Income effect and altruism

We investigate the consequences of a pure income effect on the altruistic behavior of donors. Inequity aversion theories predict either no effect or a decrease in giving, whereas warm-glow theory predicts an increase in giving with an increase in the common income of donor and receiver. Theoretical predictions being contradictory, we run a dictator game in which we vary the common show-up fee of both the dictator and the recipient, but keep an extra amount to be shared the same. The prediction of the warm-glow theory is supported.