Before you can start negotiating, you have to “contain” the situation.
In everyday negotiations, this means you have to know what you’re negotiating about. You must know your goal before you can achieve it.
“Breaking containment”—switching the negotiating subject—is sometimes a deliberate strategy. When the other side employs it, recognize that you have moved back to the prenegotiating phase.
Closing the deal can be dangerous for the negotiating team. They become emotionally attached to making a deal once they’ve hit that stage.