  First, Daniel Batson and colleagues found that increased empathy leads to increased helping behaviour.  One hypothesis is altruistic: empathy causes a non-instrumental desire to help.  There are many competing egoistic hypotheses.  Empathy might cause an unpleasant experience that subjects believe they can stop by helping; or subjects might think failing to help in cases of high empathy is more likely to lead to punishment by others, or that helping here is more likely to be rewarded by others; or subjects might think this about self-administered punishment or reward.  In an ingenious series of experiments, Batson compared the egoistic hypotheses, one by one, against the altruistic hypothesis.  He found that the altruistic hypothesis always made superior predictions.  Against the unpleasant experience hypothesis, Batson found that giving high-empathy subjects easy ways of stopping the experience other than by helping did not reduce helping.  Against the punishment by others hypothesis, Batson found that letting high-empathy subjects believe that their behaviour would be secret did not reduce helping.  Against the self-administered reward hypothesis, Batson found that the mood of high-empathy subjects depended on whether they believed that help was needed, whether or not they could do the helping, rather than on whether they helped (and so could self-reward).  Against the self-administered punishment hypothesis, Batson found that making high-empathy subjects believe they would feel less guilt from not helping (by letting them believe that few others had volunteered to help) did not reduce helping.