Blinded by Politics

It's hard not to make assumptions about people based on their political leanings. Accordingly, we may tread lightly when broaching immigration with a conservative pal—or gun shows with a liberal one. But overly broad inferences about others could prove costly.

Knowing someone's political beliefs, a recent paper contends, can affect how we assess that person's nonpolitical knowledge. In a pair of online experiments, participants responded to questions about political issues and learned the stances of several unseen "sources." They also did a run-through of a symbol-categorization task and saw whether the sources gave correct responses on it.

Later, as participants sought to win a small reward by completing the symbol task accurately, they were allowed to peek at how one of the sources had answered. To succeed, they should have simply turned to the sources who were best at the task. But politics appeared to color their choices. On average, they were no more likely to consult an accurate source who was politically different from them than they were to rely on a politically similar source whose responses were random.

When we perceive someone as similar to us, we may grant them believability "bonus points," says cognitive neuroscientist Tali Sharot at University College London, one of the study's authors. She suspects the findings reflect a halo effect: "If you think someone has a characteristic that you value, that spills over to other characteristics."

This bias could have real consequences, researchers suggest, if it leads us to write off valuable input from experts or media outlets based on their political bent. "We may feel that we have carefully reasoned our way through the issues, so if someone else has reached similar views, we might assume they are careful reasoners too," explains Ryan McKay, a psychologist at Royal Holloway University of London who reviewed the studies. "But that assumption may be mistaken."

Even social inferences that seem safe might be misleading. In one study conducted after the 2016 U.S. presidential election, Clinton voters inferred that immigration—an issue on which Trump was especially outspoken—was a more important factor for Trump voters than his supporters said it was. Quick judgments may prevent us from finding out what actually matters to people who vote differently. "I think the element of overconfidence is dangerous," says IESE Business School researcher Kate Barasz, who co-authored the study. "It allows us to sidestep a dialogue."