The old saying goes that you never get a second chance to make a . Why would that be? Surely, getting to know someone ought to give you more valuable information about who they are than just a brief encounter. And clearly first impressions can be mistaken. A favorite storyline in the featured wedding in the Sunday New York Times is that the couple didn't like each other when they first met even though their friends were all convinced that they were right for each other.

What is going on with these snap judgments?

A lot of recent research has begun top play up the accuracy of judgments that get made quickly based on a sliver of information. This work, popularized by Malcolm Gladwell's book Blink suggests that there are many cases in which these snap judgments are accurate.

A paper by Daniel Ames, Lara Kammrath, Alexandra Suppes, and Niall Bolger in the February, 2010 issue of and Social Psychology Bulletin looked at people's and accuracy when making judgments about personality characteristics of others.

In these studies, participants got to see photographs or short videos of real people. The authors had also done personality assessments of these people to find out their values on the personality attributes ( , , , , and ). For each of the people that a participant judged, they saw a picture or video, and filled out a brief personality questionnaire for them. Then, they judged how confident they were in their judgments.

The results suggest that people are moderately accurate at predicting a few personality dimensions based on small amounts of information. For example, when seeing a brief video, participants showed some accuracy predicting a target person's agreeableness, conscientiousness, and emotional stability, but not their extraversion or openness.

Although they were able to predict these dimensions to some degree, there was quite a bit of disagreement between people. That is, the judgments were very variable. In addition, a person's confidence in their judgment about someone else had almost no relationship at all to their accuracy. There was a slight tendency for people to be correct that they felt that they had no good basis for making a prediction, but when people were confident that they could make a good prediction, that did not signal that they actually could make a good prediction.

In addition, people who generally have high confidence in their intuitions were more confident in their judgments than those who like to think a lot about making judgments. But this trust in did not lead to more accurate judgments.

So, what does this mean?

When getting to know other people, we ought to treat our first impressions with caution. It really does take a while to get to know people, and those first impressions are often flawed.

Worse yet, they can create a self-fulfilling prophecy. Those initial impressions can affect how you treat people you have just met. And your treatment of them will affect the way they react to you in return.

Finally, remember that your confidence in your beliefs about people you just met doesn't really reflect how accurately you have gotten to know them.