An article "Why Extremist Views Dominate" suggested that such views are expressed more willingly when people believe they hold a majority opinion.  In the study the point was that students that were pro-alcohol were more willing to express their opinion when they thought they were in the majority and less inclined to when faked data indicated otherwise.

One wrinkle in this study was that those students that held anti-alcohol views did not change in expressing their viewpoint even when presented with data that indicated they held a majority position.

I would dispute the conclusion that was reached in that such views are being expressed because they believe they have the support of the majority.

If that were the only viewpoint, then there wouldn't be much point in expressing the opinion.  Instead, I suspect that there is a sense that the expressed opinion is one held by the majority, but it is being "oppressed" or disapproved of by a controlling minority.  Therefore people may feel that they are speaking out and potentially even rebelling against the minority that is holding them down.

In this study, I suspect that the anti-alcohol students never felt persecuted so their perspective didn't increase their desire for expressing their views.

In fact, I would argue that this element of "disapproval" or "oppression" is precisely what has given rise to the sense of political polarization in this country.  As people tend to view, read, and engage in news programs and with people that share their perspective, there is a tendency to gain the feeling that their's is a majority position and being oppressed.

It is no coincidence that virtually every group that has an agenda, represents themselves as the underdog and is holding an opinion shared by the majority of people, but are being oppressed by some authority.  In such a discussion the majority position is presented as being quite reasonable, while those opposed are viewed as unreasonable zealots that are attempting to suppress the majority viewpoint. Discussions escalate to the point of hysteria and invariably result in an "us versus them" mentality that permeates every topic.  In effect, one is forced to take sides because there can be no reasonable discussions when each side is viewed as the enemy.

This is precisely why we can see ironic spectacles like presidential debates where the majority of candidates in one party can declare on television that they do not believe in evolution.  This type of pandering occurs because they feel comfortable expressing what they consider to be the majority opinion and therefore their statement is seen as "speaking out" against those trying to oppress them.  After all, it seems unlikely to suggest that these candidates (as an example) just recently came to this conclusion.  It is certain that it wasn't the most pressing question of the presidential debates. More importantly, why would anyone think that such an opinion even mattered, except in light of "rebelling" against those they perceive as oppressing their viewpoint.

I also want to be clear in stating that I don't believe there is any such oppression taking place, but rather it presents an excuse or a facade for people to be more militant and vocal about perceived wrongs.  As such it provides a powerful incentive for people to push agendas that might otherwise be seen as radical.