At its most extreme, discrimination can take the form of violence against an individual or members of a racial group. From the Civil War on, for many decades, lynching was an act of violence used primarily to intimidate, punish, and terrorize blacks in the South. Many other societies, such as South Africa, Rwanda, and Bosnia, have also experienced violent forms of racially and ethnically charged discrimination, including genocide, which is the deliberate and systematic killing of a category of people.

Acts of racial or ethnic discrimination can be classified as individual or as institutional and structural. Individual discrimination is an action carried out by an individual or small group that harms one or more individuals based on their group membership. An employer refusing to hire blacks, a landlord who does not rent apartments to Mexican Americans, or a group of teenagers who paint swastikas on a Jewish synagogue are all examples of individual-level discrimination. In these cases, individuals or small groups take purposeful actions to negatively affect members of specific racial or ethnic groups.

Discrimination may not always be intentional, however. Recent psychological research suggests that our behaviors are influenced by many kinds of implicit (or “unconscious”) prejudice, involving stereotypes that can be activated in our minds without our being aware of them (Greenwald and Banaji 1995). Even people who consciously reject racial stereotypes may nonetheless be influenced by them. Psychologists have discovered this through various experiments, the most well-known of which is the Implicit Association Test, which you can take for yourself at http://projectimplicit.net. This test has repeatedly shown that when given a task to complete, people are generally slowed down if it involves recognizing nonstereotypical associations (such as matching the words “black” and “pleasant”) and can usually speed up when required to make stereotypical matches (such as “white” and “pleasant”). Although negative implicit bias is widespread—nearly 85 percent of whites taking the test are estimated to have some degree of unconscious racial prejudice—research suggests it can be reduced through introspection and positive exposure to the target group, in much the same way that thought exercises and habituation can help people control powerful emotions like fear and anger. In fact, implicit prejudice may be to emotion what explicit (or conscious) prejudice is to thought (Quillian 2006). Implicit bias seems to come into play when it is difficult for individuals to regulate themselves (for example, in split-second decisions or through their body language), whereas explicit prejudices may have a greater impact on deliberate or premeditated actions (like a speech). Recent tragedies where police offers have fatally shot unarmed black men raise distressing questions about how important implicit prejudices may be.

People are not the only actors who may discriminate, however. Sociologists maintain that institutions can also be discriminatory. Institutional (or structural) discrimination occurs when the actions or policies of organizations or social institutions exclude, disadvantage, or harm members of particular groups. Jim Crow—a system of laws and social norms that governed interactions between blacks and whites in the American South in the early twentieth century—represented an institutionalized system of discrimination. Schools, housing, transportation, and public facilities all formally engaged in discriminatory practices by keeping blacks and whites separate and in grossly unequal facilities. South Africa’s system of apartheid is another example of this institutional form of discrimination where whites were able to secure their social position by excluding nonwhites from the majority of institutions.

As in the case of individual discrimination, institutional discrimination may or may not be intentional. An example of intentional institutional discrimination would be the United States’ 1790 naturalization law, which explicitly stipulated that only white immigrants could become citizens. An example of unintentional discrimination could be the federal sentencing guidelines that penalize individuals in possession of crack cocaine more heavily than those who possess powder cocaine. Although the guidelines do not explicitly refer to race—and so do not appear to be intentionally discriminatory—the fact that powder cocaine is used disproportionately by whites and crack by blacks means that African Americans are more likely, than whites, to face the heavier penalties dictated by the sentencing guidelines. As this example suggests, however, it is not easy to determine whether institutional discrimination is intentional or not. Even though the guidelines do not overtly base criminal sentences on race, they may well have been adopted because they were likely to have a disproportionately harsh impact on African American offenders. The difficulty of determining when an individual or institution has intended to put certain groups at a disadvantage has led to the precedent in the U.S. legal system that it is not always necessary to prove negative intentions in order to arrive at a finding of discrimination. Instead, statistical evidence of what is called the “disparate impact” of an institution’s policies—for example, that an employer’s hiring or wage-setting procedures lead to worse outcomes for some groups than others—may suffice to demonstrate discrimination in the courtroom, regardless of whether intentionality can be ascertained. Similarly, sociologists consider institutions to be discriminatory if the ultimate impact of their actions is to exacerbate inequality, regardless of whether or not that was the original intention behind them.