Psychologists who study giving behavior ① have noticed that some people give substantial amounts to one or two charities, while others give small amounts to many charities. Those who donate to one or two charities seek evidence about what the charity is doing and ② what it is really having a positive impact. If the evidence indicates that the charity is really helping others, they make a substantial donation. Those who give small amounts to many charities are not so interested in whether what they are ③ doing helps others ─ psychologists call them warm glow givers. Knowing that they are giving makes ④ them feel good, regardless of the impact of their donation. In many cases the donation is so small ─ $10 or less ─ that if they stopped ⑤ to think, they would realize that the cost of processing the donation is likely to exceed any benefit it brings to the charity.