I wonder if this is because we can identify with an individual but a group is seen as separate from ourselves. Also, could it be because one person helping another feels much less overwhelming than one person trying to help a group of people? What would happen if they grouped the participants first then saw how many they would hope to help?
Probably because we feel that we CAN ACTUALLY same one persons life, but when faced with a group of people, we feel there's nothing we can actually do. Makes sense to me anyway. None of this surprises me, and I'm amazed academics waste time doing such studies. Isn't this pretty damned obvious?
Its a natural defence mechanism. You cant deal with the problems of everyone around you ... You need to deal with your **** first. With people who you can clearly identify with, you may see it as part of your own problem. But as soon as that number increases, they are just a group separate to your own. Like a separate social group (e.g. another tribe) whose problems are not your own.
As the others have said, I would tend to agree that it is easier to identify and empathise with an individual rather than a group. We see so much trouble in the world that it can become overwhelming, we think what difference can I make an individual. When dealing with the troubles of a single person we may be more able to envisage making a difference.
However, the opposite is true and it's equally wrong in my eyes. A mini-disaster occurs, a local flood or fire, a stadium collapse, maybe killing a dozen or so, makes the headlines and someone starts a national collection that raises umpteen thousand to help the survivors and victims' families. The Bradford stadium fire killed 56, injured 265, "sent shockwaves round the world, with messages of sympathy arriving from the Queen, the Pope, the Prime Minister, Church leaders and a host of political figures from around the globe", the Disaster Fund raised £3.35M. Some individual gets killed driving home leaving a wife and kids and he's lucky if it makes the local paper. We like our tragedies to be bite-size one-off events, not ongoing things like starvation and road accidents.
Joseph Stalin. "One death is a tragedy, a million is a statistic". I remember reading that off a Call of Duty loading screen.
We'd be overloaded by emotions if we all cared about everyone else the same way as what we care about our family and friends. Imagine how productive that would be...
& who says video games aren't educational? (I've learned a lot of history & geography from war games)
Unfortunately it seems to be human nature. People can't feel compassion about what they can't comprehend - after all, unless you have seen it with your own eyes, can you really comprehend a whole village being wiped out?