A few days ago, driving through South Carolina, I saw a billboard advertising a radio station that's part of the "Excellence in Broadcasting" network.

So, always seeking excellence, I tuned the dial to the station and found myself listening to Rush Limbaugh. "Excellence in Broadcasting" is a term Limbaugh modestly invented for his own show.

For those of you who have never heard Limbaugh, he's an iconic entertainer who addresses his huge audience through a bullhorn from the far right end of the Republican Party.

That day, he was angry at the "Republican establishment media" for attacks on Newt Gingrich, who Limbaugh evidently feels is the only Republican in the nomination race able to beat Barack Obama.

I had to think about that one. I hadn't realized there was a left-right spectrum within the conservative media, but it makes sense. It also helps explain the quirky rise of someone like Gingrich to the top of the Republican food chain.

'Selective exposure'

This country's political discourse is angry and discordant, like a malfunctioning television left on at full volume.

There's a left-right spectrum within the conservative media, and it helps explain the quirky rise of someone like Newt Gingrich to the top of the Republican food chain. (Nathan Gray, The Independent-Mail/Associated Press)

It's soaked with religion and race, and it obsesses over trivialities — are Muslims bringing Shariah law to America? — while ignoring matters of real importance. (I have yet to hear any serious public discussion of the unravelling euro, and whether that contagion will spread to America.)

To properly understand this place, I think, you have to listen to all the participants in the echo chamber: the screamers on the left, the howlers on the right and everything in between.

Evidently, though, Americans increasingly believe the opposite.

According to a study by professors at Stanford University and UCLA, more and more people here are cocooning themselves in media they know will cater to their particular biases.

The professors call it "selective exposure."

Liberals apparently tend to stick with left-leaning MSNBC, websites like Huffington Post and the Daily Kos, National Public Radio (which I actually find more priggishly balanced than any other news outlet), and CNN.

The big draw for Conservatives is Fox News Channel and Limbaugh. They also gravitate to newsmax.com, the Washington Times, Glenn Beck’s new channel, and of course the galaxy of right-wing shows on talk radio, a medium conservatives seem to own.

The result, of course, is a political discourse in which progressives and conservatives increasingly just yell at each other, having long ago ceased listening.

Blame the messenger

The phenomenon also has another consequence: blaming the messenger.

Just as liberals I know seem to loathe people like Limbaugh, I've often heard conservatives tell me through clenched teeth that I'm clearly part of a mainstream media plot to destroy their leaders.

(Progressives see the same sort of dark forces operating against them. Remember Hillary Clinton's "vast right-wing conspiracy" during her campaigning days.)

Gingrich cannily tapped into this media-hatred lode when he was asked during the candidates' debate Thursday night about allegations, by one of his ex-wives, that he had wanted to legitimize his philandering by getting her to agree to an "open marriage."

Given that Gingrich was, and remains, a warrior for "family values," and given that the whole country was talking about the interview, and given how negative and nasty all the candidates' campaigns have become, it seemed a fair question.

But Gingrich turned it into an attack on the left-leaning "elite" media, who, he said, were working together to ensure Obama’s election.

His ex-wife's remarks on ABC News, he said, were all just part of that campaign, and he was "appalled."

Life in the cocoon

The audience, mostly Christian conservatives, went nuts. Gingrich was finally shining a national spotlight on one of their most treasured Limbaugh-esque theories.

Pundits immediately predicted, correctly it turned out, that it would help push him over the top in South Carolina on Saturday.

The wildly cheering crowd was happy to overlook Gingrich's affairs, and clearly didn’t give a fig about his colossal hypocrisy.

This is, after all, a man who, while vigorously pursuing another woman, led the effort to impeach Bill Clinton after it was discovered Clinton had been having an affair with a White House intern.

(Incidentally, I don't recall Gingrich or any other conservatives ever scolding the so-called elite media for going after the lurid details of Clinton's infidelities.)

But it has long since reached the point in this country where facts have ceased to matter.

Only in America, I think, is it possible to run against the media, and the California study offers one good reason why: Americans voluntarily living in an endless feedback loop designed to prop up their own conceptions and misconceptions.

Constant jibes

Consider some of the reasons why many conservatives despise Obama: He has no moral compass, they say. Well, this is a family man in a long-term, apparently stable marriage that has not a whiff of scandal. In that respect, Obama more closely resembles George W. Bush than Gingrich, who now talks of seeking God's forgiveness for his extramarital adventures.

Another trope: Obama constantly apologizes for America abroad. There is no record of Obama ever having done so, unless you're truly paranoid about his early olive branch to the Islamic world, or furious about his reflection that while he believes America is "exceptional," most other countries regard themselves the same way.

Then there are the constant jibes that he's a socialist (despite having consistently coddled Wall Street with bailout money and tax cuts) and soft on terrorists (tell that to Osama bin Laden or the hundreds killed by this administration’s steeply accelerated program of drone strikes abroad).

Likewise, anyone who spends his or her time entirely inside the MSNBC or Daily Kos universe probably believes Mitt Romney is a parasitic corporate predator, Ron Paul is a libertarian nut case and Rick Santorum wants to turn America into an Iran-like theocracy. Gingrich is written off as a bloviating narcissist.

It’s all foolishness of course. All four of the remaining Republican candidates say worthwhile things, as does Obama.

But listening to the other side makes thinking more complicated, and can upset one's life inside the cocoon.

It's much easier to self-reinforce, and bare your teeth. But it is unserious, and no way to pick a leader.