Elicitation: "Acquisition of information from a person or group in a manner that does not disclose the intent of the interview or conversation. A technique of human source intelligence collection, generally overt, unless the collector is other than he or she purports to be."You don't hear much about elicitation. An element of intel operations tradecraft, many consider it the seedier side of HUMINT (or, as the business guys call it, "primary source") intelligence in the corporate world.
The best introduction to this world, in my opinion, is John Nolan's excellent book Confidential (which you can now buy in paperback).
Another useful product came across my desk the other day, however. One of my students (Thanks, Nimalan!) forwarded the very interesting slide presentation at the bottom of this post by Stephan Hernan who appears to be an independent analyst working health, science, and communications technology issues.
Whether you are curious about elicitation generally or are more interested in the counterintel implications of these techniques, I recommend the slide show: