Brain’s Social Network Implicated in Dehumanizing Others

By Rick Naurert PhD

May 12th, 2022
Medically reviewed by Paul Sietes, MD.

When individuals perform heinous acts, we all wonder what possessed such a person to act that way. New research suggests a failure in the part of the brain that’s critical for social interaction could explain the deeds.

Investigators at Duke University and Princeton University believe this brain function may disengage when people encounter others they consider disgusting. This perception allows an individual to “dehumanize” their victims — an action that allows an individual to believe the others are absent thoughts and feelings.

This theory also may help explain how propaganda depicting members of the Tutsi tribe in Rwanda as cockroaches and Hitler’s excoriation of Jews in Nazi Germany as “vermin” contributed to torture and genocide, the study said.

“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 lead author Lasana Harris, Ph.D. Harris co-authored the study with Dr. Susan Fiske, a professor of psychology at Princeton University.

Social neuroscience has shown through magnetic resonance imaging (MRI) studies that people normally activate a network in the brain related to social cognition — thoughts, feelings, empathy, for example — when viewing pictures of others or thinking about their thoughts.

However, when participants in this 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.

Researchers say this disconnect is puzzling as people will easily ascribe social cognition — a belief in an internal life such as emotions — to animals and cars, but will avoid making eye contact with the homeless panhandler in the subway.

“We need to think about other people’s experience,” Fiske said. “It’s what makes them fully human to us.”

Prior research has suggested that a lack of social understanding can occur when individuals do not acknowledge the mind of other people when imagining a day in their life. This misperception causes an individual to view them differently on traits that we think distinguish humans from everything else.

This latest study expands on that earlier work to show that these traits correlate with activation in brain regions beyond the social cognition network. These areas include those brain areas involved in disgust, attention and cognitive control.

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

In the study, 119 undergraduates from Princeton completed judgment and decision-making surveys as they viewed images of people. The researchers sought to examine the students’ responses to common emotions triggered by images such as:

a female college student and male American firefighter (pride);
a business woman and rich man (envy);
an elderly man and disabled woman (pity);
a female homeless person and male drug addict (disgust).

After imagining a day in the life of the people in the images, participants next rated the same person on various dimensions.

They rated characteristics including the warmth, competence, similarity, familiarity, responsibility of the person for his/her situation, control of the person over their situation, intelligence, complex emotionality, self-awareness, ups-and-downs in life, and typical humanity.

Participants then went into the MRI scanner and simply looked at pictures of people.

The study found that the neural network involved in social interaction failed to respond to images of drug addicts, the homeless, immigrants and poor people, replicating earlier results.

“These results suggest multiple roots to dehumanization,” Harris said. “This suggests that dehumanization is a complex phenomenon, and future research is necessary to more accurately specify this complexity.”

The study may be found in the Journal of Psychology.

Source: Duke University

Dr. Rick Naurert has over 25 years experience in clinical, administrative and academic healthcare. He is currently an associate professor for Rocky Mountain University of Health Professionals doctoral program in health promotion and wellness. Dr. Naurert began his career as a clinical physical therapist and served as a regional manager for a publicly traded multidisciplinary rehabilitation agency for 12 years. He has masters degrees in health-fitness management and healthcare administration and a doctoral degree from The University of Texas at Austin focused on health care informatics, health administration, health education and health policy. His research efforts included the area of telehealth with a specialty in disease management.