Lecture 9.2: Racial Bias & Prejudice

Modern Racism Scale

A questionnaire where you rate sentences on a five point scale. It's a measure of explicit racism because you're directly reporting how you feel.

Dual-Process Model of Weapon Bias

Both automatic impulses and intentional responses feed into behavioral response. Your cognitive control is responsible for balancing these two inputs to influence your response. When people have full control of their behavior, they respond as intended. When control is impaired, automatic impulse drives responses.

Joshua Correll's Bias in Weapon Perception Video Game

Correll developed a video game in which there are a series of images of young men (some armed and some unarmed) set against realistic backgrounds like parks or city streets. The player's goal is to shot any and all armed targets, but not to shoot unarmed targets. Half of the targets are black and half are white. People generally don't make a lot of errors, but when they do make errors, there tends to be racial bias. Later, they repeated the study with eye tracking. Showed that participants relied on more ambiguous information when responding to stereotypic targets. For counterstereotypic targets, they achieved greater clarity before responding. Implications for police shootings.

Lieberman et al. (2005)

Follow-up study to the Phelps study, comparing black and white participants. They found that amygdala activity for white subjects was greater when looking at black faces than white faces. They found this effect was not only present but bigger for African American participants. However, the study had an extremely small subject pool (only 11 white participants and 9 African American participants). So it's hard to draw large conclusions. IAT scores show that black people generally do not have a negative anti-black bias, but also don't really show strong in-group preference the way white people do (likely because of cultural context)

Biases in Weapon Perception

In one study, they flash an image of a face and an image of either a gun or a hand tool. Then you see a visual mask that interrupts your visual system from further processing it. Results show that participants are more likely to falsely report a gun following a black face.

Brain Regions Involved in Racial Bias

The amygdala has been linked to the automatic threat response that we've discussed. The FFA is involved in the rapid identification of other race individuals. The ACC is thought to detect conflict between implicit race attitudes and conscious intentions to be nonbiased. When such conflicts are detected, the DLPFC may regulate negative evaluations.

Telzer et al. (2013)

This fMRI study looked at amygdala activity while participants were viewing faces of different races across a range of ages (cross sectional study). For white faces, the response is pretty flat -- it doesn't change as a response to age. For unfamiliar black faces, on the other hand, amygdala activity increases with age. It's really around 13 or 14 years old that this becomes a significant effect. They did find, however, that children with more diverse peers show dampened amygdala activation in response to black faces.

Implicit Association Test (IAT)

This is a response time test. First, you have to sort faces by pressing one key for white faces and another for black faces. Then, you sort words by pressing one key for good and another for negative words. Then, you'll have to sort faces and words mixed together. This stage has two conditions: one condition has one key for good words + white faces and one key for negative words + black faces; the other condition has one key for good words + black faces and one key for negative words + white faces. The average time differential between the two conditions is called the IAT effect and it represents the strength of an attitude. The IAT has shown that implicit bias is systematic and widespread.

The "Other Race" Effect

This is the effect that, when you show people faces and then later do a recognition test, they tend to do really well for faces of their own race and pretty poorly for faces of other races. fMRI studies have shown that there is more FFA activity when looking at same race faces. This has to do with the better perceptual fluency -- you're better at processing faces of your own race because you've probably interacted with more people of that race. EEG recordings show differences between looking at a same race face and other race face as early as 170 ms after face onset. Means that the other race effects emerge very quickly. Larger N170 ERP amplitudes were seen in response to viewing black faces vs. white faces in subjects with stronger implicit prejudice and in subjects who felt anxious about appearing biased.

Phelps et al. (2000)

This was one of the first fMRI studies on implicit bias. They scanned white participants as they viewed unfamiliar black and white faces (looking specifically at the amygdala). Then, participants completed the modern racism scale and the implicit association test. The IAT effect correlated with their amygdala activity. But there was no correlation to explicit prejudice. They also measured a startle eye-blink response (showed participants a black or white face and then played a loud noise to startle them). Participants startle in a more robust way when looking at a black face - perhaps their fear response was sort of primed. In addition, eye-blink response was correlated to IAT effect, but not to individual differences in explicit racism. These threat responses were only present when white participants were shown unfamiliar black faces.

Startle Eye-Blink Response

You are exposed to a startling noise and the muscles around your eyes are monitored as you blink. By exposing you to different stimuli first, we can measure how much your fear response is primed.