Two papers out this month together tell a simple story: we like us over them because we are biased to see our acts as more moral. The August Psychological Science says we excuse unfair choices by ourselves or our group members, but not by those from other groups:
All more confirmation my belief that morality is a big distraction.
The second finding seems related to the claims made in this article, that the things that motivate group identity are related to trust and security (rather than being "better than" other groups). Unfortunately though, the connection to ingroup bias demonstrated here appears to contradict claims in the article that ingroup identity need not be associated with conflict with or devaluation of other groups.