Since the outset of the most recent Israeli-Palestinian conflict in Gaza, criticism has been leveled against the news media’s coverage of the crisis. A number of reporters have expressed their frustrations about there being no obvious way to please both sides. Regardless of their best efforts to cover the conflict objectively and fairly, reporters receive “a deluge of complaints” about biased or unbalanced reporting.

Research on media psychology shows that this tendency to see bias – even in objective news coverage – is far from uncommon. A landmark 1985 study on TV news coverage of the 1982 Christian militia massacre of Muslim refugees in Lebanon was the first research to document “the hostile media effect,” when people on both sides of an issue perceive that the news is biased against their interests. In this study, pro-Israel and pro-Arab college students viewed identical news coverage—as in the exact same thing. But here’s the kicker: both groups believed the coverage was biased against their side.

Thirty years later, these effects persist across a variety of issues and events including abortion, genetically modified foods, immigration, labor strikes, and political elections. Why, it wouldn’t surprise us if some of you were already seeing bias in this very article!

How is it that people on both sides of an issue can be so convinced that they are the ones being slighted? The answer lies in intergroup communication, the study of how people psychologically and behaviorally respond to social groups. We often romanticize the idea that we treat other people as unique individuals, but myriad studies suggest that it’s incredibly common to view them primarily as members of a larger group. People love to categorize themselves and others by group membership – male or female, gay or straight, Republican or Democrat, cat people or dog people. Psychologically, thinking in terms of groups provides a handy mental shortcut for sizing up ourselves and other people.

When we categorize, we tend to favor in-groups (the groups in which we see ourselves as members) and disfavor out-groups. Because the news media reaches a wide audience, any portrayal of our in-group that seems unfavorable is interpreted as a threat to our in-group’s image. The pride we feel for our in-groups motivates us to defend them against image threats. Here’s where the hostile media effect comes in. Partisans, people on one side of an issue, tend to cope with this threat by calling into question the accuracy or balance of the news coverage. Blaming a source for being biased is an easy way for people to reconcile views of their group that are inconsistent with their own views.

The stronger the connection people feel with their in-group, the stronger this hostile media effect is. Recent experiments by Tilo Hartmann and Martin Tanis at the University of Amsterdam found that after reading the exact same newspaper article on abortion, those most strongly identifying with their pro-choice or anti-abortion group were also people who believed the story was more biased against their own position. The study also found that if people had been told that their in-group has less creative intelligence than the out-group, they perceived the article as being even more biased against their in-group. This shows that when people feel like their group is already at a disadvantage, they are even more defensive against coverage that’s inconsistent with their own positive self-perceptions.

The tendency for partisan people to see news bias, regardless of whether it’s reality or not isn’t just something that frustrates Jon Stewart on The Daily Show, it’s an effect that can have negative consequences for democracy. In Israel, for instance, these perceptions have been found to weaken public trust in democracy and make people more resistant to efforts for compromise. Also, when opposing groups of people who feel passionately about an issue both attack media coverage, this can also make it more difficult for people in the middle to find information about the issue.

But intergroup processes don’t necessarily have to be divisive. Research also suggests that hostile media effects can be reduced if people have the right group mentality. Scott Reid, a professor of Communication at University of California, Santa Barbara, conducted a series of experiments showing that groups of Republicans and Democrats actually perceived less hostile bias against their in-group if, before evaluating news coverage, they were reminded of being Americans, instead of being reminded of their specific political party membership. Because these partisans were made to think about a common, shared in-group identity instead of a partisan in-group identity, they didn’t feel as defensive of their positions.

Unfortunately, journalists covering hot-button issues like the Middle East conflict are unlikely to see a reduction in complaint mail about news bias any time soon. But the good news is that when we think we smell news bias, we might be able to check our own intergroup biases at the door if we deliberately think less about what the media is doing to “us” versus “them” and instead, think more about how we all are being affected.