A lousy interviewee usually won't land a job, especially in this job market. But according to a recent study, employers may be missing out on strong candidates if they base their hiring decisions solely on impressions from interviews.

The study, conducted by the University of California at Berkeley and published in the Journal of Personality and Social Psychology, tested the correlation between confidence and competence, to determine whether or not those individuals that came across as the most confident were actually the most skilled.

In one study, researchers arranged four-person groups to work together on math tasks. The dominant people took over even though they were no more quantitatively skilled than the others. They were perceived as highly competent, even though they did not offer any more accurate answers than other members.

These individuals "come across as highly competent because they speak with more confidence, assert their opinions often and with the body language that conveys certainty," says study co-author Cameron Anderson, an associate professor of organizational behavior.

In a hiring context, Anderson says, this insight is valuable. "Just because a person seems certain in their opinions, ideas, or abilities does not mean that they are actually better than others or that they will be better performers," he says.

As diagnostic tools, interviews "do not allow for an accurate test of competence or potential," he says. "Candidates who might seem talented because they are self-assured might turn out to be incompetent. At the same time, candidates who seem to lack talent because they are quieter and more reserved could be extremely sharp and potentially strong performers."

As much as possible, Anderson recommends collecting objective data about a person's true capabilities before making a decision.