Identifying Altruism in the Laboratory

Recent attempts to measure altruism toward other players or charities suffer from a potential confound: the act of giving is typically correlated with the size of the pie left on the experimenter's table. Altruistic acts could thus be more generous if subjects prefer that monies go toward other players, or charities, than be left on the table. On the other hand, revealed altruism could be lower if subjects are more altruistic toward the residual claimant than they are toward the agent to whom they are being asked to give. We demonstrate this point with simple laboratory experiments that derive from popular recent designs. We find a significant effect from the hypothesized confound, with revealed altruism dependent upon who is specified as the residual claimant.