The social psychology of this century reveals a major lesson: often it is not so much the kind of person a man is as the kind of situation in which he finds himself that determines how he will act.

— Stanley Milgram

In our quest to understand the world and navigate it successfully, we need to make use of the best ideas from different disciplines. Here’s a simple but useful concept from social psychology that will improve your understanding of human behavior (if you can keep it in mind).

It’s called the fundamental attribution error: the belief that how a person behaves is determined by “the kind of person they are.” In reality, decades of research have shown that situational factors play a major role in human behavior. In mathematical terms, it’s not “person = behavior,” it’s “person x situation = behavior.”

Even when we know better, it’s easy to make the fundamental attribution error. It’s a cognitive bias—a mistake our brains seem wired to make. But as with all cognitive biases, a little awareness can lead to better thinking, better decisions, and better outcomes.