Many weeks during mediation, it appears that not a day will go by without having some overt demonstration of anger being shown by one of the participants during the mediation. The question, however, is whether the anger has an effect on the negotiations. Anecdotally, it cannot not have an effect. The only issue is whether it can help to increase or decrease your negotiating position.
One study recently addressed this issue from a cultural perspective. Researchers Hajo Adam and Aiwa Shirako evaluated whether culture affected how anger was percieved. The research found that in a hypothetical negotiation scenario (Study 1) and a computer-mediated negotiation simulation (Study 2), expressing anger (relative to not expressing anger) obtained larger concessions from European/American negotiators, but smaller concessions from Asian and Asian American negotiators. In both of the two studies, the anger was not appropriate to the circumstance. However, when the anger was appropriate to the circumstances, Asian and Asian American negotiators made larger concessions to the angry opponent, and their concessions were as large as was typical for European American negotiators. Across the board, the study found that anger elicited greater concessions from the Europeans and Americans. This was in part based on the fact that expressions of anger are more accepted in the European and American culture. The study also showed that expressions of anger can be very detrimental in negotiations with Asians.
The reality is that anger is a a very dangerous thing and the use of it can backfire more than it can create concessions. Often, even in cultures that accept anger, it can lead to parties shutting down because of their emotional response to the anger. This study proves that emotional reactions to the use of anger can have very real consequences to negotiations.
In my experience, the study may have it wrong as to the reasons for the concessions. For example, with Euro/American participants, they are shocked by the use of anger. They generally have one of two responses: They shut down or they make greater concessions. This could be because many Northern European cultures are not emotionally expressive cultures (as opposed to countries in Latin America or in the Middle East). The Asian culture is also even more restrictive of emotional outbursts of anger.
There could also be a different effect when there is mediation versus direct negotiations. Often the parties are more willing to express their anger to the third party mediator knowing that the full expression of that anger won’t be communicated to the other side.
It would be interesting to see the use of anger with such emotionally expressive cultures and also to see how such anger worked in the context of a mediated case.