Carsten Schmidt University of Mannheim, Sonderforschungsbereich 504   L13,15 Mannheim, 68131 Germany   cschmidt@sfb504.uni-mannheim.de   http://www.sfb504.uni-mannheim.de/~cschmidt           JEL Areas: C9 : Design of Experiments: General C7 : Game Theory and Bargaining Theory:General