If having an interviewer ask you a brain teaser question during a job interview feels like a (jerk) move, science backs up your intuition. How you answer a brain teaser says almost nothing about how you will perform on the job, but it says a lot -- and none of it good -- about the interviewer who enjoys asking the question.

Imagine you're in a job interview. The interview starts with an exchange of some of the most common interview questions and answers.

Then the interviewer shifts to asking a few of the most frequently-asked behavioral interview questions. Makes sense: Your achievements, your accomplishments... what you've done in the past is a reasonably reliable indicator of what you will do in the future.

But Then the Interviewer Asks a Brain-Teaser Question.

Maybe it's, "How many soccer balls would fit into the Empire State Building?" (A lot.)

Or, "Why is a manhole cover round?" *(Plenty of answers to that one; one good one is because a round cover can't fall through a properly-sized round hole.) 

Or, "If you have a 3-gallon jug and a 5-gallon jug, how would you measure out exactly 4 gallons?" (If you're into that kind of thing, the answer is below.)

If it feels like the interview just went off the rails, the researchers agree:

"Brain teaser interview questions are an example of aggressive interviewer behavior that lacks evidence for validity and is unsettling to job applicants... narcissism and sadism explain the likelihood of using brainteasers in an interview."

Narcissistic, sadistic... sounds like good descriptions of a (jerk) move to me.

To arrive at that conclusion, researchers gave study participants a list of interview questions to choose from. Some were conventional. Some were behavioral. And some were brain teasers.

The participants that chose brain teasers were more likely to be "socially inept, narcissistic, sadistic, and callous... and were much more likely to believe they could rely on their intuition to select the best candidate."

Which makes sense: A narcissist is a much more likely to think he can just "tell" who the best candidate is. (Hiring criteria? Who needs it.)

That's Why Google No Longer Uses Brain Teaser Questions

Companies like Facebook, Apple, LinkedIn, and Google famously (or infamously) became known for using brain teasers in interviews.

But then Google stopped.

Why? According to Lazlo Bock, the former VP of People Operations:

"On the hiring side, we found that brainteasers are a complete waste of time. How many golf balls can you fit into an airplane? How many gas stations in Manhattan? A complete waste of time. They don't predict anything. They serve primarily to make the interviewer feel smart.

"Instead, what works well are structured behavioral interviews, where you have a consistent rubric for how you assess people, rather than having each interviewer just make stuff up.

"Behavioral interviewing also works -- where you're not giving someone a hypothetical, but you're starting with a question like, 'Give me an example of a time when you solved an analytically difficult problem.' The interesting thing about the behavioral interview is that when you ask somebody to speak to their own experience, and you drill into that, you get two kinds of information.

"One is you get to see how they actually interacted in a real-world situation, and the valuable 'meta' information you get about the candidate is a sense of what they consider to be difficult."

In short, the right candidate possesses certain skills, certain experiences, certain attitudes... none of which are revealed by interviewer who ask questions like, "On average, how many cats are born in the United States every day?"

Maybe people who ask brain teasers think they're assessing a candidate's ability to reason. Maybe they think they're assessing a candidate's problem-solving skills. Maybe they think they're gaining insight into how a candidate thinks.

But science says all brain teasers reveal is that the interviewer enjoys putting people on the spot, and watching them squirm. 

Which is the last thing any interviewer should want to do.

And is the last way any company should want potential employees to feel.


How to measure out 4 gallons using a 3- and 5-gallon jug:

  1. Start by filling the 5-gallon jug.
  2. Pour 3 gallons from the 5-gallon jug into the empty 3-gallon jug.
  3. Pour out the water in the 3-gallon jug.
  4. Now you have 2 gallons in the 5-gallon jug, and an empty 3-gallon job.
  5. Pour those 2 gallons into the 3-gallon jug.
  6. Fill up the 5-gallon jug and pour 1 gallon into the 3-gallon jug that already has 2 gallons in it; that way you know you've poured 1 gallon out of the 5-gallon jug.
  7. Boom: 4 gallons remain in the 5-gallon jug.

And now you can solve that brain teaser.

But that ability indicates nothing about your skills, your experience, your accomplishments, your ability to lead and to follow...

... or about how well you can work with other people -- since no one ever does anything truly worthwhile on their own -- to develop and implement solutions to real problems.