David Weinberger wrote an article for Salon rebutting the argument that online spaces and communities create an echo chamber effect:
This meme turns out to be as tricky as it is attractive. Worse, as it spreads itself, it’s shifting shape, so that the entire Internet can start to seem to be nothing but a set of sealed rooms, each constructing – and then confirming – reality out of nothing but proclamations of prejudice and wishes. In echo chambers, the argument has it, the sound of our own voices can drown out fast-changing reality, as supposedly happened to the Dean campaign’s online legions.
Danah continues the discussion
In social networks literature, there’s a concept called homophily. The basic idea is that birds of a feather stick together. The more we have in common with someone, the more points of context, the more capable they are of supporting us. We are more likely to gain social and emotional support from people who are awefully similar to us. Our strong ties are usually very similar to us.