Those who are born into upper class families start out with tons of advantages, including money, connections, and better educational opportunities. But according to a new Stanford study, they also enjoy another powerful but less discussed leg up in life--unearned overconfidence.

That wouldn't matter if no one was buying their bluster, of course. But the study also shows just how easily many of us are taken in by charisma and confidence. Chances are excellent you're missing out on great talent because of this bias

Overconfidence pays. 

It may not be news to you that people often mistake confidence for intelligence. Previous research points in this direction, and many of us have life experiences that indicate as much as well. But the new study by Stanford Business School's Margaret Neale and collaborators offers a particularly detailed picture of the phenomenon. Depressingly, it also shows that the rich benefit most from our tendency to defer to the loudest person in the room. 

For instance, in one experiment the researchers looked at 150,000 real life entrepreneurs applying for small-business loans in Mexico. As part of the loan process, the applicants were asked to perform a simple memory test. Those with a higher income were sure they'd done especially well on the task. They hadn't. 

Think it's just Mexico? In another experiment, University of Virginia undergrads took a difficult trivia quiz. Those who came from families with higher incomes were equally sure they'd outperformed others on the test. Again, they did no better than average. 

Taken together, these experiments are pretty strong evidence that overconfidence and privilege frequently go together, but are those exposed to this bluster actually falling for it? To see how overconfidence affects others' perceptions, the researchers had outside observers evaluate the same undergrads in mock job interviews. The observers rated the more confident students as smarter and more hirable despite their being no objective evidence to suggest this. 

How to hire the best, not the best talkers. 

The takeaway here is as clear as it is depressing--being overconfident generally pays off, and it's those who already have the most advantages who often benefit. That's annoying for anyone who thinks there should be a level playing field in life, but it's also a problem for entrepreneurs who want to hire the best talent, not the smoothest talkers

"We really need to be more discerning about confidence," study co-author Peter Belmi commented to Insights by Stanford Business. "Just because somebody can speak very assertively, or can speak in a very confident way, doesn't mean that person's smart."

Just being mindful of our propensity to be seduced by bluster can be helpful (as can being aware of other signs someone is genuinely smart and not just confident), but the authors also suggest that, when it comes to job interviews, leaders follow the same age-old advice given to writers: Show, don't tell. 

For example, don't ask a job candidate to explain a time he or she shined in her role. Instead, give everyone a short assignment that tests their ability to actually shine at the required tasks. If you evaluate on confidence, you're likely to choose well-heeled slick talkers over those with the skills to do the job.