Matt Murteen blogs Dave Snowden at the Gurteen Knowledge conference talking about why knowledge can'tbe distilled from interviewing people about what they know:

Human knowledge is stored in patterns far more than raw skills and artifacts. Knowledge is in the fingertips and needs to managed in a different way. This is both our power & our downfall. It also means that you can't get knowledge from people by interviewing them because:

• I only know what I know when I need to know it
• The way we know things is not the way we think we do things
• "I know more than I can say. I will always say more than I can write down.
• Knowledge can only be volunteer[ed] it can't be conscripted

This last is very important because it means that incentives and other attempts to make people share produce the wrong behaviour. People will either camouflage, or dissemble.

He also talks about something he calls a third generation approach to knowledge management that separates knowledge into:

Content: Very high cost associated with proper codifications. Only where it's needed and we have stablity of knowledge. Knowledge goes out of date before you complete the documentation process. (A big problem in government).

Narrative: What I can speak but not write down.

Context: What I can neither "say down", nor write down. Context is the basis for the success of apprentice schemes and the reason they are being re-introduced (e.g. Cynefin's IBM Inside programme). The most effective way of doing complex knowledge transfer. You only qualify once the master agrees you've got it, exams are not enough

...via elearningpost