Racial bias happens in a heartbeat - literally

Signals from the heart can make the brain more prejudiced.

A number of studies have shown that people are more likely to misidentify harmless objects as weapons when they’re held by a Black person. Now, new research identifies a biological contributor to that effect. In the study, participants viewed pictures of suspects holding either a gun or a phone in a first-person-shooter task. Researchers monitored their heart activity, and found that racial bias in threat perception increased when the image was timed to flash during a heartbeat. This suggests that signals from the heart to the brain play a role in our fear response to racial stereotypes.

“We were motivated by the very grave statistics coming from the US, where unarmed Black individuals are twice as likely to be shot and killed by police officers as White individuals,” says senior author Manos Tsakiris. “Even though a lot of studies show that these biases exist, we lacked an understanding of the precise mechanism that may underlie this phenomenon.” Two contributors to the study had previously found that signals from the heart can selectively enhance fear and threat processing in the brain. That experience led the authors to look at whether this mechanism might play a role in racial stereotypes.

“Each time the heart beats, it activates receptors known as baroreceptors, which are stretched, pressure-sensitive receptors that get pinged when the heart ejects blood,” explains Sarah Garfinkel. “These send signals to the brain and activate the amygdala with every heartbeat. We know the amygdala is the part of the brain which deals with fear and threat processing.” Because of this mechanism, timing the images to match up with a heartbeat meant participants saw them when the amygdala was particularly active, and thus essentially primed for a fear response.

The findings suggest that that in the real world, the physiology and psychology of fear may mutually reinforce each other. When we feel threatened, our hearts speed up. “A faster, stronger heartbeat gives greater potential to tap into these signals, resulting in more stereotyped, racist behavior,” says Garfinkel.

Now that this biological contributor to racially biased fear has been identified, the question of how to mitigate it remains. The authors emphasize that a physiological mechanism doesn’t mean actions motivated by racial prejudice are unavoidable. The automatic reaction in the amygdala competes with other functions from the prefrontal part of the brain. Tsakiris explains: “You may be walking down a dark alley, see somebody coming towards you who may be from a different outgroup, and have this automatic activation of fear response. But at the same time, we don’t want to run away. We don’t want to behave in a racist way, so we control the processes and try to regulate the automatic activation.” Strengthening these controlled processes, for example through education or brain stimulation techniques, can help limit the effects of racial stereotypes.

Simply making people aware of how the heart signals the brain may also help. Research into the effects of signals from the heart on memory show that training people to be aware of their heartbeat can counteract the negative influence. And, of course, there are the social contributors to racism. The authors say the effect isn’t limited to fear rooted in racial prejudice, but rather represents a broader threat response. “In this case, we’re just tapping into a prevailing stereotype in society: that Black individuals are seen as more threatening,” says first author Ruben Azevedo. “We all know that to a very large extent, social stereotypes and racial stereotypes seem to be embedded in our culture.”

Image courtesy of Rosemarie Voegtli.