Neural Basis of Prejudice and Stereotyping
As social beings, humans have the capacity to make quick evaluations that allow for discernment of in-groups (us) and out-groups (them). However, these fast computations also set the stage for social categorizations, including prejudice and stereotyping.
According to David Amodio, author of the review I am summarizing:
Social prejudices are scaffolded by basic-level neurocognitive structures, but their expression is guided by personal goals and normative expectations, played out in dyadic and intergroup settings; this is truly the human brain in vivo.
But what is the role of the brain in prejudice and stereotypes? First, let’s start by defining and distinguishing between the two:
Prejudice refers to preconceptions — often negative — about groups or individuals based on their social, racial or ethnic affiliations whereas stereotypes are generalized characteristics ascribed to a social group, such as personal traits or circumstantial attributes. However, these two are rarely solo operators and are often work in combination to influence social behavior.
Research on the neural basis of prejudice has placed emphasis on brain areas implicated in emotion and motivation. These include the amygdala, insula, striatum and regions of the prefrontal cortex (see top figure). Speficifically, the amygdala is involved in the rapid processing of social category cues, including racial groups, in terms of potential threat or reward. The striatum mediates approach-related instrumental responses while the insula, an area implicated in disgust, supports visceral and subjective emotional responses towards social ingroups or outgroups. Affect-driven judgements of social outgroup members rely on the orbital frontal cortex (OFC) and may be characterized by reduced activity in the ventral medial prefrontal cortex (mPFC), a region involved in empathy and mentalizing. Together, these structures are thought to form a core network that underlies the experience and expression of prejudice.
In contrast to prejudice, which reflects an evaluative or emotional component of social bias, stereotypes represent the cognitive component. As such, stereotyping is a little more complex because it involves the encoding and storage of stereotype concepts, the selection and activation of these concepts into working memory and their application in judgements and behaviors. When it comes to social judgments, I find it useful to think of prejudice as a low road, and stereotypes as a high road (which recruits higher order cortical areas). For example, stereotyping involves cortical structures supporting more general forms of semantic memory, object memory, retrieval and conceptual activation, such as the temporal lobes and inferior frontal gyrus (IFG), as well as regions that are involved in impression formation, like the mPFC (see bottom figure).
Importantly, although prejudice and stereotyping share an overlapping neural circuitry, they are considered as different and dissociable networks. Also, it is important to remember that areas such as the mPFC, include many subdivisions that may contribute to different aspects of the network. This is important because these within structure subdivisions are usually not readily identifiable in neuroimaging studies. Anyway, if you want to learn more about the specifics of these network and obtain real world examples of these networks at work, read the full review article (see below).
Amodio, D. (2014). The neuroscience of prejudice and stereotyping. Nature Reviews Neurocience. doi: 10.1038/nrn3800