From many experiments, it is known that economists are more selfish than others. the interesting question is whether selfish people select themselves into Economics, or whether Economics students get indoctrinated by the material they are covering in classes.
Yoram Bauman and Elaina Rose use data from students at the University of Washington to elucidate this. There, students can donate to social programs each quarter. This is tracked along with their taking Economics classes. While Economics majors are indeed less generous, this does not appear to evolve over time. One can thus conclude this is a section effect. However, non-majors become more selfish once exposed to Economics. In other words, economists are quite convincing.