Face to Face With Your Users: Running a Nondirected Interview
http://www.adaptivepath.com/publications/essays/archives/000081.php

Kuniavsky, Mike
Adaptive Path
2003

Abstract:

An interview is a funny situation. It's like a friendly conversation between strangers, but unlike the kind you may have on the bus. When chatting on the bus, people try very hard to agree with each other and to quickly communicate interesting information. Each person wants to be liked and adjusts the way they speak and what they say so as not to offend. This type of exchange is perfectly fine for maintaining civil society -- deeper exchanges can always happen as an acquaintance deepens -- but shallow banter isn't appropriate for an interview. You need to find out what someone is experiencing, what they're thinking, or what their real opinions are.