The Lateral Orbitofrontal Cortex Mediates Stereotyping
Post by Leanna Kalinowski
The takeaway
Actions towards other individuals are often driven by assumptions about what they are like based on their group membership (i.e., stereotypes). Researchers have identified the lateral orbitofrontal cortex as a key brain region that mediates the effect of stereotypes on social behavior.
What's the science?
Stereotypes, defined as generalized beliefs about a category of people on the basis of gender, age, race, nationality, or occupation, often influence how individuals treat one another. It has previously been observed that stereotypes can be structured along two dimensions of trait perception: warmth, which is the degree to which people have good intentions toward others, and competence, which is the degree to which people are capable of acting on their intentions. Although the impact of stereotypes on social behavior is well-documented, it’s still unclear how traits inferred from social-group membership are represented in the brain, and how these neural representations guide social behavior. This week in PNAS, Kobayashi, and colleagues tested the impact of stereotypes on the distribution of resources in a social decision-making game.
How did they do it?
43 participants were asked to choose how to allocate monetary resources between themselves and a series of hypothetical recipients in a task called the Dictator Game. In each trial, the participants first viewed one piece of social-group information about a hypothetical recipient (e.g., “Occupation: Lawyer”). The researchers selected 20 social-group memberships to display, which were based on previous research that showed that these social-group memberships spanned a wide range of the warmth and competence dimensions.
The participants were then shown two options to allocate the funds. Option one was an equal allocation of money between the participant and recipient, while option two was either (1) advantageous inequity, which was an unequal division of money that favored the participant, or (2) disadvantageous inequity, which was an unequal division of money that favored the recipient. Each participant completed 80 trials each while brain activity was measured using functional magnetic resonance imaging (fMRI).
What did they find?
In advantageous inequity trials (i.e., trials that favored the participant), participants were less likely to choose the unequal allocation of money when the recipient’s warmth was higher. Conversely, in disadvantageous inequity trials (i.e., trials that favored the hypothetical recipient), participants were less likely to choose the unequal allocation of money when the recipient’s competence was higher. Taken together, these results suggest that inferences about other people’s traits exert strong effects on social-decision making.
Turning to the fMRI data, the researchers first conducted a representational similarity analysis, which looks for (1) brain regions where two recipients with similar traits display similar response patterns and (2) brain regions where two recipients with dissimilar traits display dissimilar response patterns. This analysis revealed that recipients’ warmth and competence are represented in the lateral orbitofrontal cortex (OFC), which has traditionally been associated with inference-based decision-making, along with two brain regions associated with mentalizing (i.e., temporoparietal junction & superior temporal sulcus). Finally, the researchers found that only activation of the lateral OFC predicted individual monetary allocation choices. Taken together, these results suggest that the trait representation in the lateral OFC contributes to allocation decisions.
What's the impact?
This study demonstrates that the effect of stereotypes on behavior is driven by inference-based decision-making processes in the lateral OFC. Future studies should investigate the role of the OFC in other types of inference-based decision-making, such as social projection and learning about traits from experience.