Edit: This should properly be titled “Dispersion and Implosion in Teams.” See Tobias’ comment.
Exercise at ScrumGathering 2010: how simple internal models (“rules”) can have very different effects on team behavior.
In the first situation, each person has to use their “best friend” to protect themselves from their own “worst enemy.” (In this case, you “protect” yourself by moving so that your “friend” is between you and your “enemy.”)
Notice how the group fragments and disperses.
In the second situation, there’s one little change: each person has to protect their “friend” from their “enemy.”
Bit of a difference! The overall behavior is toward cohesion.
P.S. “Kids, don’t try this at home!” This exercise works because the participants agree to the rules. It does NOT imply that you can simply give people rules to follow and expect to get the desired behavior. Why not? Because people aren’t machines, that’s why not! :) The art of the team is, of course, in coaching and coaxing the teams such that the individuals experience a shift in their own “internal rules.”