The Interview Brainteaser and its Discontents - 7

by Joe Mabel

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(This is the continuation of an article about the use and abuse of brainteasers in job interviews.)

So are interview brainteasers ever a good idea?

Should an interviewer ever pose a brainteaser for a candidate? It will probably surprise you at this point that my answer is Yes. I see two valid uses for these questions:

Actually, when interviewing an experienced candidate, I almost never use a brainteaser as such; more commonly I pose a hypothetical situation such as trying to clarify a vague requirement brought by a client. I try to frame this as job-situation role-play, and to preface it with something like, OK, a client/ product manager has come to you and asked for this and you are trying to work out the details. Keep in mind that they may not really have a clear idea of what they really need and they may actually be asking for something that desn't make sense. Then I try to give an initial statement of a requirement that is not insane, but also not entirely well thought through, pretty much what I typically see from a marketing department or a client. When I can, I try to draw the example from an area in which the candidate claims expertise.

Along similar lines, if I pose a brainteaser in an interview, I first say something like, This next part of the interview is meant to try to learn something about how you think. Feel free to press me for any information you think would be useful to solve the problem, and I'll do my best to give it. I also say explicitly to the candidate that, as always when someone comes to you with a problem, I may not fully understand all the ramifications myself, so you should feel free to question my premises.

Also, if the candidate can't solve the problem, I would always tell him or her my proposed solution. Maybe my solution doesn't really work. Maybe the candidate has already thought of it and rejected it for a good reason. Maybe I'll find something out about the candidate if I give him/her a chance to poke holes in my thinking about the problem.

I am aware that some interviewers will pose a truly unsolvable problem if they believe that the key to a particular job is the ability to handle enormous stress. There is almost no chance that a person in a job interview will work out firmly and confidently in a matter of minutes that the problem is unsolvable, so all the interviewer will typically get to observe in this scenario is the candidate's behavior under exacerbated stress. (I have never actually used this technique myself, and I don't believe I would be comfortable doing so. Still, I would venture to suggest that if you are going to deliberately ratchet up stress in an interview, this should be done by a professional from a Human Resources department, not by the supervisor-to-be. The supervisor should get to play it straight and establish a rapport with their potential new subordinate. The stress interviewer had also better know in advance what he or she plans to say if the candidate calls the bluff and asks point blank, Do you believe your problem has a solution?)

In any case, a brainteaser well-used in an interview is, precisely, a tool to learn something about how someone thinks. It's not simply a tool to see how clever they are. Frankly, computer professionals are usually pretty good at gauging how clever someone is, and we don't typically need to pose brainteasers to do it. Conversely, few of us are experts at learning how someone else thinks, and throwing brainteasers at them is not, in and of itself, sufficient to learn that. Learning something relevant about a job candidate from watching him or her try to solve a brainteaser requires something that goes totally against our usual bias as technical professionals: it requires letting go of whether the person is headed toward what we believe to be the right answer and instead observing whether they are headed along a process that will often be useful in our organization.This is particularly tricky, because often the most useful person for us to find would be one whose intellectual processes do not simply duplicate our own, so our insight into those processes will probably be limited.

Dealing with this as a job candidate

Ha! So you think you can deal with this as a job candidate?

Sorry, I couldn't resist. I make no secret of the fact that I find brainteasers very hard to deal with as a job candidate in an interview, so maybe this is the blind leading the blind.

Sometimes I try to divert the subject, at least temporarily, to some of the points that are in this article, especially the point about wisdom vs. cleverness. After all, I'm looking for a good fit. Only a person who is open to that conversation is likely to be a good person for me to work for.

Ever since grappling with the Pirate, I make a point of asking for a little chill-out time before I start trying to solve this kind of problem. So far no one has said no. If they did, that would be a real indication I didn't want to work for them or with them. You might not want to be so explicit, but at least take a deep breath and give yourself a few seconds before starting.

Something I've never done, but I'm beginning to think is a good idea, and I might do it next time this arises: if the interviewer hasn't set a clear context, you might try to do so youself. Say something like OK, I've had the experience of people deliberately setting me an impossible problem in an interview and I've had the experience of someone being really bothered that I was probing around for hidden premises. Could you please set a context here and tell me if you are just looking for a clever solution, or if you want me to approach this the way I would if a client came to me with a feature request, or what?

Last, but not least (and a lesson I need to learn properly myself), don't just skip past a naive but wrong solution without mentioning it explicitly. Say, such-and-such looks almost like a solution, but I see a flaw in it. Maybe this is the solution the interviewer has in mind, but they didn't see the flaw, maybe it just gives them some clue to what wheels are turning in your head, but I don't see how it can hurt.

In any case, if someone posed me a problem I already knew, I would stick to a policy of don't lie, don't fake being someone you aren't, etc. Bad jobs are easy to find, and I believe that the only way to find a good one is to be real in the interview. However, a more cynical friend of mine has said that while she'd be upfront with a person she was going to work directly for, if someone more peripheral tossed out a brainteaser and she knew the answer, she ...could do a very realistic rendition of figuring it out on the spot [...] 'I've heard of this kind of problem before, I think it's probably like xyz, let's see if it is, blah, blah, blah. Oh, it's like with children, there's always one that you can't leave alone, so you bring it back and forth until you can keep it safe from itself and each other. Blah, blah, blah. Would that work, no. How about this. Oh, that's the answer?' I wouldn't whip it out all at once, because [...] he'd get tossing them out one after another and I'd want the interviewer to run out of time.

Of course, next time this arises, I now can say, Funny you should ask me that, I wrote an article you might want to read.

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Originally written: June 26, 2002
Article copyright © 2002 Joseph L. Mabel
All rights reserved.
Copyleft: With appropriate notification and appropriate credit, non-commercial reproduction is welcome: contact me if you have any desire to reproduce these materials in whole or in part.

Last modified: 26 June 2002

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