What is 'identifiable victim effect' in philanthropy?

This refers to people’s tendency to donate more money and gifts when they are told about the sufferings of an individual rather than when they are told about the problems of a large group. So, a person may be more likely to donate for a development cause when he is persuaded with information about a poor man's abject living conditions instead of the miseries of the world’s poor. The identifiable victim effect is seen as preventing donors from making objective decisions. Instead, it makes them take emotional decisions that may not necessarily help out the most unfortunate victims in need of help.