Implicit discrimination is subtle; in fact, a person who is implicitly discriminating may not even know it. That's because this discrimination comes from ideas, associations and preferences from people's subconscious minds. Proponents of implicit discrimination theory say that people have opinions and biases that they don't think about and may never acknowledge. However, these biases guide many choices and behaviors, including hiring decisions.
You mind makes associations all the time, especially when you first encounter something. The associations can be as simple as thinking cookies are good and thorns are bad. Many associations you know about and may even cultivate. For example, you may knowingly prefer roses to carnations. That's explicit discrimination. However, if you find yourself always favoring red roses without ever thinking they're your favorites, then you're implicitly discriminating.
Researchers found through the use of computerized implicit association tests that when people are required under time pressure to choose which of two images or phrases they prefer, their choices indicate their implicit biases. According to "Implicit Discrimination," a 2005 study by Marianne Bertrand et al., when people don't have time to control impulses and consider their choice, their natural preferences emerge. When the Bertrand team conducted further testing, researchers removed the time pressure and found that the longer people took to answer, the more they were controlling their impulses, rather than reacting from implicit biases.
Although no extensive studies are on how implicit discrimination plays into hiring, let alone decisions about how anti-discrimination law can or should address implicit discrimination, researchers posit that people's unconscious racial and ethnic associations affect their hiring decisions. The Bertrand study noted that several subjects displayed brain activity showing fear and anxiety when they saw images of black faces. Researchers feel these people had implicit biases that despite their conscious efforts may emerge in various parts of their lives.
Implicit discrimination sometimes refers to biases over implicit characteristics or abilities that can't be controlled. For example, when hiring for a construction worker or mover, a manager may prefer men to women because men typically have more upper body strength. The bias stems from a valid fact over which no one has control. Likewise, a short person may have an easier time working in a coal mine. In this case, discrimination is based on physical characteristics and inherent physical abilities.