Cable news networks have become more polarized in the last decade, study says

With Americans’ confidence in the news media dipping to historic lows, it might come as no surprise that a primary gripe the public has with outlets is their perceived biases. 

Now, new research out of the University of Pennsylvania lends some credence to these concerns — at least with regard to cable news networks.

After analyzing 10 years worth of content from CNN, Fox News and MSNBC, research revealed shifting media biases over the study window, while prime-time shows (airing between 7 and 9 p.m.) largely drove heightened polarization between the channels. Overall, Fox News tended to skew toward the right over the past decade while MSNBC and CNN moved left.

The team focused on visibility bias, assessing the perceived political leanings of guests who appeared on the networks. News anchor ideology was not included in the analyses and most news anchors do not make campaign contributions.

Longitudinal data were gleaned from the Stanford Cable News Analyzer from 2010 to 2021, which reports screen time of various political actors on cable news, authors explained. They then quantified any partisan leaning of those actors via past campaign donation behaviors. 

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“​​There has always been this assumption that media bias is fairly fixed,” said study co-author Yphtach Lelkes in a statement. Lelkes is an associate professor at the University of Pennsylvania’s Annenberg School for Communication. “But what we see is that it moves, and pretty quickly,” he added.  

Polarization between the networks was particularly acute in the period following the 2016 presidential election of former President Trump and continued to shift over time.

In addition, data showed the distance between CNN and MSNBC remaining largely unchanged, but “the relationship between Fox News and the other channels has polarized — growing increasingly distant from one another.”

In the past, the three stations used to track each other, Lelkes explained, adding that as one moved to the right or left, the other generally followed suit. But following the election of former President Trump, “they responded to events in the news by leaning away from each other and more strongly toward their respective ideologies,” he said.

Prime-time shows “Anderson Cooper 360” on CNN and “The Rachel Maddow Show” on MSNBC tended to skew more toward liberal points of view compared with shows airing at other times on the respective networks. Similarly, “Tucker Carlson Tonight” skews more toward the right than other Fox News shows. 

Morning and afternoon shows on each channel tended to include more hard news and fact-based reporting. 

An additional study published in July 2022 concluded Americans who receive their news primarily from television are less likely to venture outside their partisan camps than those who read news online. 

“Partisan news channels’ audiences are growing even as the TV news audience is shrinking,” the study concluded, noting “results suggest that television is the top driver of partisan audience segregation among Americans.”

The pair of studies detail a concerning trend of increasing partisan audiences for cable news outlets alongside these outlets becoming more extreme, researchers cautioned.

The team at the University of Pennsylvania hopes to make its data available to the public soon and pursue future research regarding questions on the role of ratings and viewer boycotts on networks’ bias shifts.

It also remains to be seen whether the gap between networks will shrink or grow wider indefinitely. 

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