The human brain is predisposed to learn negative stereotypes, according to research that offers clues as to how prejudice emerges and spreads through society.
The study found that the brain responds more strongly to information about groups who are portrayed unfavourably, adding weight to the view that the negative depiction of ethnic or religious minorities in the media can fuel racial bias.
Hugo Spiers, a neuroscientist at University College London, who led the research, said: “The newspapers are filled with ghastly things people do … You’re getting all these news stories and the negative ones stand out. When you look at Islam, for example, there’s so many more negative stories than positive ones and that will build up over time.”
The scientists also uncovered a characteristic brain signature seen when participants were told a member of a “bad” group had done something positive – an observation that is likely to tally with the subjective experience of minorities. “Whenever someone from a really bad group did something nice they were like, ‘Oh, weird,’” said Spiers.
Previous studies have identified brain areas involved in gender or racial stereotyping, but this is the first attempt to investigate how the brain learns to link undesirable traits to specific groups and how this is converted into prejudice over time.
The study’s 22 participants were shown snippets of information about fictitious social groups, such as “a member of the Kitils kicked a stray cat” or “a member of the Pellums gave their mother a bouquet of flowers”. The two main groups were secretly designated as “good” and “bad”, with two-thirds of the information fitting the group stereotype and one-third bucking the trend.
Brain scans taken as the participants built up a picture of the tribes showed that activity in a brain region called the anterior temporal pole matched their acquisition of prejudice. By measuring this brain activity, it would be possible to “mathematically track prejudice second by second” to determine a person’s current level of bias, according to Spiers.
The scans also revealed that the brain did not respond equally to good and bad information.
Once the participants had seen enough snippets to feel reassured that a group were essentially goodies, brain activity in the anterior temporal pole quickly tailed off. But it continued to respond strongly to the negative snippets about the behaviour of the “bad” group.
“The negative groups become treated as more and more negative,” said Spiers. “Worse than the equivalent for the positive groups.”
Bastian Schiller, a neuroscientist at the University of Freiburg in Germany who was not involved in the work, said: “They really investigated the process of stereotype formation. Previous studies looking at implicit bias have found activity in similar regions and so it makes sense.”
The scans also revealed a characteristic signature of activity in the brain’s prefrontal cortex, which lit up when participants were given information that went against the stereotype. Again, this response was stronger when a member of a “bad” group did something good than for the reverse.
“It’s a bit like learning there’s some really nice people working in Isis,” said Spiers. “We found a very strong activity in a network of brain areas, in particular the prefrontal cortex, which is involved in detecting anomalies in the world.”
The findings did not reveal whether negative stereotypes are more difficult to reverse, but Spiers predicts that this is likely to be the case, based on the findings.
Scientists believe that stereotypes serve a purpose because clustering people into groups with a variety of expected traits helps us navigate the world without being overwhelmed by information. “[Negative information] may have been more important for your own survival in ancient times,” said Schiller. “It might be more important to store that in your brain.”
In future, scientists predict that it may even be possible to uncover differences in brain structure that explain why some people hold racist or sexist views. “It may just be that certain brains are configured to be more flexible and able to unlearn prejudice and others less so,” said Spiers. “That might be driven by the environment, say if someone grows up in a very racist household, the brain might become trained to be less flexible in its thinking.”