Much or more? Experiments of rationality and spite with school children

In a competitive environment the maximization of self-interest and theminimization of the other's interest can be seen as the two faces of thesame coin. However, these motivations can lead to very differentbehaviors. In order to understand how these are expressed, we designedan experiment to measure the ability of children and teenagers to react tostimuli that induce behavior to act as a rational player (maximization ofself interest) or as a spiteful player (minimization of other's interest).Each player faced the following dilemma: maximizing pay-off andincurring the risk of having a lower pay-off; or alternatively guaranteeingone's own pay-off was not smaller than the opponent's pay-off. A prizewas attributed proportionally to the pay-off (Treatment 1) or to the playerwith highest pay-off (Treatment 2), which meant that the optimalbehavior was different for each treatment. We performed experimentswith 398 Portuguese children and teenagers and found evidence thatyounger children tended to be maximizers (in both variants) and thatteenagers tended towards rational behavior when it was best for them andtowards spiteful behavior when the latter was more advantageous.