Neural oscillations underlying the expression and modulation of intergroup bias

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School of Science | Doctoral thesis (article-based) | Defence date: 2024-06-19
Degree programme
66 + app. 124
Aalto University publication series DOCTORAL THESES, 110/2024
Humans can be distinguished from robots by their ability to select all images containing a car regardless of the make, model, or picture angle. This basic human function, effortlessly sorting complicated information into clear categories, enables us to navigate in the constantly changing world. However, the tendency to categorize others into social groups can lead to stereotyping, prejudice, intergroup bias, and in worse cases discrimination and violent conflicts. After decades of research on intergroup relations using surveys to assess explicit self-reports and psychological tests to uncover automatic implicit processes, neuroscientific studies have found neural markers for processes that are not necessarily captured with the traditional measures of intergroup bias. This thesis presents work that uses magnetoencephalography (MEG) to examine the expression of intergroup bias in neural oscillations and its dependence on the urgency and conflict level of the intergroup context. Neural oscillations are examined in three different settings: political polarization in Israel, immigration support in Finland, and negativity against covid-19 vaccine hesitancy in Finland. The findings shed light on distinct context-dependent neural intergroup bias processes. In Israeli politics, two neural mechanisms activate asymmetrically for political leftists and rightists and relate to explicit and implicit behavioral assessments respectively. Investigating young Finns' reactions to stereotypical Muslim faces shows that while explicit and implicit psychological measures are unable to capture the subtle prejudice in this sample, a biased neural reaction related to face processing surfaces. Two vaccination datasets reveal how quickly the neural bias can change, with distinct neural processes emerging during the pandemic and in its aftermath. After pinpointing the neural mechanisms that activate during intergroup bias processes, this thesis investigates the question of whether and how these mechanisms can be modulated using prejudice-reducing intergroup interventions. One such intervention that is tested in this thesis is paradoxical thinking: exposing people to ideas that are consistent with their existing beliefs but taken to a wildly exaggerated, even absurd, level. The studies find that the paradoxical thinking intervention effectively reduces neural bias and moreover, the neural processes activating during the intervention can predict the change in explicitly reported attitudes towards the outgroup. Overall, the results of this thesis increase knowledge of the neural underpinnings of intergroup bias and propose strategies for reducing said bias.
Supervising professor
Jääskeläinen, Iiro, Prof., Aalto University, Department of Neuroscience and Biomedical Engineering, Finland
Thesis advisor
Levy, Jonathan, Dr., Aalto University, Department of Neuroscience and Biomedical Engineering, Finland
social neuroscience, intergroup bias, magnetoencephalography, neural oscillations, intergroup interventions
Other note
  • [Publication 1]: Kluge, Annika*; Adler, Eliyahu*; Nir, Lilach; Halperin, Eran; Sams, Mikko; Levy, Jonathan. 2024. Asymmetry in political polarization at multiple levels of bias. Political Psychology, advance online publication. ISSN: 1467-9221. *Equal contribution.
    DOI: 10.1111/pops.12967 View at publisher
  • [Publication 2]: Kluge, Annika; Zebarjadi, Niloufar; Tassinari, Matilde; Lin, Fa-Hsuan; Jääskeläinen, Iiro; Jasinskaja-Lahti, Inga; Levy, Jonathan. Supportive, but biased: perceptual neural bias towards outgroup faces is sensitive to minor reservations in the support of outgroup assimilation. Submitted for peer review in the year 2024
  • [Publication 3]: Hautala, Annika; Kluge, Annika; Hameiri, Boaz; Zebarjadi, Niloufar; Levy, Jonathan. 2022. Examining implicit neural bias against vaccine hesitancy. Social Neuroscience, volume 17, issue 6, pages 532-543. ISSN: 1747-0919.
    DOI: 10.1080/17470919.2022.2162119 View at publisher
  • [Publication 4]: Kluge, Annika; Levy, Jonathan. Narrative consistency impacts neural polarization. Submitted for peer review in the year 2024.
    DOI: 10.31234/ View at publisher
  • [Publication 5]: Kluge, Annika; Somila, Niko; Lankinen, Kaisu; Levy, Jonathan. 2024. Neural alignment build-up during outgroup intervention predicts future change of affect towards outgroup. Cerebral Cortex, volume 34, issue 4, bhae125. ISSN: 1460-2199.
    DOI: 10.1093/cercor/bhae125 View at publisher