Why are manhole covers round? How many barbershops are there in San Francisco? Job seekers are increasingly being asked questions like these at job interviews. And according to a study from San Francisco State University, they're none too happy about it.

First popularized by Microsoft in the 1990s, puzzle questions are most common in the financial and technical fields, where interviewers see them as a good way to measure creativity, flexibility, critical thinking and the ability to work in unusual and sometimes uncomfortable situations. But as the researchers found, other people tend to see the questions as unfair and unrelated to job performance.

Some employers turned to puzzle questions because they felt that job applicants were too well coached on how to respond to traditional questions, having found good answers through career coaches, websites and other sources.

The researchers videotaped mock interviews that used puzzle questions and others that used questions more traditionally asked of job seekers, such as those about an applicant's past job performance and goals. They then had 360 undergraduates watch either a puzzle interview or a more traditional one and rate both the interview's content and the job applicant's performance.

The puzzle interviews got consistently negative ratings from the students, even when it was made known that the interviews were for jobs that place a premium on a puzzle solving skills, such as software engineer or financial analyst.

On the brighter side, most of the students said that applicants performed better in the puzzle interviews than in the traditional interviews.

Some employers turned to puzzle questions because they felt that job applicants were too well coached on how to respond to traditional questions, having found good answers through career coaches, websites and other sources. But job seekers can still do this today for the puzzle questions. Sites like mytechinterviews.com maintain a growing collection of puzzle questions and answers.

Chris Wright, the psychology professor whose team conducted the study, thinks that graduates need to be prepared to face puzzle questions because there's a good chance they'll have to answer them at a job interview. Wright's advice: expect the unexpected and be aware that you might get an off the wall question. Wright also says that it's helpful to realize that there's often no single right answer to a puzzle question and that the interviewer may be more interested in gauging your thought process.

Wright thinks that these questions may end up backfiring. First there's the possibility that applicants may decide that the companies who ask these questions are undesirable employers, though in today's job market that might not be very meaningful. But Wright also speculates that questions seen as unfair or irrelevant to a job could lead to lawsuits, against the companies that ask them.

And Wright wonders if these questions really measure anything meaningful. He thinks that if they're designed to measure intelligence, or an aspect of it, there are probably better tools available to an interviewer. But that's no comfort to those being interviewed, who still need to answer the questions.

An article on the study was published online by the Journal of Applied Social Psychology on October 15, 2012 and will also appear in a future print issue of the journal.