The health club where I work out has just finished a major overhaul of the locker rooms and main floor facilities. It is all tastefully and professionally done. The club earns all major accreditations from organizations that track such things.

I use the club to lift and swim, and sometimes jump on a treadmill on cold winter days when running outside would simply hurt.

The pool is just 25 meters long. It helps me build fitness with the goal of participating in Olympic distance triathlons next year.

There’s just one thing that bugs me about the club. Whenever I go to the area where the sinks are situated, Fox News is playing on the TV.

I try to ignore Fox News wherever it plays. Yet many businesses seem to like to put Fox on their TVs. One former employer had it playing on the screen where visitors sat to do business or come in for interviews.

There’s just one problem with this business philosophy. Fox News makes you dumber.

According to independent research conducted by Farleigh Dickinson University, watching Fox News actually diminishes the ability to answer questions about current events. Here’s what a story on the website RT.com revealed:

The report reveals that, on average, Americans are able to correctly answer 1.8 out of 4 questions on international news and 1.6 of 5 questions when quizzed on domestic issues. For those that disregard the television for taking in daily newscasts, they averaged 1.22 answers correctly.

Fox viewers, of course, were a different story.

“[S]omeone who watched only Fox News would be expected to answer just 1.04 domestic questions correctly – a figure which is significantly worse than if they had reported watching no media at all,” reveals the study.

“On the other hand, if they listened only to NPR, they would be expected to answer 1.51 questions correctly; viewers of Sunday morning talk shows fare similarly well. And people watching only The Daily Show with Jon Stewart could answer about 1.42 questions correctly.”

The admittedly liberal website newshound.us reveals some of the reasons behind the “Fox Effect.”

In summary, then, the “science” of Fox News clearly shows that its viewers are more misinformed than the viewers of other stations, and are indeed this way for ideological reasons. But these are not necessarily the reasons that liberals may assume. Instead, the Fox “effect” probably occurs both because the station churns out falsehoods that conservatives readily accept—falsehoods that may even seem convincing to some liberals on occasion—but also because conservatives are overwhelmingly inclined to choose to watch Fox to begin with.

At the same time, it’s important to note that they’re also disinclined to watch anything else. Fox keeps constantly in their minds the idea that the rest of the media are “biased” against them, and conservatives duly respond by saying other media aren’t worth watching—it’s just a pack of lies. According to Public Policy Polling’s annual TV News Trust Poll (the 2011 run), 72 percent of conservatives say they trust Fox News, but they also say they strongly distrust NBC, ABC, CBS and CNN. Liberals and moderates, in contrast, trust all of these outlets more than they distrust them (though they distrust Fox). This, too, suggests conservative selective exposure.

And there is an even more telling study of “Fox-only” behavior among conservatives, from Stanford’s Shanto Iyengar and Kyu Hahn of Yonsei University, in Seoul, South Korea. They conducted a classic left-right selective exposure study, giving members of different ideological groups the chance to choose stories from a news stream that provided them with a headline and a news source logo—Fox, CNN, NPR, and the BBC—but nothing else. The experiment was manipulated so that the same headline and story was randomly attributed to different news sources. The result was that Democrats and liberals were definitely less inclined to choose Fox than other sources, but spread their interest across the other outlets when it came to news. But Republicans and conservatives overwhelmingly chose Fox for hard news and even for soft news, and ignored other sources. “The probability that a Republican would select a CNN or NPR report was around 10%,” wrote the authors.

In other words Fox News is both deceiver and enabler simultaneously. First, its existence creates the opportunity for conservatives to exercise their biases, by selecting into the Fox information stream, and also by imbibing Fox-style arguments and claims that can then fuel biased reasoning about politics, science, and whatever else comes up.

This means the health club is actually doing a genuine disservice to the mental health and acuity of its members by playing Fox News on the television. And it’s not a health club… if the television is undermining the mental health and acuity of its members.

That’s all we need to say about Fox News today. It is clearly quite bad for your mental health, and bad for the health of the nation as a whole.