In yesterday’s Washington Post Shankar Vedantam had another fascinating bias article, "Disagree About Iraq? You’re Not Just Wrong — You’re Evil."

What is interesting about the [Iraq war] clash from a psychological perspective is not that supporters and critics disagree, but that large numbers of people on both sides claim to know the motives of people who disagree with them. … A wide body of psychological research shows that on any number of hot-button issues, people seem hard-wired to believe the worst about those who disagree with them. … said Glenn D. Reeder, a social psychologist at Illinois State University … "We find it difficult to grant that other people come to their conclusions in good faith if they reach a conclusion that is different than ours." …

When Reeder and his colleagues asked pro-war and antiwar Americans how they would describe the other side’s motives, the researchers found that the groups suffered from an identical bias: People described others who agreed with them as motivated by ethics and principle, but felt that the people who disagreed with them were motivated by narrow self-interest. …

Studies have found, for example, that people believe that those who disagree with them are less informed and that those who agree with them are better informed. On issues in which information is widely available, people concede that their opponents are knowledgeable but insist that their conclusions are self-serving and biased.  Another study found that liberals and conservatives not only overestimate their opponents’ partisan motives on questions such as abortion and same-sex marriage but also overestimate the partisan motives of people on their own side.

The article neglected to mention that in addition to over-estimating self-serving biases in others, we probably also underestimate them in ourselves.  I suspect this was not a random oversight.