Clash of the Temperaments: Why Vendettas Perpetuate

The Vendetta Game dynamically models conflict resolution processes in which players can take turns to steal from one another probabilities of winning a prize. Vendettas are far more prevalent in the laboratory than predicted in equilibrium, assuming self-interest or even spite. To make sense of this, we identify four behavioral types each with their temperaments: melancholic Gamesmen (27%) who play equilibrium, antisocially sanguine Sharks (53%) who optimistically demand more than their equilibrium share, choleric Educators (17%) who punish greedy co-players or otherwise play equilibrium, and phlegmatic Meeks (3%) who demand less than their equilibrium share. Within games, i.e. through the course of stealing and counter-stealing, non-Sharks become greedier. Across games, the characteristic profiles of subject types sharpen with experience. Sharks earn least and Meeks earn most. The clash of temperaments perpetuates feuds. We compare our four types with the types of players observed in the related Repeated Prisoner s Dilemma game.