EVOLUTION AND ULTIMATUM BARGAINING

Empirical research has discovered that experimental subjects in ultima tum bargaining situations generally fail to play the decision-theoreti c optimum strategy, and instead play something between that strategy a nd a fair split. In evolutionary dynamics, fair division and nearly fa ir division strategies often go to fixation and weakly dominated strat egies can do quite well. Computer simulations were done using three di fferent ultimatum bargaining games as determinates of fitness. (1) No tendency toward the elimination of weakly dominated strategies was obs erved, with or without mutation. (2) Strategies making fair demands ha d sizable basins of attraction. (3) In a system where five different d emands can be made, demands closest to (approximately) 91% had the lar gest basins of attraction. (4) If the strategies have thresholds for a cceptable demands, rather than individuated responses to each demand, the apparent optimum demand may be quite low: 64% for one set of trial s.