Is the old interview question about manhole covers narcissistic or revealing?

“Why are manhole covers round?”

That clichéd brainteaser is said to have become famous after appearing in a 2003 book that cataloged interview questions Microsoft would ask prospective employees to test their lateral thinking skills.

A number of “correct” answers have been suggested over the years.

However, recruiters are now questioning whether it was ever helpful in the hiring process, and psychologists have even pointed to malicious intent

Perhaps the most commonly cited response is that round lids cannot fall into the hole, while square lids would slide down if placed diagonally.

Others have argued that the round tubes they cover have the most structurally sound shape, and alternatively that a round cover never needs to be twisted to slide into a hole.

More abstract answers suggest that round covers can be rolled up, making them easier to move and use less material than square covers of the same width/diameter.

Jerry Seinfeld captured a manhole in NYC as part of a photo shoot by photographer Annie Leibovitz

The problem was just one in a series of interview questions that gained popularity in the early 2000s and were widely attributed to emerging tech companies.

Other questions may be along the lines of, “Why is a tennis ball fuzzy?” “How many cows are there in Canada?” or “How many piano tuners are there in the world?”

In William Poundstone’s 2003 book, “How Would You Move Mount Fuji?: Microsoft’s Cult of the Puzzle,” he writes, “Microsoft is known for its relentless refinement of form, subjecting candidates to a devastating barrage of brainteasers and ‘unanswerable’ questions to weed out the logical, motivated, imperturbable, innovative thinkers.’

In his 2003 book, How Would You Move Mount Fuji?: Microsoft’s Cult of the Puzzle, William Poundstone criticizes the way such questions are used by interviewers

Although the problems were originally linked to Microsoft and later to Google, the latter has increasingly distanced itself from it.

Ten years after Poundstone’s book, in 2012, Laszlo Bock, a senior vice president of people operations at Google, told the New York Times:

“On the recruitment side, we found that brainteasers are a complete waste of time. How many golf balls fit in an airplane? How many gas stations in Manhattan? A complete waste of time. They don’t predict anything. They mainly serve to make the interviewer feel smart.’

In a 2010 blog post, Gayle Laakmann McDowell, who had previously served on Google’s hiring committee, wrote about the manhole question: “This is a notorious interview question that has been so, very, very banned at both companies ever since.”

What makes it even worse is that in many cases the questions don’t make much sense and don’t have sensible answers either.

“For anthropologists studying the hiring rituals of the early twenty-first century, the strangest thing about these impossible questions would probably be: no one knows the answer,” Poundstone wrote.

A number of factors are likely to have influenced the shape of manhole covers and in particular they are not always round. In the UK many manhole covers are square.

In the UK and other parts of the world, some manhole covers are square

a 2018 paper in the International Association of Applied Psychology outlined a study of 736 adults to understand the effectiveness of the brainteaser interview question. Not only did it find the questions useless from a recruitment point of view, it even suggested they were asked out of malice.

“Results of a multiple regression, controlling for interview experience and sex, showed that narcissism and sadism explained the likelihood of using brainteasers in an interview,” the paper’s authors wrote.

While brainteaser interview questions seem to be out of fashion, interview guides from job boards like Indeed and Monster still advise candidates to be prepared.