DELLWOOD, MO - AUGUST 09: People march from the Canfield Green Apartments in Ferguson where Michael Brown was killed following a memorial service marking the anniversary of his death on August 9, 2015 in Ferguson, Missouri. Brown was shot and killed by a Ferguson police officer on August 9, 2014.National Journal

The nation's reaction to the deaths of Samuel Dubose, Michael Brown, Eric Garner, Freddie Gray, and other Black men killed during police encounters in recent months, has been contentious and racially charged. While many blame the individual officers involved or even the entire police force, there is an even more far-reaching culprit — the stereotype that Black men are threatening.

Like any stereotype, the belief that all Black men are threatening is obviously not true.

"Black men may seem scary, not because they actually are, but because constructing a story about threat helps us to understand the negative feelings we may feel toward them."

But as many studies have shown, simply being aware a stereotype exists is enough for it to influence thinking and behavior. So regardless of whether the officers who killed Dubose, Brown, Garner, and Gray held negative attitudes toward Black people, their behavior was likely influenced by the stereotype that Black men are threatening.

The connection between threat and racial prejudice is no accident.

Threat is a well-known cause of prejudice according to theory and research in social psychology. What had been less clear is whether prejudice could actually come first and even cause the perception of threat.

To explore this important question, I conducted a series of experiments that conditioned participants to feel negatively or positively toward unfamiliar social groups. Group names were flashed on a computer screen alongside negative or positive images and words, and then participants answered questions about the groups. Because the groups were unfamiliar, there were no pre-existing stereotypes or beliefs about what these people were like.

Participants rated members of the negatively conditioned group as threatening, dangerous, and violent relative to the positively conditioned group, presumably to explain their negative feelings. These findings, published last month in the journal Group Processes and Intergroup Relations, suggest that prejudice causes threat perception, rather than the other way around.

Why does it matter if threat causes prejudice or if prejudice causes threat?

Take the stereotype that Black men are threatening, for example. A "threat causes prejudice" view assumes that it's something about them (in this case, Black men) that makes them scary, rather than something about us that makes us see them that way. When we understand that prejudice can come first, it becomes clear that threat perceptions are subjective. Black men may seem scary, not because they actually are, but because constructing a story about threat helps us to understand the negative feelings we may feel toward them.

Dylann Roof allegedly murdered nine parishioners at a historically Black church in Charleston, South Carolina, in June. The nation's unified response to this tragedy of Black lives lost contrasts starkly with its divided reaction to the deaths of Dubose, Brown, Garner, and Gray. One reason why the Charleston shootings are almost universally seen as hate crimes is that they took place in a church, while the victims were attending a prayer meeting — perhaps the prototypical image of nonviolence. Without a credible claim of threat to justify the attack, Roof's actions are readily viewed as racist. Here the stereotype that Black men are threatening cannot be invoked to justify the attack.

Why does it matter if threat causes prejudice or if prejudice causes threat?

By contrast, there was enough ambiguity in the details surrounding the death of Brown to convince a jury that Darren Wilson, the white Ferguson police officer who shot him, was acting in self-defense. The same ruling was made in the case of Garner. Not only did the stereotype that Black men are threatening likely escalate the officers' aggressive behavior at the time of confrontation, it was also called upon to legitimize their use of lethal force after the fact.

The problem with seeing the stereotype for what it is — a post-hoc explanation for feeling afraid — is that we are left with the uncomfortable, even terrifying realization that we are prejudiced.

The controversy over the Brown and Garner cases and the ensuing civil unrest reveals the slippery nature of threat perception. For those in agreement with the decisions, threat effectively served as justification of prejudice, absolving the perpetrators of blame. For those outraged by the decisions, however, the defendants' claims of self-defense were seen as nothing more than a thinly veiled excuse for racially motivated aggression.

Of course, there are many other factors that differentiate the Charleston killing spree from the deaths of Brown and Garner, but the comparison is informative for understanding the role of threat in relation to prejudice.

When we use threat to justify our fears toward a group of people, we allow ourselves to maintain our prejudice, often without even realizing that we have any biases at all. It's imperative that we recognize how threat can be socially constructed, and stop using the stereotype that Black men are threatening as an excuse for our hostile actions.

Social psychologist Angela Bahns is a professor at Wellesley College.

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