Numerous reports have highlighted how fake news creators began targeting conservative readers after finding them receptive to stories that reinforced their existing worldview. As one fake news creator told NPR, "We've tried to do [fake news with] liberals. It just has never worked, it never takes off. You'll get debunked within the first two comments and then the whole thing just kind of fizzles out."
A Buzzfeed analysis found that three main conservative Facebook pages were roughly twice as likely as three leading liberal Facebook pages to publish fake or misleading information.
There are cases of liberals circulating fake news stories, to be sure. During the presidential campaign, false stories about Tiffany Trump avoiding her father's kiss after a debate and older sister Ivanka saying she would mace Trump if he weren't her father spread quickly across social media. And some studies have shown confirmation bias -- our tendency to manipulate new information to support our existing beliefs -- doesn't have an ideological preference.
Still, while the apparent one-sidedness of the fake news ecosystem is striking, some researchers of partisan psychology say it's not particularly surprising. A robust body of academic research has sprung up in the past decade or so, documenting the different ways conservatives and liberals process the world.
Measuring the differences
Psychologist John Jost of New York University is one of the pioneering researchers in this realm. In a forthcoming book chapter, Jost and some colleagues analyze decades of research on political psychology and find that a number of personality traits are strongly correlated with conservatism. One in particular -- a so-called "need for cognition" -- speaks to why fake news creators have found a receptive audience among conservatives.
"Need for cognition" is measured by assessing people's agreement with statements like, "I find satisfaction in deliberating hard and for long hours" or "thinking is not my idea of fun." A measurement of people's affinity for critical thinking, in short.
Jost reviewed 40 studies on differences in this need for cognition between liberals and conservatives. Of those, 25 showed a "significant, negative" association between need for cognition and right-wing orientation. In all but three of the others, there was a similar negative association but it wasn't statistically significant.
In other words, liberals were slightly more predisposed to think critically than conservatives. As Stefan Pfattheicher of Ulm University put it in an email to me, conservatives "are less reflective in information processing, especially when information is consistent with [their] own worldviews."
In a small study earlier this year, Pfattheicher posed nonsensical statements like "hidden meaning transforms unparalleled abstract beauty" and "attention and intention are the mechanics of manifestation" -- to 196 supporters of various U.S. presidential candidates. He then asked them to rate how "profound" the statements were on a scale of 1 to 5, from "not at all" to "very profound."
While the study was not nationally representative, he found a significant correlation between support for Ted Cruz, Marco Rubio or Donald Trump and the favorable assessment of the meaningless statements. The relationship was the strongest for Cruz supporters in his sample. Conversely, he found no significant relationship between support for Democratic candidates and susceptibility to the nonsensical sentences.
Pfattheicher also found that individuals who identified as more conservative were more likely to be duped by nonsense than liberals.
Both Pfattheicher and Jost say that any cognitive differences aren't necessarily about intelligence. "This seems to be more a matter of motivation to process information (or news) in a critical, reflective thinking style than the ability to do so," Pfattheicher said in an email.
In other words, in Pfattheicher's reading, conservatives may be perfectly able to do the kind of critical thinking and cognitive exploration that would lead them to be more skeptical of nonsense and fake news -- they just choose not to, preferring instead to seek out information that allows them to make quick decisions that reinforce their existing views.
Looking for similarities
Not all social scientists are convinced that conservatives and liberals process the world in meaningfully different ways. Daniel Kahan, a Yale professor of law and psychology, says his research has found that people on the right are no more vulnerable to political bias than those on the left.
Kahan used a measure of cognitive style called the "cognitive reflection test." It posed three quantitative questions that assess a person's ability to resist blurting out the first (wrong) answer that comes to mind.
For instance, one of the questions asks: "If it takes 5 machines 5 minutes to make 5 widgets, how long would it take 100 machines to make 100 widgets?" Your impulse might be to say "100 minutes." But in fact, the correct answer is 5 minutes -- each machine produces a widget every five minutes.
"Bottom line," Kahan said in an email, "there's ample evidence of politically biased information processing across the entire ideological spectrum."
But Jost points out that several other studies using the cognitive reflection test in recent years did show evidence of partisan differences.
"There are now 11 other studies that have obtained significant differences in the predicted direction: overall, liberals do tend to perform better than conservatives on measures of cognitive reflection," Jost said in an email.
Kahan says he's not familiar with most of those studies but he points to other research he's done suggesting that people who score higher on cognitive reflection tests are actually more likely to engage in politically motivated reasoning.
"So were it true that liberals scored higher [on these tests], we'd expect them to display more, not less, political bias in their information processing," he said in an email.
Other social science research has found that politically motivated responses to evidence can depend partially on the subject matter -- conservatives react more skeptically toward evidence on things like climate change and evolution, while liberals are more skeptical when it comes to nuclear power and fracking.
"Of course, there is issue by issue variability when it comes to motivated reasoning," Jost said. But, he added, this wouldn't contradict his findings on different conservative and liberal cognitive habits. "There can be ideological differences in general, as well as reversals on specific issues," he said.
The research into personality traits, combined with the reports on the rise of fake news within the conservative internet, suggests that there are measurable, objective differences in how liberals and conservatives view the world -- and that savvy snake oil salesmen can exploit those differences for money and recognition.
"If anything," Jost said, "these new reports [of fake partisan news] suggest that the asymmetry may be even greater in the 'real world' than what we have been seeing in the lab."
Correction: An earlier version of this article included an incorrect answer for the sample Cognitive Reflection Test question.