CHICAGO (AP) - It all seems so unbelievable. How could a big-time college football player such as Manti Te'o have a girlfriend he's never actually met?

Yet experts say what the star Notre Dame linebacker says happened to him happens much more often than people care to admit.

Psychologist Robert Epstein says it's a mistake of human nature known as ``confirmation bias.'' We ignore good advice and miss red flags, so we can continue believing in something we want to be true.

It's a mistake made by people online since mingling began in Internet chat rooms more than 20 years ago.

And while Twitter and Facebook have made such casual contact online easier, they also have allowed impostors to create intricate personas that make it that much easier to delude ourselves.