I have seen a lot of comments about good interview questions and puzzles to require potential developers to solve during the interview process.

I have personally had several interviews in which the interviewer has asked me to write some piece of code or solve a problem during the interview, and I have always performed very poorly in these "tests".

The reason is simple, as a developer who spends my days talking to computers, I find I have to prepare myself and "switch gears" to be in "interview mode". I prepare myself to make a good impression.

When I'm programming, I'm very focused and am totally different from when I'm being "interpersonal". I just can't get into "the zone" when I'm also having to be a charming and witty potential employee.

I feel that by asking a developer to prove his skills during an interview, all you're doing is finding out if they can code under pressure, and at the drop of a hat. It has almost no ability to determine how you would perform in a "real life" development situation.

Maybe, if you're looking for someone that can code and chat at the same time, i can see how that would be beneficial. But I think you overlook potential candidates that simply do not perform well in such an artificial environment.

While I appreciate that a potential employer wants to see what I can do, I don't think an interview is the place for such a test. I mean, suppose a job for an over the road trucker required that you drive while being interviewed. How does that really end well?

So I'm curious as to what others think about such situations. Have you failed interviews because you were not in the right frame of mind? Have you failed to make a good interpersonal impression because you were too distracted trying to solve the problem?

If you're a hiring manager, or someone that gives interviews, do you even think about such things? Is it really important that someone perform well in an interview?

EDIT:

To clarify, I'm not against testing applicants. My concern is about testing during an interview.

See also: What are the pros and cons for the employer of code questions during an interview? looking at this from the interviewer's point of view.