In February 1999, four New York City police officers were on patrol in the Bronx when they saw a young black man standing on a stoop. They thought he looked suspicious. When they pulled over, he retreated into the doorway and began digging in his pocket. He kept digging as the police shouted at him to show his hands; a few seconds later, the man, Amadou Diallo, the 23-year-old immigrant from Guinea, was dead, hit by 19 of the 41 bullets that the police fired at him. What Diallo was reaching for was his wallet. He was going for his ID as he stood on the steps of his own apartment building.
Diallo's story, and the officer's fatal pre-judgment of him, is recounted in Malcolm Gladwell's 2005 bestseller Blink.
Gladwell, and the social psychologists whose work he draws upon, explores Diallo's case as an example of that grey area between deliberate violence and an accident, propagated by non-conscious, or implicate biases.
The officers did discriminate against Diallo, but the prejudice they acted on may have been driven by something more subtle than simple hatred.
And that's an important thing to think about. Yes, there are lots of overtly bigoted people and policies at work all over the world, but what we're interested in today is the more insidious, non-conscious automatic bias, and how it can affect our behavior.
The fact is, our implicit biases affect the way we relate to others in a very real way. Our race, gender, age, religion, or sexual orientation can make the difference between whether we get a job or not, a fair paycheck, or a good rental, or whether we get randomly pulled over or shot and killed for reaching for a wallet.
In the last two episodes, we've examined how we think about and how we influence one another, but social psychology is also about how we relate to one another.
Like what factors might cause us to help another person, or harm them, or fear them? What are the social, cognitive, and emotional roots of prejudice, racism, and sexism, and how do they shape our society? These are some of the aspects of ourselves that are the hardest and most uncomfortable for us to explore, which is why they're so important to understand.

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We've all been unfairly judged in our time, and let's not pretend that we haven't done our fair share of uninformed judging too.
Like it or not, prejudice is a common human condition.
Prejudice just means "prejudgment." It's an unjustified, typically negative attitude towards an individual or group.
Prejudicial attitudes are often directed along the lines of gender, ethnic, socioeconomic status, or culture, and by definition, prejudice is not the same thing as stereotyping or discrimination, although the three phenomena are intimately related.
People may distrust a female mechanic. That's a prejudicial attitude, but it's rooted in a stereotype, or over-generalized belief about a particular group.
Although it's often discussed in a negative way, stereotyping is really more of a general cognitive process that doesn't have to be negative. It can even be accurate at times.
Like, I have the stereotype that all crows have wings, injuries and birth defects aside. And that happens to be true.
But on the negative side, your prejudice against female mechanics may be rooted in some inaccurate stereotype about women's skills with a socket wrench.
And when stereotypical beliefs combine with prejudicial attitudes and emotions, like fear and hostility, they can drive the behavior we call discrimination.
So a prejudiced person won't necessarily act on their attitude. Say you believe in the stereotype that overweight people are lazy. You may then feel a prejudiced distaste when you see someone who appears overweight.
But if you act on your prejudice, and, say, refuse to hire them for a job or don't let them sit at your lunch counter, then you've crossed over into discriminating against them.
The former apartheid system of racial segregation in South Africa, the Nazis' mass killing of Gypsies, Jewish people, and other groups, and centuries of bloodshed between Protestants and Catholics, are all extreme examples of violent bloodshed and discrimination.
The good news is that in many cultures, certain forms of overt prejudice have waned over time. For example, in 1937 only 1/3 of Americans said they'd voted for a qualified woman to be president, while in 2007, that figure was up to nearly 90 percent.
But of course more subtle prejudices can still linger.
In the past, we've talked about dual-process theories of thought, memories, and attitudes, and while we're aware of our explicit thoughts, or implicit cognition still operates under the radar, leaving us clueless about its effect on our attitudes and behavior.
In the same way, prejudice can be non-conscious and automatic. And I mean it can be so non-conscious that even when people ask us point-blank about our attitudes, we unwillingly or unknowingly don't always give them an honest answer.
Do you think that men are better at science the women? Or that Muslims are more violent than Christians? Or that overweight people are unhealthy?
Our tendency to unwittingly doctor our answers to questions like these is why we have the implicit association tests, or IAT. The test was implemented in the late 1990s to try to gauge implicit attitudes, identities, beliefs, and biases that people are unwilling or unable to report.
You can take the IAT online and measure your implicit attitudes in all kinds of topics, from race, religion, and gender to disability, weight, and sexuality. It's basically a timed categorization task.
For example, the age-related IAT looks at implicit attitudes about older vs. younger people. In it, you might be shown a series of faces, old and young, and objects, pleasant and unpleasant, like pretty flowers vs. a pile of garbage.
You're then asked to sort these pictures, so you'd press the left key if you see a young face or a pleasant object, and press the right key if you see an old face or an unpleasant object. That's the stereotypic condition.
Your keystrokes correspond to stereotypical pairs; in this case, associating good stuff with youth and bad stuff with older age.
Then the test asks you to do the same thing in a counter-stereotypic condition, pressing the left key if you see a young face or an unpleasant object and the right key if you see an old face or a pleasant object.
The core of the test is your reaction time. Are you faster at sorting when you're working with a stereotypical pairing than you are with counter-stereotypical pairings? If that's the case, even though you may think you're unprejudiced, you've got an implicit association between youth and goodness, which, as you might guess, might have some implications towards how you think or act towards older people.
The test is widely used in research, and contrary to what some critics think, it's surprisingly predictive of discriminatory behavior in all kinds of experimental settings.
So that's one way to measure subtle, implicit prejudice. But obviously, overt prejudice is far from dead. That's why discrimination studies are prominent in social psychology research, and they can also predict, sometimes with scary accuracy, how discrimination might show up in broad social patterns, like wage inequality and job opportunity gaps.
For instance, the 2012 Yale study led by social scientist Corinne Moss-Racusin demonstrated that science faculty across the country systematically discriminated against female science students. In a double-blind study, a representative sample of science faculty members were asked to hire a fictional student applicant for a lab-manager job.
When the applicant's name was Jennifer, instead of John, they viewed her as less competent, were less likely to hire her, offered her less money, and were less likely to mentor her.
And this prejudice was even exhibited by women faculty members.
And that's an important point. People on both sides of the stereotype tend to respond similarly, with the subjects of stereotypes themselves holding the same stereotypical implicit attitudes or engaging in the same discriminatory behavior.
So when we say that stereotypes are pervasive, we mean pervasive.
Now it's all too easy to hold up examples of how people are prejudiced, but the real root of the issue is why they are. Here are a few possibilities:
For one, prejudices can come up as a why of justifying social inequalities. This happens when people on both sides of the power and wealth spectrum start believing that people get what they deserve, and they deserve what they get. This is called the just-world phenomenon.
Prejudices can also be driven by the "us vs. them," or as social psychologists often call it, the in-group-outgroup phenomenon. Whether you're in the soccer stadium, or political arena or school lunchroom, or, you know, in the comments of this video, dividing the world into in-groups and outgroups definitely drives prejudice and discrimination.
But an in-group identity also gives its members the benefits of communal solidarity and a sort of safety in numbers. This in-group bias, or tendency to favor your own group at the expense of others, is powerful, even when it's totally irrational. One common social psychology exercise on in-group favoritism involves dividing a class into two arbitrary groups, say, those wearing sneakers and those not wearing sneaker. Each person sits with his or her group and is told to list differences between themselves and the opposing group.
The lists usually start out pretty tame, but become more strident as the grow longer. Eventually, you have sneaker-wearing kids saying that they're just smarter than the people without sneakers. The kids who don't have sneakers say that the other kids are trashy and low-class.
Soon enough, each group has inflated itself and derided the opposing group, even though the division between the two was essentially meaningless to begin with.
Little exercises like this illustrate the power of any in-group-outgroup distinction in creating conflict between groups, and that brings us to the psychological nature of conflict itself.
History is littered with examples of how the us vs. them mentality has fueled violence in warfare, which is exactly what we'll be talking about next time.

Today, you learned about how prejudice, stereotyping, and discrimination affect how we interact and relate to one another. You learned how prejudice can often be non-conscious and automatic and how tools like the Implicit Associations Test help reveal and measure it. We also looked at the implications of the in-group-outgroup phenomenon, and how it can lead to strong in-group violence that often turns aggressive.

This episode of Crash Course Psychology was sponsored by Shane Barr, whose young adult sci-fi adventure book, Reset, is available on Amazon.

Thanks to watching, especially to all of our Subbable subscribers who make Crash Course possible. To find out how you can become a supporter or lead sponsor like Shane, just go to Subbable.com/CrashCourse.

This episodes was written by Kathleen Yale, edited by Blake de Pastino, and our consultant is Dr. Ranjit Bhagwat. Our director and editor is Nicholas Jenkins, our script supervisor and sound designer is Michael Aranda, and the graphics team is Thought Cafe.