When trying to understand political gridlock in Washington, it is helpful to consider what legal scholar Cass Sunstein wrote on Sept. 17:
IT is well known that when like-minded people get together, they tend to end up thinking a more extreme version of what they thought before they started to talk. The same kind of echo-chamber effect can happen as people get news from various media. Liberals viewing MSNBC or reading left-of-center blogs may well end up embracing liberal talking points even more firmly; conservative fans of Fox News may well react in similar fashion on the right.
The result can be a situation in which beliefs do not merely harden but migrate toward the extreme ends of the political spectrum.
You might expect that people’s views would soften and that divisions between groups would get smaller. That is not what usually happens. On the contrary, people’s original beliefs tend to harden and the original divisions typically get bigger. Balanced presentations can fuel unbalanced views.
What explains this? The answer is called “biased assimilation,” which means that people assimilate new information in a selective fashion. When people get information that supports what they initially thought, they give it considerable weight. When they get information that undermines their initial beliefs, they tend to dismiss it.