Both Slate and the Washington Post have interesting new article summarizing recent social science research showing that voters tend to be highly biased in their evaluation of political information. Voters tend to overvalue the importance of new information that supports their preexisting views or makes their preferred party look good; and they tend to discount any information that cuts the other way. As the Slate article puts it:
This has nothing to do with ideology. Politics isn’t about ideology. It’s about joining a team, and we judge fairness as partisans. In 1951, Princeton and Dartmouth students watched a film of a football game and were asked to take note of foul play. Princeton stalwarts saw all the penalties that should have been called on the Dartmouth players. Dartmouth students were convinced the refs missed clips and offsides committed by the Princeton players.
We judge politics the same way