‘Psychic numbing‘ is a relatively new term, assigned to the phenomenon which shows people tend to feel less urgent compassion, and tend to give less, when the suffering in question is shown to be more systemic and more pervasive, or affecting larger numbers of people. Some psychologists believe it is linked to our intuitive sense that if one suffers alone, the suffering is worse, but if one is accompanied, there might be some security in numbers, not just emotionally, but practically.
The individual does not actually suffer less, but somehow, human beings —across cultures, ages groups and regions— appear to have an almost inborn tendency to convince themselves that the one who suffers with others is somehow safer. This is, of course, rarely true. While yes, a young boy might survive because his older sister goes without food, two young children in a population beset with pervasive, persistent scarcity or political disorder, may be at significantly heightened risk of violence, or even enslavement.