Three groups of subjects were asked how much they would pay to save 2,000 / 20,000 / 200,000 migrating birds from drowning in uncovered oil ponds. The groups respectively answered $80, $78, and $88.1
The usual finding is that exponential increases in scope create linear increases in willingness-to-pay—perhaps corresponding to the linear time for our eyes to glaze over the zeroes; this small amount of affect is added, not multiplied, with the prototype affect. An alternative hypothesis is “purchase of moral satisfaction.” People spend enough money to create a warm glow in themselves, a sense of having done their duty. The level of spending needed to purchase a warm glow depends on personality and financial situation, but it certainly has nothing to do with the number of birds.
(or extension neglect) We can concretely imagine only up till maybe five. Than it's start quickly fading. We cannot really imagine numbers larger than 15. The larger the number the larger scope neglect will be. It extend also on so called extension neglect. We cannot comprehend big chunks of time, of amount of people, of how much some specific thing relates to the larger whole etc.
Example: in a document Shoa, a Nazi director of a concentration camp, when asked how many people were in killed in his camp, answered: "40,000 or 400,000"
50,000 Orbeez (1 pack)
100 mln Orbeez
Do you think your mind would capture the difference between 400k and 100mln correctly?