People are more willing to offer aid when provided with the details of a single suffering human than when confronted with the information that a large group of people is suffering identically.

Stalin epitomised the observation when he said, “A single death is a tragedy; a million deaths is a statistic.”
The economist Thomas Schelling termed this the identifiable victim effect noting that harm to a specific individual invokes “anxiety and sentiment, guilt and awe, responsibility and religion, [but]…most of this awesomeness disappears when we deal with statistical death”.

The explanations given for this human irrationality are multivariate including ex-post/ex-ante evaluation, vividness, certainty, and the innumerate nature of empathy.