A video game study could show how the human brain justifies murder.

The new study looked at how people can become killers in certain situations, showing how brain activity varies according to whether or not killing is seen as justified.

Participants in the study played video games in which they imagined themselves to be shooting innocent civilians (unjustified violence) or enemy soldiers (justified violence). Their brain activity was recorded via functional magnetic resonance imaging (fMRI) while they played.

Monash University researcher Dr Pascal Molenberghs, from the School of Psychological Sciences, said the results show how people in certain situations, such as war, are able to commit extreme violence against others.

“When participants imagined themselves shooting civilians compared to soldiers, greater activation was found in the lateral orbitofrontal cortex (OFC), an important brain area involved in making moral decisions,” Dr Molenberghs said.

“The more guilt participants felt about shooting civilians, the greater the response in the lateral OFC. When shooting enemy soldiers, no activation was seen in lateral OFC.”

Essentially, the neural mechanisms that are usually associated with harming others become less active when the violence is seen as justified.

“The findings show that when a person is responsible for what they see as justified or unjustified violence, they will have different feelings of guilt associated with that – for the first time we can see how this guilt relates to specific brain activation,” Dr Molenberghs said.

The researchers hope to further investigate how people become desensitised to violence and how personality and group membership of both perpetrator and victim influence these processes.

The research report is accessible here.