One of the most difficult things for many managers to do is to evaluate potential new hires for our teams. Here’s why we often get it wrong.

You’d think as professionals who have led teams and risen through the ranks at work, most managers would have developed a fine judge of character and the ability to pick great hires. The trouble is, we all have our own biases and blind spots, and this all too frequently causes hiring blunders.

First impressions

We like to trust our gut. Studies have shown that the majority of hiring managers have decided whether they will hire someone within five to fifteen minutes of meeting them. This is even before any serious discussion about skills and credentials have taken place.

So, they’ve made that decision that could have a serious impact on the success of their company based on a first impression: mostly the candidate’s appearance, body language, and handshake. Only if you were hiring a model to specialize in non-verbal communications and shake people’s hands for a living would those be the most important credentials to consider.

They certainly don’t help you to select the most talented writer, accountant, or developer.

Candidate fatigue syndrome

This was first identified by researchers at Harvard. Candidate Fatigue Syndrome is an unconscious bias that recruiters often have towards the candidates they meet first, earlier in the day, and earlier in the week.

This is because interviewers start off their recruiting full of energy, wanting to like the people they consider for the job, and hopeful that each candidate will ‘be the one.’

The first person they interview has a clean slate. Interviewers evaluate them on their credentials. Those candidates who come after are compared negatively to earlier ones. Also, if a hiring manager ranked a candidate highly in the morning, they may feel that they are not being critical enough in their thinking if they appraise later candidates as highly, and force themselves to judge them more harshly.

This fatigue also applies to reading resumes. Candidates who apply early in the week have a statistically higher chance of being selected for an interview than those who apply later in the week. [See: New analyses of millions of applications reveals the best time to apply for a job]

So, if the best candidate for your job applies on a Wednesday, and the hiring manager has already read two days worth of applications, they might never be interviewed.

People value confidence over competence

Research published in the Journal of Personality and Social Psychology found that confidence in your abilities is more important than your actual talent when it comes to achieving higher professional and social status.

It makes sense that employers want to hire those candidates who demonstrate confidence in their ability to do the job. The trouble is that this gives an advantage to people who aren’t particularly talented but believe that they are or who are able to simply appear confident in social interactions. Extroverts fair better than introverts at job interviews, even for roles that they are less suited or qualified for. They’re just better at selling their accomplishments and talking about themselves in job interviews. (Similarly, this also gives narcissists and psychopaths a distinct advantage on the job market.)

“Our studies found overconfidence helped people attain social status,” said Cameron Anderson head researcher for this report. “Those who believed they were better than others, even when they weren’t, were given a higher place in the social ladder.”

What you can do about it

The trouble with blind spots is just that – you can’t see them. When evaluating candidates remember to go beyond your first impressions and really evaluate their communications skills, industry knowledge, and past work accomplishments. Don’t let the evaluation you made of an early candidate filter your impression of later ones. Consider each applicant by their own merits.

Introverts might come across as less confident in interviews, but that doesn’t mean that they are less talented. Unless the role specifically calls for an outgoing personality type, don’t make your hiring decision based on how self-assured the applicant seems. That assuredness can be misplaced.