Silence of the Interviewer
Silence can be a valuable tool to an interviewer when used correctly in an interview. Remember that when a period of silence develops in an interview, the pressure lies heavily on both you and the candidate to break that silence. Let the candidate break the silence not you!
The first time to use silence is after you ask a question. When the candidate pauses to think about her answer, the silence may seem deafening. Often interviewers think they have just asked a poor or unclear question so they jump in and say, "What I mean is. . ." Thus the interviewer ends up answering their own question or robbing the question of its power. Rule of thumb: don't be the next person to speak after you ask a question.
The second time to use silence effectively is after the candidate answers your question. If it is a broad and open-ended question, the candidate may provide an elaborated answer. When he finishes speaking, if you pause briefly (2-3 seconds), he may decide to share something else with you. The candidate may have been debating whether to give you any additional information. In an effort to deal with the discomfort of the silence, he might provide you with the information and insight that is more meaningful than anything else he has said.
While silence can be used to your advantage, its use is not recommended as a way of adding stress to the interview. Used correctly, silence can help you solicit important information and make valuable observations of the candidate's personality, without causing stress either to the candidate or to the interviewer.