National outbreaks of fake news and partisan “disinformation” have convinced many Americans to doubt scientific consensus—such as the near-unanimous agreement among experts that human-caused climate change is real and a global threat and that vaccines are safe, effective, and life-saving.

While respectable media outlets are scrambling to fact-check and refute such “merchants of doubt,” a group of researchers, led by a psychologist at Cambridge, think they can stamp out the viral spread of fake news and lies just like we stamp out every other infectious disease—with vaccinations.

Their ‘mental inoculation’ works under the same principal as actual innoculations—that is, exposure to a weakened version or fragment of some nasty contagion can allow a person to recognize and develop immunity to future threats. In their study, the researchers found that they could effectively ‘vaccinate’ Americans from climate change misinformation by presenting them with information on the scientific consensus alongside a pre-emptive caution that some politically motivated groups are spreading lies about that consensus.

The inoculation method, published Monday in the journal Global Challenges, was effective regardless of participants’ political leanings; Republicans, Democrats, and Independents were equally likely to reject the misinformation when it was subsequently presented to them. And among those predisposed to believe climate misinformation, the researchers saw no evidence that the inoculation could backfire, making them more resistant to scientific facts.

The study didn’t look at how long the protection lasted—if “booster shots” might be needed—or all of the real-world scenarios in which people might be exposed to fake news. However, the researchers are hopeful that the tactic could help de-polarize issues and steer public conversations back to scientific data and evidence-based policies.

“There will always be people completely resistant to change, but we tend to find there is room for most people to change their minds, even just a little,” said Sander van der Linden, a social psychologist from the University of Cambridge and director of the Cambridge Social Decision-Making Lab.

For the study, van der Linden and his colleagues first did an experiment to figure out the most persuasive and common myth about climate science. Surveying a nationally representative group of 1,000 volunteers, the researchers landed on this statement: “there is no consensus on human-caused climate change.”

This myth was based on a real-world “disinformation campaign” in 2007 called the “The Oregon Global Warming Petition Project.” In that campaign, politically motivated actors claimed that more than 31,000 American scientists had signed a petition saying that there is no scientific evidence that human-created carbon dioxide emissions will cause catastrophic heating of the Earth’s atmosphere.

Next, the researchers recruited a diverse group of 2,167 volunteers from Amazon Mechanical Turk. The researchers disguised the purpose of the study, telling each volunteer that they would randomly be asked about 1 of 20 possible media topics. But every participant was asked about climate change, starting with their initial thoughts on the matter so that the researchers could gauge opinion shifts for each participant individually.

A shot of facts

For a group of just 338 participants, the researchers showed them just a pie graph indicating that “97 percent of climate scientists have concluded that human-caused climate change is happening”—which is true. Afterward, that group reported an average 20 percentage-point jump in their perception that there was a scientific consensus on climate change.

Another 392 participants, on the other hand, were shown just a screenshot of the Oregon disinformation campaign. That group saw a nine percentage-point drop in their belief in a scientific consensus.

A third group of 352 participants saw both, the accurate pie chart followed by the disinformation screenshot. The two pieces of information “neutralized” each other, the researchers found. This resulted in no real change in their initial thoughts on a scientific consensus.

These findings largely backed up what researchers already knew: accurate information about the consensus has positive effects on people’s perception. But misinformation can have negative effects and wipe out positive effects.

Next, the researchers tested two “vaccination” groups. A group of 363 participants saw the pie graph alongside a “general inoculation,” that is a brief explanation about the disinformation campaign (the picture above). The second group of 362 participants saw the pie chart alongside more detailed information about the disinformation campaign (the picture to the right).

This detailed information mentioned that 31,000 would only represent 0.3 percent of all scientists, a tiny fraction. Moreover, many of the petition’s signature were fake, including Charles Darwin, members of the Spice Girls, and characters from Star Wars. And finally:

"...nearly all of the legitimate signers have no expertise in climate science at all. In fact, less than 1 percent of those who signed the petition claim to have any background in Climate or Atmospheric Science. Simply calling yourself a “scientist” does not make someone an expert in climate science. By contrast, 97 percent of actual climate scientists agree that human-caused climate change is happening."

Next, both vaccination groups were shown the screenshot of the disinformation campaign—and it didn’t neutralize the accurate pie chart information. Those that got a general inoculation saw a 6.5 percentage-point increase in their belief of a scientific consensus. Those that got the more detailed inoculation saw a 13 percentage-point jump.

(The remaining 360 participants acted as a control and only saw a word puzzle.)

In all, the researchers concluded that “pre-emptively warning people about politically motivated attempts to spread misinformation helps promote and protect (“inoculate”) public attitudes about the scientific consensus.”

Global Challenges, 2017. DOI: 10.1002/gch2.201600008 (About DOIs).