Why do we get annoyed? Science has irritatingly few answers.

Picture yourself at a crowded airport departure gate. Your flight is 20 minutes late, although the illuminated sign still says On Time.

The woman on your left is noisily eating something that smells awful. The overhead TV is tuned to a celebrity gossip show, a relentless stream of Bieber after Gwyneth after Miley, plus countless Kardashians. The man to your right is still braying into his cell phone, and the traveler next to him is preparing to kill time with … wait, is that a toenail clipper?

Unless you are saintly or unconscious, a few things in that description—or many things, or all the things—are likely to really bug you. We know an annoyance when we experience it. But from a scientific perspective, just what makes something annoying? Are some things universally annoying, while others are specific to an individual? And does research offer any advice for preventing life’s annoyances from making our heads explode?

The answers to those questions are: We don’t know, we don’t know, and no.

Annoyance may well be the most widely experienced and least studied of all human emotions. On what do I base that assertion? About a decade ago, fellow journalist Flora Lichtman and I made that claim in a book called Annoying: The Science of What Bugs Us—and in the intervening years, no one has challenged us.

After we noted the lack of studies on this topic, did scholars step up to the plate? Did even one university create a Department of Annoyance Science … endow a Distinguished Chair for Continuing Research Into Annoyance … or offer a major in annoying studies? No. Nothing. Nada. Zilch.

It’s not as if the proliferation of things that drive us crazy has slowed in the past 10 years. Quite the opposite. Consider the explosive, ineluctable growth of Twitter: Once a seemingly benign social media platform, it now intrudes on every sphere of existence, tempting us to address matters we should rightly have no interest in. There’s the pandemic of social media influencers, the unwelcome bounty of robocalls, and the invasive assault of personalized and pop-up ads. There’s my personal favorite at the moment: electric scooters, threatening the well-being of pedestrians when the contraptions are moving and forming sidewalk stumbling hazards when they’re parked. And the list goes on and on: See responses to National Geographic’s online survey about what annoys us below.

What makes something annoying? Our analysis came up with three qualities that seem essential.

First: It must be noxious without being physically harmful. A housefly buzzing around your head is unpleasant, but it won’t kill you.

Second: It must be unpredictable and intermittent. The loud ticking of an alarm clock or the odor of a cat litter box may at first be annoying, but with constant exposure over time, it ceases to be noticeable. Psychologists’ term for this gradual tolerance of a stimulus is habituation. Yet when an unpleasant noise or smell comes and goes, it becomes annoying each time it shows up.

The intermittent nature of annoyances makes them hard (if not impossible) to anticipate and thus to prepare a defense against. If you know you’re going to be stuck in traffic, you might be able to take it in stride or bring along a distraction. But when the slowdown is unexpected, it gets to you before you can stop yourself.

Third and finally: To be truly annoying, something has to persist for an uncertain period of time. A flight that’s delayed an hour is a bother, but tolerable, so long as it really is just an hour. A flight that’s delayed and delayed and delayed, with no explanation and no end in sight, is excruciatingly annoying.

Now it could be that you read that last paragraph and said to yourself, Wait a minute—a delayed flight isn’t that annoying. If I have a good book to read, I don’t mind waiting in an airport. That speaks to another key feature of annoyance: It’s “highly context-​specific,” says Russell Shilling, the American Psychological Association’s chief scientific officer. “There is a lot of variability between individuals and cultures.” For example: The same kind of intermittent, unexplained delays that might exasperate airline passengers are just part of the job for a pilot.

As for an example of annoyances varying by culture: If a U.S. family visits a beach with only one other family present, they’ll tend to throw down their towels a discreet distance away. In some Mediterranean countries, plopping down right next door is the norm, but that would cause many Americans to seethe.

Shilling says individual variability is one reason it’s so hard to tease out the universal properties of annoyances. But that individuality may be useful in certain settings. A psychiatrist friend of mine notes that while her patients may be reluctant to talk about their private dark thoughts, they have no problem railing about the people and situations that annoy them. Encouraging people to share their annoyances could be an easier way to open a window into their psyches.

An intriguing thing about annoyances is how they appear to change over time. A decade ago, our research led us to conclude that one of the most annoying things in the world was listening to someone else’s loud cell phone conversation. We hypothesized that the reason it was so annoying is that our brains are naturally predisposed to painting a complete picture of reality, but when you only hear half of a conversation, that’s not possible.

Then, cell phone conversations seemed annoying only to the people not on the phone. Today it’s the call recipients that seem to be getting annoyed. I’m not talking about receiving a robocall. I’m talking about the 20-something who recently told me that an unexpected call, even from a close friend, is annoying. The thinking seems to be, Why call when a text will do? Or even, You should have texted to ask if you could call …

If there are some things in life that are universally annoying, human physiology may provide clues to help us define them. We have a variety of reflexes that kick in to protect us from truly dangerous stimuli. Gagging could prevent us from ingesting something that’s potentially poisonous. The blink reflex protects our eyeball if an object is heading toward it. There’s even something called the middle-ear muscle reflex that protects our eardrums from damage from truly loud noises.

The reason someone with a cloying cologne is annoying may derive from the gag reflex. Likewise our response to a vuvuzela, that deafening plastic horn, may be a vestige of our natural protections from any loud noise.

Another place to look for clues to the fundamental nature of annoyance is to study people with conditions that make them particularly prone to annoyances. Just as studying people with hypercholesterolemia—dangerously high cholesterol—led to the first drugs for lowering cholesterol, so might studying people with the disorder misophonia lead to ways to help keep us from becoming annoyed.

According to the National Institutes of Health’s Genetic and Rare Diseases Information Center, people with misophonia have an extreme emotional response to sounds that others find innocuous. Just hearing someone breathe or yawn or chew a potato chip can generate severe agitation in susceptible individuals. If researchers find more ways to calm those people, there may be some benefit for all of us.

In the decade since the book came out, I’ve thought a lot about what makes people, things, and situations annoying, and what any of us might do to inoculate ourselves against becoming annoyed. The answer’s actually surprisingly simple: All you have to do is