PROVIDENCE, R.I. [Brown University] — What causes two people from opposing political parties to have strongly divergent interpretations of the same word, image or event?
Take the word “freedom,” for example, or a picture of the American flag, or even the 2020 U.S. presidential election. A person who identifies politically as liberal vs. one who identifies as conservative will likely have opposing interpretations when processing this information — and a new study helps to explain why.
While previous theories posited that political polarization results from selective consumption (and over-consumption) of news and social media, a team led by researchers at Brown University hypothesized that polarization may start even earlier.
Their new study, published in Science Advances, shows that individuals who share an ideology have more similar neural fingerprints of political words, experience greater neural synchrony when engaging with political content, and their brains sequentially segment new information into the same units of meaning. In this way, the researchers said, they show how polarization arises at the very point when the brain receives and processes new information.
“This research helps shed light on what happens in the brain that gives rise to political polarization,” said senior study author Oriel FeldmanHall, an associate professor of cognitive, linguistic and psychological sciences who is affiliated with the Carney Institute of Brain Science at Brown University. Daantje de Bruin, a graduate student in FeldmanHall's lab, led the research and conducted the data analysis.
Previous research from FeldmanHall’s lab showed that when watching a potentially polarizing video about hot-button issues like abortion, policing or immigration, the brain activity of people who identified as Democrat or Republican was similar to the brain activity of people in their respective parties.
That neurosynchrony, FeldmanHall explained, is considered evidence that the brains are processing the information in a similar way. For this new study, the researchers wanted to get an even more detailed picture of why and how the brains of people in the same political party are able to sync up.
To do that, the team used a range of methods that they say have never before been used in conjunction with each other. They conducted a series of experiments with a group of 44 participants, equally split among liberals and conservatives, who agreed to perform various cognitive tasks while undergoing functional magnetic resonance imaging (fMRI), which measures the small changes in blood flow that occur with brain activity.