The next time your friend displays remarkable openness to their opposite political camp’s ideas, you might try pinching them.

Okay, we don’t really recommend that. But new evidence shows that people with increased sensitivity to pain are also more likely to endorse values more common to people of their opposite political persuasion. It doesn’t stop there. They also show stronger support for the other camp’s politicians, and, get this — more likely to vote for Donald Trump in 2020 if they are liberal, or Joe Biden if they are conservative.

Even lead researcher Spike Lee, an associate professor of marketing at the Rotman School of Management, who is cross appointed to the University’s Department of Psychology, was pinching himself at the revelations.

“We were honestly not expecting to see this kind of cross-aisle effect of pain sensitivity,” says Lee, who started thinking about the research idea while enjoying the oral freezing experience in his dentist’s chair. “When we first found it, we thought it might be a fluke. That’s why we ran a replication study. We found it again. We ran extended replications and follow-up studies. We kept finding it.”

The connection is perhaps not so surprising considering that we experience pain — whether it’s the physical pain of stubbing our toe or the social pain of getting bulldozed in a political argument — in a similar part of the brain. We can also experience pain vicariously by witnessing other people’s distress or perceiving a social injustice.

Lee and his research colleague, psychology graduate student Cecilia Ma, ran seven different studies with more than 7,000 U.S.participants to test competing theories of what pain sensitivity does to our perceptions of moral and political threats — does it heighten them across the board, only affect threats to the sensibilities we personally hold dear, or make us more sensitive to somebody else’s?

To gauge pain sensitivity, they used a validated self-report instrument called the Pain Sensitivity Questionnaire, as well as asked participants about their political orientation and conducted an assessment of the foundations of their moral outlook.

Liberals with higher pain sensitivity showed greater affinity for typically conservative moral values such as loyalty and authority. Pain-sensitive conservatives meanwhile showed more support for values such as care and fairness, usually associated with liberals. The pattern continued when participants were asked about their 2020 voting intentions and their support for Democrat and Republican politicians.

So, along with being quicker to yelp “ouch!” does that mean the pain-sensitive are also confused about their own political orientation? Lee cautions that “it’s not that their profile of moral sensitivities shifts from ‘only supporting our side’ to ‘only supporting the other side.’ Instead, they tend to be more supportive of both sides’ views.”

While the research doesn’t give a clear solution for how to find middle ground in a politically polarized society, it does shed light on a previously unexplored influence on our moral and political views. Far from being purely rational, most people’s views “are infused with moral feelings, with emotional reactions to what’s right and wrong,” says Lee. “The better we understand the bases of a person’s moral feelings, the better we can explain and predict their political views.”

The study appears in the Journal of Personality and Social Psychology: Attitudes and Social Cognition.