Watching Fox News can be like entering an alternative universe. It’s a world where Vladimir Putin isn’t actually that bad, but vaccines may be, and where some unhinged rightwing figures are celebrated as heroes, but Anthony Fauci, America’s top public health official, is an unrivaled villain.

Given the steady stream of misinformation an avid Fox News consumer is subjected to, the viewers – predominantly elderly, white and Donald Trump-supporting – are sometimes written off as lost causes by Democrats and progressives, but according to a new study, there is still hope.

In an unusual, and labor intensive, project, two political scientists paid a group of regular Fox News viewers to instead watch CNN for a month. At the end of the period, the researchers found surprising results; some of the Fox News watchers had changed their minds on a range of key issues, including the US response to coronavirus and Democrats’ attitude to police.

The findings suggest that political perspectives can be changed – but also reveals the influence partisan media has on viewers’ ideology.

Polls have previously shown that viewers of Fox News, the most-watched cable news channel in the US, are far more likely to believe the false claim that the 2020 presidential election was stolen than the average American, and are more likely to believe falsehoods about Covid-19.

The extent of the network’s influence on American politics was highlighted this week, with a report that Joe Biden has privately referred to Rupert Murdoch, the owner of Fox News, as “the most dangerous man in the world” and “one of the most destructive forces in the United States”.

David Broockman and Joshua Kalla, political scientists at the University of California, Berkeley and Yale university, respectively, paid 304 regular Fox News viewers $15 an hour to instead watch up to seven hours of CNN a week during the month of September 2020. The switchers were given regular news quizzes to make sure they were indeed watching CNN, while a control group of Fox News viewers continued with their regular media diet.

Much of the news cycle in September 2020 focused on policing and protests in Kenosha, Wisconsin, which began after Jacob Blake, a Black man, was shot and seriously injured by police in late August. During the protests Kyle Rittenhouse, a teenager from Illinois, shot and killed two men and wounded another. The events became a political tool for Republicans, including Donald Trump, who later announced he would send federal law enforcement agents to Kenosha.

By the end of September, the CNN watchers were less likely to agree that: “It is an overreaction to go out and protest in response to the police shooting of Jacob Blake in Kenosha, Wisconsin” and less likely to believe that: “If Joe Biden is elected President, we’ll see many police get shot by Black Lives Matter activists”, when compared with their peers who continued watching Fox News.

The CNN switchers were also, as Bloomberg’s Matthew Yglesias reported, 10 points less likely to believe that Joe Biden supporters were happy when police officers get shot, and 11 points less likely to believe that it is “more important for the President to focus on violent protests than the coronavirus pandemic”.

In addition the CNN viewers were 13 points less likely than the Fox News viewers to agree that: “If Joe Biden is elected President, we’ll see many more police get shot by Black Lives Matter activists.”

In an email interview, Kalla said he and Broockman had not necessarily expected people’s opinions to change.

“I think the most surprising finding is that shifting people’s media diets from Fox News to CNN for a month had any effect,” Kalla said. “People who watch cable news tend to be very politically engaged and have strong opinions about politics, limiting the impact of the media. Similarly, they also tend to be strong partisans who might not trust any source not associated with their party.”

The people in the experiment, Kalla said, were “overwhelmingly pro-Trump Republicans”. Given Trump had spent much of his presidency bashing CNN – a regular chant at his rallies was “CNN sucks!” – the results are particularly surprising.

“A lot of people might expect this audience to completely resist what CNN had to say, but we see people learning what CNN was reporting and changing their attitudes, too. It is therefore surprising that watching CNN had any impact at all in this experiment,” Kalla said.

Fox News, and liberal networks, can influence their viewers through “agenda-setting” – covering a certain topic relentlessly – and “framing”, Kalla said – by emphasizing certain aspects of an issue.

Kalla and Broockman were particularly interested in a third method of influencing: “partisan coverage filtering” – which they defined in the study as the process where “partisan outlets selectively report information, leading viewers to learn a biased set of facts”.

They gave a hypothetical example of how news channels might cover a war. In the example, CNN might cover the cost of the war and the number of military personnel and civilians who died. Fox News, on the other hand, could focus on the severity of the threat that Trump’s military campaign had countered, and feature stories of liberated civilians welcoming American soldiers.

“This leaves viewers of each network with different factual understandings of the conflict, and subsequently different levels of support for the conflict and the president,” Broockman and Kalla wrote.

Most of the CNN switchers stuck to the length of the task, according to the study. But once it was over, and the $15 an hour was taken away, “viewers returned to watching Fox News”, Kalla said.

While the study proved that people are susceptible – at least under the right conditions – to different political opinions, in the longer-term the skewing of media has had a broader, and negative, impact on the way the US functions, Kalla said.

“When politicians do something bad, we hope that voters will punish them, irregardless of their party – otherwise, politicians won’t have to work hard to make our lives better in order to keep their jobs,” Kalla said.

“However, this type of behavior becomes less possible if the media engages in partisan coverage filtering. If CNN doesn’t cover bad things Democrats do or good things Republicans do, and if Fox News doesn’t cover bad things Republicans do or good things Democrats do, then voters become less likely to learn this information and less able to hold their elected officials accountable.

“This is troubling for the functioning of a healthy democracy.”