While some would believe dehumanizing someone is a way of expressing dislike, new findings suggest that the two may actually be different psychological processes.

The study titled "Denying humanity: The distinct neural correlates of blatant dehumanization" was published in the Journal of Experimental Psychology on May 31.

"When people are dehumanizing others, they are mobilizing different brain regions than when they are registering their dislike," said co-lead author Dr. Emile Bruneau from the University of Pennsylvania.

To put into perspective, you may love a puppy or an infant while acknowledging that they don't have a fully realized human mind. And you may dislike a colleague but still acknowledge them as human.

In the experiment, participants were asked to judge various groups while functional magnetic resonance imaging (fMRI) was used to observe their brain activity. The groups they looked at included Americans, Muslims, Roma, puppies, surgeons, homeless people, Europeans, mice, etc.

Dislike was measured using a "feeling thermometer scale," as people would rate how warm or cold they felt toward a specific group. Dehumanization, on the other hand, was measured using the well-known Ascent of Man image. Here, participants were asked where they would place each group on the scale which showcases the stages of evolution.

It turned out that dehumanization and dislike were processed by two completely separate regions of the brain.

"Brain regions sensitive to dehumanizing other groups were not sensitive to dislike. And brain regions activated when registering dislike for those same groups were not activated when thinking about how human those groups are," Bruneau explained.

After all, interventions to reduce conflict between two groups are typically focused on getting the opposing groups to like each other and find something to relate to in the other. This could help people recognize what is referred to as "human essence," by David Livingstone Smith, an associate professor of philosophy at the University of New England, Australia.

If one does not recognize human essence in another, it becomes easy to characterize them (sometimes, whole populations) as less-than-human. "This principle is crucial for understanding dehumanization because it implies that someone can appear to be human appearance but lack a human essence," Smith wrote.

"This is how European colonists conceived of Native Americans, and how slave owners conceived of their human chattel. This is how the Nazis conceived of Jews, and how Rwandan Hutus conceived of their Tutsi neighbors."

The authors of the new study also reported that many people did not hesitate to admit that they found a certain group to not be fully human or evolved. 

One of the reasons he studied dehumanization was due to his interest in "intervening to reduce intergroup hostility," Bruneau stated. While he found the psychological difference between dehumanization and dislike to be academically interesting, he hoped to see the research put to practical use for the development of interventions.