A brain part tied to social interaction might prompt a person to commit horrific atrocities, especially if it becomes dysfunctional.

This flaw also may help explain how propaganda depicting Tutsi ethnic group in Rwanda as cockroaches and Hitler's classification of Jews in Nazi Germany as vermin contributed to torture and genocide.

‘When we encounter a person, we usually infer something about their minds. Sometimes, we fail to do this, opening up the possibility that we do not perceive the person as fully human,’ said Lasana Harris, neuroscientist and assistant prports the Journal of Psychology. 

But when participants in thisofessor of psychology at Duke University, who led the study. 

Social neuroscience has shown through MRI studies that people normally activate a network in the brain related to social cognition -- thoughts, feelings and empathy, for example -- when viewing pictures of others or thinking about their thoughts, re study were asked to consider images of people they considered drug addicts, homeless people and others they deemed low on the social ladder, parts of this network failed to engage, according to a statement of Duke and Princeton universities.

The result is what the researchers call ‘dehumanised perception,’ or failing to consider someone else's mind. Such a lack of empathy toward others can also help explain why some members of the society are sometimes dehumanised, they said.

‘We need to think about other people's experience. It's what makes them fully human to us,’ said Susan Fiske, study co-author and professor of psychology at Princeton.

For this latest study, 119 undergraduates from Princeton completed judgement and decision-making surveys as they viewed images of people.