A neuroscientist explains the unconscious racial biases behind deadly police shootings

Owing to Facebook’s new live stream feature, most of the world has seen the video depicting the moments after Philando Castile, a 32-year-old cafeteria manager, was shot and ultimately killed by a police officer. The shooting occurred not even 48 hours after another black male was shot and killed by a cop in Baton Rouge, Louisiana. In both cases, the victims had concealed handguns. And in both cases, the video footage appears to indicate that the individuals who were shot actually presented no legitimate threat to the officers.

What it comes down to is a difference in perception. In the subconscious minds of many police officers, an armed white man is just a citizen exercising a constitutional right, while a black man carrying a gun is an imminent danger.

Following the event in Minnesota, even the state’s governor, who is a white male, told the press that he didn’t believe the incident would have occurred had the driver been white. Similar sentiments were expressed by President Obama shortly after.

Of course this does not mean that police forces across America are composed of open racists that actively conspire to take black lives. However, what has been proven by countless empirical studies is that, in general, brains respond differently to black males in ways that create a perceived threat out of an otherwise neutral event — a process that often occurs outside of conscious awareness.

It doesn’t matter if the police officer does not consider himself a racist, or holds no overt racist beliefs or attitudes. It is an ugly fact of nature that an intrinsic racial bias that influences automatic reactions may be hardwired into his or her brain. Racism can accompany racial biases, or be driven by them, but a racial bias can exist independent from conscious racism as well. In fact, some studies show that the implicit racial bias towards blacks can even exist in black individuals themselves.

We can be sure that this racial bias is real and robust because scientists have actually measured it directly in a number of ways—physiologically, cognitively, and behaviorally—and under a number of different conditions.

At the neural level, the bias manifests itself as an enhanced electrical response in the brain region associated with threat processing and fear. An fMRI study published in the Journal of Cognitive Neuroscience found increased activity in the amygdala when white participants were shown images of black male faces on a computer screen relative to white male faces. Greater amygdala activation is indicative of an unconscious negative reaction to black faces. Since past studies have shown that damage to the amygdala extinguishes fear, the results imply that white Americans are vulnerable to perceiving black men as threatening when no threat exists.

At the cognitive level, visual attention is biased towards black faces with neutral expression as if they were threatening. Decades of research has shown that all individuals, regardless of race, tend to direct their attention towards threatening stimuli—like snakes, spiders, or angry faces—more quickly than they do towards non-threatening images. This is because evolution has shaped our attentional systems to rapidly detect threat as a survival tactic. A 2008 study in the Journal of Experimental Social Psychology found that, in much the same way, white participants orient their attention toward black faces faster than to same-race faces. This effect occurred even in those who reported no racist beliefs. Additionally, since the faces were only presented for 30 milliseconds in this study, it is unlikely that the race-related attention bias is a conscious phenomenon.

At the behavioral level, the racial bias is revealed by the fact that non-black participants are faster at categorizing negative words when they follow pictures of black faces relative to white faces. This type of experiment is known as the Implicit-Association Test, and it has been used to demonstrate implicit racial biases so many times that the existence of the general effect is not even disputed amongst psychologists. These results suggest an unconscious mental association between African Americans and negative things or concepts in the brains of whites.

While these findings are disturbing to those of us who detest racism, they provide us with information that can be used to help us understand and overcome these problematic built-in biases.

It seems to me that progress is never made because the nation can’t agree on the root cause of the types of shootings that just occurred in Louisiana and Minnesota. While a good portion of people believe that widespread, systemic racism exists within our police forces that results in the senseless loss of black lives, a comparable portion of the country believes that cops are responding appropriately and without racist intent. And when police officers and officials don’t accept that race plays a critical role in these sorts of incidents, no steps are taken to correct the problem.

Hopefully now we can acknowledge the evidence and all agree on the existence of implicit racial biases that drive unconscious reactions which can result in the unwarranted killing of black men. This empirically-based insight should motivate systemic changes in the police selection and training processes. Cognitive tasks like the Implicit-Association Test and those that detect threat-related attention biases should be used to identify officers that might be prone to unconscious, race-biased behavior. All officers should be taught about the concept of implicit racial biases so that they may be more self-aware when faced with a potentially lethal situation that could easily be avoided.

This is not about placing the blame on any particular group or individual. This is about acknowledging science. Biological and psychological predispositions uncontrollably influence our split-second decisions. It is not time for endless debate that goes nowhere. It is time to educate and implement this knowledge into police-training programs and policies. Only when this kind of change begins can the nation truly begin to heal.