Public defence in the field of Neuroscience and Biomedical Engineering, MID Gloria Mendoza-Franco

Title of the thesis: Decoding dynamic neural patterns of intergroup emotional responses

Thesis defender: Gloria Mendoza-Franco 
Opponent: Associate Professor Tal Kenet, Harvard University, United States
Custos: Professor Iiro Jääskeläinen, Aalto University School of Science

The mechanisms that explain how the brain distinguishes between “us” and “them” are fundamentally linked to the origins of ingroup favoritism, prejudice, and discrimination. When individuals are identified as members of an outgroup, perceptions of threats to the existence, power, or success of one’s own group can be triggered. As a result, different outgroups evoke different emotions that shape behavioral tendencies and serve specific social functions. These intergroup emotions are influenced by stereotypes and contextual factors. A better understanding of the neuroscience of these emotions, and of how context modifies them, is still needed. Recent advances in neuroimaging techniques, such as functional magnetic resonance imaging (fMRI) and the use of machine learning algorithms for data analysis, make it possible to identify patterns of neural activity associated with specific emotional states and examine their temporal evolution. This approach, known as time-resolved decoding, offers a promising avenue for investigating intergroup emotions. In this thesis, we investigated how neural patterns of emotions evolve during simulated encounters with people from different groups. To do this, we used 360-degree videos featuring individuals from diverse nationalities, each representing specific stereotypes in Finland. We also manipulated two contextual variables: interpersonal distance and the actors’ emotional expressions. This allowed us to examine how these factors affected emotional responses. Using time-resolved decoding, we evaluated the emotions that were triggered during these encounters. We also analyzed the role of the amygdala and its subregions in processing the simulated encounters. The amygdala is a brain region traditionally associated with the evaluation of threat, stereotypes, and salience, making it a strong candidate for closer examination. The findings showed that all stereotypes elicited a broad range of emotions. They also suggest that both interpersonal distance and emotional expressions influenced how stereotypes were perceived, which in turn affected intergroup emotions. The amygdala analysis indicated that different subregions may be involved in processing threat perception and social salience. Overall, this research shows that time-resolved decoding can be a useful tool for studying intergroup emotions and contributes to a better understanding of how emotional brain patterns respond during social interactions between groups.

Keywords: intergroup emotions, fMRI time-resolved decoding, MVPA, SCM, amygdala subnuclei, threat perception, prejudice, intergroup threat, emotional expressions

Thesis available for public display 7 days prior to the defence at Aalto University's public display page.