Why Republicans and Democrats Can't Feel Each Other's Pain Mr Raymond (Raymond Weekes) / Getty Images Shakespeare asked rhetorically whether Christians and Jews are not "hurt with the same weapons, subject to the same diseases, heal'd by the same means, warm'd and cool'd by the same winter and summer?" The same can be said of Republicans and Democrats, but if you ask people on opposite sides of the aisle to try to empathize with one another, they tend to consider their rivals as not equally human. That's not a mere observation of election-year political antics, but a finding from scientific research. Led by Ed O'Brien, scientists from the University of Michigan crafted a study on inter-party empathy based on prior data on the emotion, which finds that our ability to empathize is greatly affected not only by whom we're trying to empathize with, but also by our own physical and emotional states. Physical states, especially, are difficult to transcend. If you've ever packed for a tropical vacation in the dead of winter and had difficulty imagining yourself basking on a warm beach when it's freezing at home, you've experienced the challenge most people face when trying to take the perspective of another - or even of your own future self. When our visceral state is overwhelming, we tend to project the same feeling onto everyone else: if I'm cold, then you must be cold too. Studies also find that thirsty people perceive others as being equally dehydrated, and those who feel frightened similarly think everyone else must be afraid too. Even exam cheaters project their own willingness to cut corners on fellow test takers. But this kind of empathy doesn't always extend to everyone. History is filled with examples of warriors who were brutal to their enemies, but kind to their comrades. Biologically speaking, the hormone most associated with empathy - oxytocin - has been found to increase people's feelings of warmth and generosity toward their friends and family while simultaneously increasing prejudice against outsiders. MORE: "Love Hormone" Oxytocin Is Choosy, But Not Necessarily Racist The Michigan study, published in Psychological Science, combined these various threads and sought to determine whether people's political affiliations and their individual states of thirst or cold would affect their ability to empathize with another person. For the first experiment - conducted in January 2011 in Michigan, when both partisan sentiment and the weather were bitter - 120 students were recruited. Half were approached at a bus stop when the temperature dropped to as low as -14 degrees; the rest were interviewed in a cozy library. They were told they were participating in research on reading comprehension. All of the participants read a short story about a hiker who was described either as a left-leaning, pro-gay rights Democrat or a right-wing Republican who took the opposite position. Taking a break from a campaign, the hiker had become lost on a mountain without adequate food or water or appropriate clothing for wintry weather. For female participants, the hiker was described as female; for men, the hiker was male. Participants were asked which feeling - being thirsty, hungry or cold - was most unpleasant for the hiker and which item he or she most regretted not packing. The participants were also asked about their political beliefs and affiliations and whether they felt the hiker was similar to them. Not surprisingly, feelings of similarity were almost exactly correlated with political agreement. People who were interviewed outside at the bus top were most likely to focus on the hiker being cold - but only if they felt the hiker was similar to them. Ninety-four percent of those at the bus stop who felt similar to the lost hiker said the cold was the worst part of his or her experience; in comparison, only 57% of those who were interviewed indoors said the same. If participants disagreed with the hiker's politics, however, their own personal physical state had no bearing on their response: people chose the cold in equal numbers, regardless of where they were interviewed. Similar results were found with regard to regrets: 81% of those at the bus stop whose politics fell in line with the hiker's said he or she likely regretted not bringing the right clothing most of all, while only 37% of those indoors said this. But again, the participant's personal state didn't affect responses when Democrats were considering lost Republican hikers, or vice versa. MORE: Mind Reading: Psychologist Simon Baron-Cohen on Empathy and the Science of Evil In another experiment, this time related to thirst, the researchers found similar results: 141 students were given eaten salty snacks to eat, half with a glass of water and half without. Among participants who shared the hiker's party affiliation, 71% of those who were thirsty said that his or her lack of water would matter most, while only 20% of those who got a glass of water focused on thirst. Once again, people's own thirst had no effect on their consideration for the hiker's water needs, if the hiker was labeled as a political enemy. The finding is disheartening because it suggests that our prejudices affect the processing of our emotions on a deep and completely unconscious level. The authors write: These consequences suggest a surprising limitation in our capacity to empathize with people we disagree with or differ from... Firsthand painful experiences apparently do not translate into appreciating similar pain felt by dissimilar others. This sad conclusion may help explain, at least in part, why politicians continue to talk past each other and fail to cooperate, even where there are obvious areas of agreement. The similarities between Mitt Romney's conservative-think-tank designed health plan and Obama's health-care plan come to mind. There are exercises aimed at increasing empathy: some research suggests, for example, that simply spending time together in neutral or pleasant settings can help increase understanding between groups. Indeed, prior Congresses have actually crossed party lines to socialize. But while it's doubtful that a non-partisan retreat or more social contact would change politicians" attitudes today, for the sake of our children, let's hope they find a way to work together. MORE: How Not to Raise a Bully: The Early Roots of Empathy Maia Szalavitz is a health writer at TIME.com. Find her on Twitter at @maiasz. You can also continue the discussion on TIME Healthland's Facebook page and on Twitter at @TIMEHealthland.