Income inequality may foster greater self-enhancement through increased competition. Takata (2003) found that when Japanese participants were asked to compete over a limited resource under zero-sum conditions (i.e., the winner receives everything, the loser nothing), they displayed levels of self-enhancement similar to the levels displayed by Americans. That is, when people compete over concentrated rewards, they have a tendency to self-enhance ...

In societies with more income equality, people may not only have more equal incomes, but they may also feel a pressure to seem more similar to others. This may manifest as a modesty norm, whereby people are discouraged from voicing both real and perceived superiority

Despite stereotypes, America is actually in the middle of pack when it comes to self-enhancement. But it’s ahead of most industrialized nations, which could still make it the land of Garrison Keillor’s Lake Wobegon — “where all the women are strong, all the men are good looking, and all the children are above average.”