I REMEMBER READING ABOUT an ingenious experiment on how hard it is to change people’s minds after they’ve already formed an opinion. The researchers took people who believed in the death penalty and people who didn’t, and showed them studies on the subject. Some studies were comparisons between two states of the U.S., one with the death penalty and one without, and how their crime rate differed. Other studies showed before and after crime rates of states who either did or didn’t have the death penalty and then changed.

The experimenters discovered that no matter which of the studies they showed people, their opinions did not change! Not only that, but whether they were for or against the death penalty, these people, all of whom viewed the same studies, became even more convinced of their original opinion. To all of them, the studies only reinforced their already existing opinions. What they did was find flaws — legitimate in most cases — in the studies, which gave them a good reason not to change their opinion. But they only criticized the study that did not support their opinion and they praised the study that did, pointing out all the (again, legitimate) reasons the study was a good one. But nobody changed their opinion.

This probably doesn’t surprise you. Most of us realize that people don’t like to change their opinions, and that they skew their perception of the events of the world to support their own opinions, and tend to criticize or be skeptical of unsupportive events.

Now here’s the point: People also do that with their opinions of you. When you first meet someone, they size you up and form an opinion about you. If you are cranky the first time you meet someone, they will tend to think of you as a grumpy person. If you are not grumpy the next time they see you, they usually won’t think to themselves, “Oh, I was mistaken.” No. They will think to themselves, “Oh, Mister Grumpy must have gotten some exceptionally good news today.” They will discount it if it is inconsistent with their first impression of you.

That’s why it often takes a long time to change someone’s first impression — and why it’s important to make a good one when you have a chance.