Why Do People Behave the Way They Do?

The man in front of you at the checkout is shouting at a teenager on the till. A friend hasn’t replied to your message in three days, though she’s posting online. Your neighbor waves at you every morning and has never once asked your name.

Every day we watch people do things that puzzle, annoy or hurt us, and we automatically come up with explanations. He’s rude. She doesn’t care. They’re unfriendly. Often those explanations are wrong, or at least incomplete.

This site is about the question in its name: why do people do that? This guide is the starting point. It looks at the main forces that shape behavior, the mistakes we make when we try to read other people, and how a better understanding helps you respond in ways that work.

Behavior is person plus situation

In the 1930s, the psychologist Kurt Lewin summed up a big idea in a small formula: behavior is a function of the person and their environment. Both matter, and they interact.

The person side includes temperament, personality, values, past experiences and the habits someone has built over a lifetime. Some people are more anxious, more outgoing, more sensitive to criticism or more driven to be in control.

The situation side includes everything around them in the moment: stress, tiredness, hunger, who is watching, what’s at stake, the rules of the place they’re in. The same person can be patient at home on a Sunday and short-tempered at work on a Monday.

The man at the checkout may be a rude person. He may also have just come from a hospital, be running late to collect a child or be in pain. Most of the time, we only see the behavior, not what’s behind it.

The mistake we all make

Social psychologists have shown again and again that we tend to explain other people’s behavior by their character, while explaining our own by our circumstances. When someone cuts you off in traffic, they’re a selfish driver. When you cut someone off, you were late, the sign was confusing, they came out of nowhere.

The psychologist Lee Ross called this the fundamental attribution error. It’s not a flaw of a few people; it’s a basic feature of how human minds work. We see other people’s actions clearly and their circumstances dimly. With ourselves, it’s the other way round.

Knowing about this habit doesn’t make it go away, but it gives you a useful question to ask whenever someone’s behavior bothers you: “What situation might make a reasonable person do this?” You won’t always find a good answer. But you’ll find one more often than you expect.

What behavior is usually for

A helpful way to understand puzzling behavior is to ask not “what’s wrong with them?” but “what is this doing for them?” Most behavior, even irritating behavior, is an attempt to meet a need. A few needs come up again and again.

Safety. People who feel threatened, physically, emotionally or socially, act to protect themselves. Defensiveness, lying, withdrawal and aggression are often forms of self-protection.

Belonging. Humans are social animals, and the need to be accepted runs deep. Gossip, people pleasing, fitting in and fear of rejection all come from here.

Status and respect. People care a great deal about how they’re seen. Bragging, one-upping, interrupting and never admitting mistakes are often about protecting or raising status.

Control. Uncertainty is uncomfortable. People who feel out of control often try to control what they can, which may be other people.

Avoiding pain. Many behaviors are ways of escaping discomfort: avoiding a hard conversation, ghosting instead of explaining, lying to avoid a fight.

When you can guess the need, the behavior usually makes more sense. It doesn’t make it acceptable. But it points you toward a response that addresses the real issue.

Why habits matter so much

A lot of behavior isn’t decided at all. It’s habit. People do what they’ve always done, often what they learned growing up or in places where it worked.

Someone who grew up in a family where nobody apologized may find “sorry” almost impossible to say. Someone who learned that the way to be heard was to talk loudest will keep doing it. Someone who was punished for showing anger will express it sideways.

This is one of the most hopeful ideas in psychology, because habits can change. But it’s also a reason for patience. When you ask someone to stop a long-standing behavior, you’re often asking them to override years of practice.

The everyday behaviors that puzzle us most

Each of these has its own guide on this site.

Lying

Most people lie a little, about small things, most days. A smaller number lie a great deal. Understanding why makes it easier to know when to let it go and when it matters. See Why Do People Lie?.

Ghosting

Disappearing without a word, from a date, a friendship or a work conversation. It’s usually about avoiding discomfort, not about you. See Why Do People Ghost?.

Judging others

Quick, harsh judgments about people we barely know. We all do it, and it often says more about the judge than the judged. See Why Do People Judge Others?.

Talking only about themselves

The friend who turns every conversation back to their own life. See Why Do Some People Only Talk About Themselves?.

Never apologizing

People who explain, deflect or change the subject, but never quite say sorry. See Why Do Some People Never Say Sorry?.

How understanding helps

Understanding why someone behaves the way they do is not the same as excusing it. You can understand exactly why a friend lies and still decide you can’t trust them. You can see that a relative’s criticism comes from anxiety and still ask them to stop.

What understanding does is change your response. It turns a vague feeling of “they’re impossible” into something specific you can work with. It helps you choose battles. It takes some of the sting out, because behavior that comes from someone’s own fear or habit is less personal than it feels. And it often makes you kinder, which, as it happens, tends to bring out better behavior in others too.

A few habits help in everyday life:

• Pause before judging. Ask what situation might explain what you’re seeing.
• Look for the need. What is this behavior getting them?
• Respond to the behavior, not the person. “You interrupted me” is workable. “You’re rude” isn’t.
• Say what you need, simply. Most people respond better to a clear, calm request than to hints or accusations.
• Watch for patterns, not single moments. Everyone has bad days. Patterns tell you more.

And of course, the same ideas apply to us. Most of the behaviors in this guide are ones we all show sometimes. Understanding other people tends to make us a little more honest about ourselves.

If the behavior that puzzles you happens mostly at work, at home with a partner or with relatives, our other guides go deeper: How to Deal With Difficult Coworkers, Understanding Your Partner’s Behavior and How to Deal With Difficult Family Members.