Whenever the news delivers stories about murder, rape, or torture, a person would react by saying, "How can people do that?" People react this way partly because of disbelief, but mostly because it is inhumane. For the question no one can answer, new research may shed some light on the topic of how humans can be inhuman.

When it comes to heinous, dehumanizing acts, the part of the brain critical for social interaction does not engage, thereby effectively dehumanizing others by failing to acknowledge their thoughts and feelings, according to lead author Lasana Harris, an assistant professor in Duke University's Department of Psychology and Neuroscience and Center for Cognitive Neuroscience.

Harris explained that whenever someone encounters a person, they usually infer something about their minds. However, at times, people fail to do this therefore, people do not perceive others as fully human.

MRI showed that people normally activate a network in the brain related to social cognition, through thoughts, feelings, empathy, when viewing pictures of others or thinking about their thoughts. However, when participants in the study were shown images of people they considered drug addicts, homeless people, and others they deemed low on the social ladder, parts of this network in the brain failed to engage.

In addition, findings show that people easily ascribe social cognition, which is the belief in an internal life such as emotions, to animals and cars while avoiding making eye contact with those they consider low on the social ladder.

Further in their latest study, 119 undergraduates from Princeton were asked to complete judgment and decision-making surveys as they viewed images of people. Examining the students' reactions to the images, participants found that:

- An image of a female college student and male American firefighter invoked pride

- Image of a business woman and a rich man caused envy

- An elderly man and disabled woman got pity

- A female homeless person and male drug addict received disgust

In light of this, coauthor Susan Fiske, a professor of psychology at Princeton University, pointed out the need to think about other people's experience as it makes them fully human.

With all this talk of the brain switching off social cognition and understanding how the brain processes this, academically, what does it mean to dehumanize?

Dehumanization is actually a psychological process wherein opponents view each other as less than human, thus not deserving of moral consideration, Michelle Maiese reported in BeyondIntractability.org.

Despite the concept of morality and justice, it is psychologically necessary to dehumanize enemies in order to legitimize increased violence or justify the violation of basic human rights, in times of war for example.

With this mentality, dangers like stigmatizing groups as evil, morally inferior, or worse, not fully human arise. And when this occurs, persecution of others become psychologically acceptable, as dehumanization is directly linked to the increase of the likelihood of violence.