Eventually, almost every interview turns into a question-and-answer session. You ask a question. The candidate answers as you check a mental tick-box (good answer? bad answer?).
You quickly go to the next question and the next question and the next question, because you only have so much time and there's a lot of ground to cover because you want to evaluate the candidate thoroughly. The more questions you ask, the more you will learn about the candidate.
Sometimes, instead of asking questions, the best interviewing technique is to listen slowly.
Duncan: He urged me to ask a good question, listen attentively to the answer, and then count silently to five before asking another question. At first that suggestion seemed silly. I argued that five seconds would seem like an eternity to wait after someone responds to a question. Then it occurred to me: Of course it would seem like an eternity, because our natural tendency is to fill a void with sound, usually that of our own voice.
Lehrer: If you resist the temptation to respond too quickly to the answer, you'll discover something almost magical. The other person will either expand on what he's already said or he'll go in a different direction. Either way, he's expanding his response, and you get a clear view into his head and heart.
Duncan: Giving other people sufficient psychological breathing room seemed to work wonders. When I bridled my natural impatience to get on with it, they seemed more willing to disclose, explore, and even be a bit vulnerable. When I treated the interview more as a conversation with a purpose than as a sterile interrogation, the tone of the exchange softened. It was now just two people talking...
Listening slowly can turn a Q&A session into more of a conversation. Try listening slowly in your next interviews. (Not after every question, of course: Pausing for five seconds after a strictly factual answer will leave you both feeling really awkward.)
Just pick a few questions that give candidates room for self-analysis or introspection, and after the initial answer, pause. They'll fill the space: with an additional example, a more detailed explanation, a completely different perspective on the question.
Once you give candidates a silent hole to fill, they'll fill it, often in unexpected and surprising ways. A shy candidate may fill the silence by sharing positive information she wouldn't have otherwise shared. A candidate who came prepared with "perfect" answers to typical interview questions may fill the silence with not-so-positive information he never intended to disclose.
And all candidates will open up and speak more freely when they realize you're not just asking questions--you're listening.