Your political views help determine which science books you buy
Our political leanings can influence plenty of our day-to-day choices, from the news we read and watch, to the Facebook friends we hide and the Tweets we like. It's no secret that people tend to gravitate toward ideas that reaffirm their worldview.
This filtering doesn't exclusively exist online. Even the paper-and-ink books we buy can reflect our political preferences -- particularly when it comes to books on science.
A new study found that people who buy conservative or liberal political books in the U.S. are equally interested in science books, but they pick works on starkly different topics.
SEE ALSO: Here’s how you create echo chambers on FacebookBuyers of liberal books tend to prefer books on basic sciences, such as physics and astronomy, while buyers of conservative books prefer applied sciences, such as criminology and geophysics, researchers found in a paper published Monday in Nature Human Behaviour.
Conservative book buyers were also more inclined to buy "peripheral" science books, meaning books that aren't considered mainstream science reading and express more of a political bent.
Credit: Darren McCollester/Getty Images 
Credit: Justin Sullivan/Getty Images Take, for instance, Rich Trzupek's How the EPA's Green Tyranny is Stifling America, or Steve Milloy's Green Hell. Peripheral liberal books included Bob Dean's Reckless: The Political Assault on the American Environment and Van Jones' The Green Collar Economy.
To the study's authors, this political split might be the analogue equivalent of a Facebook "echo chamber" that silences opposing views, or an "information bubble" that isolates news consumers from politically inconvenient truths.
"Even if there's a big pool of common ideas, people aren't consuming them evenly," said James Evans, co-author of the study and director of the University of Chicago's Knowledge Lab.
"The likelihood that political liberals and conservatives who are coming to the table to discuss a major problem in society are going to have exposure to the same kind of research, the same facts, is very limited," he said.
Via GiphyKelly Garrett, an associate professor at Ohio State University's School of Communications who was not involved with the research, said he disagreed with framing the results as further proof of information bias. Showing that liberals prefer books on basic sciences, or that conservatives tend to pick applied science books, doesn't necessarily mean consumers are willfully ignoring diverse viewpoints, he said.
"It's a really interesting study, but I don't like framing this as an echo chamber or a filter bubble. That's premature," Garrett said.
Books, books, books
Evans and his colleagues didn't survey actual book buyers. Instead, they studied U.S. purchasing behavior from the world's two biggest online bookstores: Amazon and Barnes & Noble. Neither company released internal sales data, so the researchers analyzed the algorithms that create up to 100 suggestions under the "Customers who bought this item also bought..." section.
The team collected nearly 26.5 million "co-purchase" links among 1.3 million books from Amazon.com. Then they divvied the books into three groups: political, science and non-science.
Credit: david ramos/Getty Images Among the 3,500 politically relevant titles, they identified 673 conservative books and 583 liberal books; some 2,300 "indeterminate" books were discarded. Researchers collected similar information from Barnes & Noble's co-purchasing network and found the same patterns.
A book was considered "science" if it was listed under science categories in the Library of Congress and Dewey Decimal classifications. Nearly 429,000 science titles were grouped into over two dozen high-level topics, which were then distilled into four main schools: humanities, physical sciences, life sciences, and social sciences.
Based on the data, they found conservative books were more likely to be co-purchased with books in applied sciences, such as medicine, law, and -- wait for it -- climatology. Yes, people associated with a political party whose leadership denies mainstream climate science are buying quite a few books on the topic.
Via GiphyFor Garrett, this finding undermines the idea of an echo chamber. "An echo chamber suggests that someone who doubts climate science should be trying to stay well clear" of the field, he said.
Liberal books were more likely to be co-purchased with books in basic science disciplines, such as zoology, anthropology and philosophy.
Some science topics were deemed "purple" if they were co-purchased by both the left and right. Perhaps paleontology and veterinary medicine can bridge this nation's political divides?
For Evans, the algorithms that connect buyers of political books to certain types of science books may be the bookstore equivalent of the Facebook News Feed: A digital microphone that amplifies the things you agree with while moving diverse or opposing views to the bottom of the pile.
Suggested reading for buyers of "Green Hell." Credit: screenshot/amazon.com 
Suggested reading for buyers of "Reckless: The Political Assault on the American Environment." Credit: screenshot/barnesandnoble.com "In the same way your friends online influence the news you read, these recommender engines send books that are like other parts of you," he said.
"And so you end up getting potential feedbacks that are concerning."
Yet despite rising worries that Americans are growing more narrow-minded, other research suggests we might not be living inside our own thought bubbles after all.
Separate studies using Nielsen TV viewership data, the web activity of more than 10,000 Americans over a year, plus the news choices of 10 million Facebook users all indicate we're not shutting ourselves off to disagreeable information. Another paper found the audiences for CNN and Fox News programs aren't completely separate, either.
Still, this study makes one thing clear: Science can't escape politics.
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