At last count, more than 600,000 of Myanmar’s Muslim Rohingya minority had fled the country for Bangladesh. Ever since Rohingya militants attacked Myanmar police outposts, resulting in a dozen deaths in August 2017, Myanmar security forces have begun a campaign of ethnic cleansing. They have burnt down hundreds of Rohingya villages, and murdered, raped and beheaded the Rohingya they have encountered.

What has driven Myanmar security forces to engage in this act of ethnic cleansing? Do they fail to recognise the inherent humanity of their victims, or do their acts represent an excess of morality, morality that can be satisfied only by punishing a fellow human? What’s the motive that spurs on this violence?

A popular explanation for horrific violence is that perpetrators see victims as little more than animals or objects, and so they feel little remorse in abusing, torturing or killing them because it is easier to hurt an animal or break an object than it is to hurt a human being. This process of dehumanisation has been invoked to explain acts of violence ranging from the Holocaust and the prisoner abuses at Abu Ghraib to the ethnic violence against the Rohingya people. However, our recent research suggests that this explanation is mistaken. After all, the failure to recognise someone’s humanity predicts indifference toward their welfare, not an active desire and delight in bringing about their suffering. To understand the active desire to cause pain and suffering in another person, we have to look to a counterintuitive source: human morality.

As we show in the aforementioned research, published in the Proceedings of the National Academy of Sciences in 2017, dehumanisation allows us to commit instrumental violence, wherein people do not desire to harm victims, but knowingly harm them anyway in order to achieve some other objective (imagine shooting a stranger in order to steal his wallet). However, dehumanisation does not cause us to commit moral violence, where people actively desire to harm victims who deserve it (imagine shooting your cheating spouse). We find that moral violence emerges only when perpetrators see victims as capable of thinking, experiencing sensations and having moral emotions. In other words, when perpetrators perceive their victims as human.

This is not to say that perpetrators do not hold extremely disgusting and racist views of their victims. They might also insult their victims by explicitly comparing them to apes and other animals. But when we manipulate dehumanisation experimentally, and measure it in ways that do not tap into explicit racism, we find no relationship between dehumanisation and moral violence. We first demonstrated this by asking participants to report how much they approved of different kinds of violent practices, such as drone strikes, capital punishment of murderers and sweatshop labour. Then, we asked the participants about the victims in these examples. Can the victims think and reason? Can they feel pain and suffering? Are they capable of love and compassion? Or hate and anger? We used these questions to assess whether people thought of victims as completely human, independent of other negative attitudes they might hold toward them.

What we found was that dehumanising victims predicts support for instrumental violence, but not for moral violence. For example, Americans who saw Iraqi civilians as less human were more likely to support drone strikes in Iraq. In this case, no one wants to kill innocent civilians, but if they die as collateral damage in the pursuit of killing ISIS terrorists, dehumanising them eases our guilt. In contrast, seeing ISIS terrorists as less human predicted nothing about support for drone strikes against them. This is because people want to hurt and kill terrorists. Without their humanity, how could terrorists be guilty, and how could they feel the pain that they deserve?

We also conducted experiments in which we asked people to imagine harming someone either for money or as punishment for an immoral act. In one experiment, we found that participants expressed less support for breaking someone’s thumb for $1 million when the person was described using humanising language (eg, ‘John is ambitious and imaginative, but also high-strung and insecure’), just as dehumanisation theories predict. However, the use of humanising language did not change support for breaking the thumb of a pimp who recruits young women into prostitution.

In another experiment, we found that, after imagining pricking someone’s finger for $10, people saw the person they harmed as less human, again supporting theories that people dehumanize their victims to ease guilt over harming them. In contrast, we found that imagining pricking someone’s finger as punishment for immoral behaviour did not change their perception of the person’s humanity. In a few cases, we even found that participants justify harming evildoers by seeing the person they harmed as more human.

Many people believe that it is only a breakdown in our moral sensibilities that causes violence. To reduce violence, according to this argument, we need only restore our sense of morality by generating empathy toward victims. If we could just see them as fellow human beings, then we would do them no harm. Yet our research suggests that this is untrue. In cases of moral violence, our experiments suggest that it is the engagement of our moral sense, not its disengagement, that often causes aggression. When Myanmar security forces plant landmines at the Bangladesh border in an attempt to kill the Rohingya minorities who are trying to escape the slaughter, the primary driver of their behaviour is not dehumanisation, but rather moral outrage toward an enemy conceptualised as evil, but also completely human.

Does that mean that there is no role for dehumanisation in violence? Absolutely not. The indifference caused by dehumanisation is what enables so many people to look away and do nothing while horrible atrocities occur. Every time Myanmar’s leader, Aung San Suu Kyi, fails to condemn the atrocities committed by Myanmar’s security forces, or questions whether they have even occurred, the effects of the dehumanisation of minorities is clear. Dehumanization may not cause Myanmar’s security forces to kill, but it does enable the rest of us to stand aside and do nothing.

A version of this story first appeared in Behavioral Scientist in August 2017.