In the military this was called 'incestuous amplification', I don't know what the civilian term for it is. We tend to lend more credence and legitimacy to that portion of a population that agrees with our own views.<p>Be very careful about falling prey to it. It has actually cost the US military dearly over the past 8 or 9 years. There are actually far reaching initiatives being pursued, at all levels of the military, to mitigate its effect with respect to groupthink in the future.