Unconscious bias has recently become a hot topic, with high-profile incidents of bias reported around the world. In a study published last week in Social Cognitive and Affective Neuroscience, scientists show that the brain not only is unconsciously biased towards people based on appearance but also forms biases based on what we know about the person.
Peoples’ brains are naturally biased in favor of people who are the same as them—a behavioral trait scientists call ‘in-group favoritism.’ The opposite is also true: people are often naturally biased against those who are not the same as them, called ‘out-group derogation.’ “If knowledge gained from our social environment can implicitly bias how we perceive each other, this should hold true to characters in movies as well,” says first author Mamdooh Afdile from Aalto University.
Afdile created a 20-minute stimulus from the film Priest that explored biases in two social groupings: heterosexual and homosexual men. At the beginning of the movie, the viewer gets the impression that the priest is heterosexual and falling in love with a woman. But at the 10-minute mark, the viewer finds out the priest is actually in love with another man.
To see if watching the movie biased the viewers subconsciously, Afdile flashed the face of the protagonist repeatedly for a brief duration of 40 milliseconds before and after showing the movie. Even though the viewer wouldn’t have been able to notice that they were shown a person’s face—much less recognize the person—their subconscious brain responded to the flashed face based on whether or not they had become biased. Using functional MRI, the researchers were able to visualize how people’s biases could be changed with new information.
The subconscious response to the face of the protagonist after seeing the movie, compared to before seeing it, differed significantly between the two social groups. The results from the heterosexual group showed a very mild negative bias response while the results from the homosexual group showed a very strong ‘in-group’ response in empathy and favoritism.
“This study shows the brain can be biased based on learned knowledge and not only by external factors,” Afdile explains. “By combining movies with subliminal measurement, we can now investigate the subconscious brain in ways that were extremely difficult before.”