In addition to different negotiation styles and negotiating techniques  there are a number of different things that negotiators need to be able  to deal with during a negotiation. 

Being overconfident is one of these. What we need to understand is that if we allow ourselves to become overconfident, then there is a good chance that it is going to affect both our judgement and our decision making process. 

What we need are ways to detect when we are becoming overconfident and ways to deal with it when it happens.