Groupthink is a very well-documented source of bias in cognitive psychology. It refers to the tendency of humans to tend to agree with each other, and hold back objections or dissent even when the group is clearly moving in a very wrong direction.
There seems to be a balance of tensions between evaporative cooling of beliefs leading to groupthink, and extremely biased color politics. This is an underexplored issue.
An echo chamber is a group of media sources that parrot each other by constantly and unquestioningly reporting a single, biased point of view, thus creating the illusion of consensus....