A practice which has an XP team asking itself, at the end of each iteration :
Note: In practice, this must be presented in an extremely visible way. Simply sending around an e-mail asking these questions is not enough. Goofing off or doing work is seen as more important, and there's always more work or goofing off to do. So, this needs to be obviously a high-priority task.
Any suggestions on how to encourage feedback on this? -- Brent P. Newhall
I recommend that you use techniques from ProjectRetrospectives.
At the end of the iteration, get the team together for a hour and looking back on the previous iteration build a time-line, NormKerth has an exercise in his book called Emotional Seismograph that you can use.
Once you have a time-line try to determine (scribe these on a flip-chart or white-board as you go):