aren't just drinking; you’re aerating the liquid, coating your tongue, and looking for "mouthfeel." That term—mouthfeel—is used by food scientists to describe the physical sensations of food, separate from the actual flavor. It’s the crunch of a chip or the velvetiness of chocolate. Without that tactile satisfaction, the "taste" feels incomplete.
The Dangers of the Habit
Look, we have to be real here. Choking is a leading cause of accidental death, especially in children. The "Small Parts Test" used by toy manufacturers is essentially a plastic tube that mimics the size of a child's throat. If a toy fits in that tube, it’s a hazard.
As adults, our risks are different. We deal with dental erosion and "cracked tooth syndrome" from chewing on ice or pens. Dentists like Dr. Steven Lin often point out that the human jaw is capable of exerting incredible pressure—up to 200 pounds on the molars. When we put it in your mouth—whether it's a bottle cap we're trying to unscrew or a sewing needle we're holding while we work—we're playing a high-stakes game with our enamel.
How to Manage the Urge
If you find yourself constantly needing to chew on things or if you're worried about a child's habits, there are actually "chewelry" options. These are medical-grade silicone necklaces designed for people with ADHD, autism, or general sensory processing needs. They provide that oral input without the risk of breaking a tooth or ingesting toxins.
Honestly, it's about mindfulness. Next time you find yourself about to chew on a plastic cap, ask yourself if you're actually bored or just thirsty. Often, the brain confuses the need for sensory stimulation with a need for hydration.
👉 See also: Shampoos That Do Not Contain Sulfates: What Most People Get Wrong
Practical Steps for Sensory Health
Stop treating your mouth like a third hand. It’s hard, I know. But your teeth aren't tools.
If you're a "chewer," try switching to sugar-free gum with xylitol. It keeps the jaw busy and actually helps remineralize your teeth. If it's a child you're worried about, do the "toilet paper roll test." If an object can fit through a cardboard toilet paper tube, it’s too small for a young child to be playing with unsupervised.
The urge to put it in your mouth is human. It's how we learned to navigate the world before we had words. But now that we have words—and dentists—it’s probably better to stick to things that are actually meant to be eaten.
Actionable Insights for Daily Life
- Audit your desk: If you have a habit of chewing pen caps, replace them with metal pens or use "chewable" toppers specifically designed for focus.
- Check your minerals: If you have an overwhelming urge to eat ice (pagophagia) or dirt, see a doctor for a blood test. You might be low on iron or zinc.
- Sensory breaks: If you feel "fidgety" in your mouth, try a strong flavor like a sour lemon or a spicy mint. Sometimes the brain just needs a "reset" of the sensory receptors.
- Safety first: Keep high-risk items like button batteries and small magnets (which are incredibly dangerous if swallowed in pairs) far away from surfaces where people eat or drink.