Good News: your first impressions are usually pretty accurate .

Bad News: whether they are wrong or right, first impressions affect us in a big way and we are slow to change them .

Sam Gosling is about as close to Sherlock Holmes as you can get. He's a personality psychologist at the University of Texas and author of the book Snoop . Here's Sam:

First impressions are often quite helpful but you have to be willing to update them quite rapidly. That's what's very hard to do.