Comments can be bad for science. That's why, here at PopularScience.com, we're shutting them off.

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...even a fractious minority wields enough power to skew a reader's perception of a story, recent research suggests. In one study led by University of Wisconsin-Madison professor Dominique Brossard, 1,183 Americans read a fake blog post on nanotechnology and revealed in survey questions how they felt about the subject (are they wary of the benefits or supportive?). Then, through a randomly assigned condition, they read either epithet- and insult-laden comments ("If you don't see the benefits of using nanotechnology in these kinds of products, you're an idiot" ) or civil comments. The results, as Brossard and coauthor Dietram A. Scheufele wrote in a New York Times op-ed:

Uncivil comments not only polarized readers, but they often changed a participant's interpretation of the news story itself.

In the civil group, those who initially did or did not support the technology — whom we identified with preliminary survey questions — continued to feel the same way after reading the comments. Those exposed to rude comments, however, ended up with a much more polarized understanding of the risks connected with the technology.

Simply including an ad hominem attack in a reader comment was enough to make study participants think the downside of the reported technology was greater than they'd previously thought.

Another, similarly designed study found that just firmly worded (but not uncivil) disagreements between commenters impacted readers' perception of science.

If you carry out those results to their logical end--commenters shape public opinion; public opinion shapes public policy; public policy shapes how and whether and what research gets funded--you start to see why we feel compelled to hit the "off" switch.

Comments on articles erode the public's trust in science.

In July, NPR.org recorded nearly 33 million unique users, and 491,000 comments. But those comments came from just 19,400 commenters, Montgomery said. That's 0.06 percent of users who are commenting, a number that has stayed steady through 2016.

When NPR analyzed the number of people who left at least one comment in both June and July, the numbers showed an even more interesting pattern: Just 4,300 users posted about 145 comments apiece, or 67 percent of all NPR.org comments for the two months. More than half of all comments in May, June and July combined came from a mere 2,600 users. The conclusion: NPR's commenting system — which gets more expensive the more comments that are posted, and in some months has cost NPR twice what was budgeted — is serving a very, very small slice of its overall audience.