About

Christopher Sebastian Parker is a Professor in the Department of Political Science at the University of California, Santa Barbara. His specialization includes American Politics, Identity, Race, Ethnicity, and Public Opinion. He earned his Ph.D. from the University of Chicago in 2001. Professor Parker's research explores significant themes in American political life, with a focus on social change, racial dynamics, and reactionary politics. His first book, Fighting for Democracy: Black Veterans and the Struggle Against White Supremacy in the Postwar South, examines the role of black veterans in the civil rights movement and has received the American Political Science Association's Ralph J. Bunche Award. His second book, Change They Can't Believe In: The Tea Party and Reactionary Politics in America, investigates the beliefs, attitudes, and behaviors of the Tea Party movement, earning the APSA award for the best book in Race, Ethnicity, and Politics. He is also working on a forthcoming book titled The Great White Hope: Donald Trump, Race, and the Crisis of American Democracy, which analyzes the causes and political consequences of Trump's election. Professor Parker's scholarly articles have been published in prominent journals such as the Journal of Politics, Political Research Quarterly, Perspectives on Politics, and others. His work has been featured in major media outlets including The New York Times, Washington Post, CNN.com, and MSNBC, among others. He is actively engaged in research that critically examines race, identity, and political reaction in contemporary America.

Research topics

• Political Science
• Sociology
• Pathology
• Internal medicine
• Law
• Medicine
• Political economy
• Endocrinology
• Clinical psychology
• Genetics
• Radiology
• Gastroenterology
• Psychiatry
• History

Selected publications

• Placental blood-flow velocity quantification from diffusion MRI

  Proceedings on CD-ROM - International Society for Magnetic Resonance in Medicine. Scientific Meeting and Exhibition/Proceedings of the International Society for Magnetic Resonance in Medicine, Scientific Meeting and Exhibition · 2025-09-16

  article

  Motivation: Estimating blood flow velocity in capillary beds lacking voxel-scale coherence is challenging with current imaging techniques. Altered blood flow in small-scale placental capillaries is a key factor affecting the health of pregnant women and their fetuses. Goal(s): Estimating fetoplacental blood velocity directly from diffusion MRI. Approach: We perform Monte Carlo dMRI simulations with perfusion in synthetic capillary systems, training a machine learning algorithm to recover parameters like flow velocity from generated signals. This trained algorithm then estimates these parameters from in-vivo diffusion MRI of human placentas. Results: Our approach estimates placental blood velocities and diffusivities, yielding values comparable with published data. Impact: Our approach estimates blood velocity from existing diffusion MRI data, reflecting placental blood flow conditions and potentially helping to diagnose diseases like pre-eclampsia. This approach could also be applied to organs where blood velocity is clinically significant.

  PublisherDOI

• Exploring the Motivations of the MAGA Movement

  2025-06-19 · 1 citations

  book-chapterOpen access1st authorCorresponding

  Abstract The Make America Great Again (MAGA) movement burst on the scene with the most recent candidacy of Donald Trump in 2016. Many believe MAGA to be sui generis, something unseen prior to the current moment in American politics. This isn’t the position of the authors. Drawing on original survey data, this essay explores long-standing hypotheses on what drives the reactionary right in America. Materialist, class-based hypotheses are pitted against ones rooted in preference for social conformity (authoritarianism), and more symbolic explanations rooted in identity (e.g., racism, status threat, Christian nationalism). The authors find that at least here, explanations emphasizing class and social conformity have no explanatory power once identities related to symbolic politics are taken into account. The results add to the rapidly emerging literature on the social psychology of reactionary movements, further clarifying the declining position of class-based explanations when it comes to right-wing movements. More important for the present volume, the results support the claim in the conservative dilemma that symbolic politics are a more useful means of animating the mass public on the right than economic concerns.

  PublisherDOI

• Fast Probabilistic Parameter Estimation for Quantitative MRI using Variational Autoencoders

  Proceedings on CD-ROM - International Society for Magnetic Resonance in Medicine. Scientific Meeting and Exhibition/Proceedings of the International Society for Magnetic Resonance in Medicine, Scientific Meeting and Exhibition · 2024-11-26

  articleSenior author

  Motivation: Mapping MRI signal into tissue parameters aims to identify robust physiologic-phenotypic associations. However, conventional methods are computationally expensive, limiting their applicability in research or clinical practice. Goal(s): To develop fast and robust techniques for estimating quantitative tissue parameters under a probabilistic framework using MRI signals. Approach: Train and evaluate the performance of variational autoencoders and compare its capabilities with state-of-the-art deep learning methods on both synthesized and real MRI data. Results: Compared to existing autoencoder-based methods, both synthetic and real data experiments show enhanced performance of VAEs on tissue parameter estimation. Parameter maps produced from real data show higher similarity to gold-standard maps. Impact: We show that variational autoencoders can be trained for fast inference of quantitative parameter estimation MRI data quantification in qMRI.

  PublisherDOI

• Report from the NSF Conference on Implicit Bias

  Cambridge University Press eBooks · 2024-12-21

  book-chapter
  PublisherDOI

• E018 Characterising the earliest neurodegenerative changes in HD: multi-modal neuroimaging insights from the Huntington’s disease young adult study (HD-YAS)

  2024-09-01

  articleOpen access

  <h3>Background</h3> HD-YAS aims to characterise the HD phenotype ~24 years from predicted disease onset in a unique cohort of gene expansion carriers (GECs), evaluated at two time-points ~4.5 years apart. <h3>Aims</h3> To characterise the earliest neurodegenerative changes with multi-modal MRI. <h3>Methods</h3> 154 participants were recruited: 131 at visit 1 (64 GECs, 67 controls) and 23 additional participants at visit 2 (9 GECs, 14 controls). &gt;90% of participants underwent 3T MRI, providing volume/atrophy, diffusion, structural-connectivity, and quantitative-MRI (multi-parameter mapping (MPMs)) metrics. These were assessed cross-sectionally over pre-defined regions-of-interest, using all datapoints and mixed effect regression with random participant effect. Longitudinal direct change analyses used linear regression of a single change measure per participant. <h3>Results</h3> Volumetrics: Cross-sectionally, GECs showed reductions in whole-brain, grey-matter, white-matter, caudate and putamen volumes compared with controls, which were associated with age, CAG, or their interaction (FDR&lt;0.15). Longitudinally, elevated atrophy rates were evident in all regions-of-interest (FDR&lt;0.02), and most prominent in the caudate and putamen (FDR&lt;1.2x10–9); rates were influenced by age, CAG or their interaction (FDR&lt;1.5x10–2). MPMs: Cross-sectionally, R1 was elevated in the putamen in GECs compared with controls (FDR=0.1); and associated with age and CAG (FDR=0.1), suggestive of increased iron levels. There was no evidence of differences in metrics sensitive to demyelination. There were no significant longitudinal findings. Structural connectivity: No significant findings. <h3>Conclusions</h3> Elevated atrophy rates, particularly striatal, are evident &gt;20 years prior to predicted symptom onset. Increased iron in the putamen may be a very early feature. Together with the absence of congruent myelin-contrast decreases, this is suggestive of increased levels of toxicity and neuronal loss.

  PublisherOA PDFDOI

• Social Listening in Gout: Impact of Proactive vs. Reactive Management on Self-Reported Emotional States

  Rheumatology and Therapy · 2024-01-22 · 3 citations

  articleOpen access

  INTRODUCTION: This study aimed to characterize patient-reported outcomes from social media conversations in the gout community. The impact of management strategy differences on the community's emotional states was explored. METHODS: We analyzed two social media sources using a variety of natural language processing techniques. We isolated conversations with a high probability of discussing disease management (score > 0.99). These conversations were stratified by management type: proactive or reactive. The polarity (positivity/negativity) of language and emotions conveyed in statements shared by community members was assessed by management type. RESULTS: Among the statements related to management, reactive management (e.g., urgent care) was mentioned in 0.5% of statements, and proactive management (e.g., primary care) was mentioned in 0.6% of statements. Reactive management statements had a significantly larger proportion of negative words (59%) than did proactive management statements (44%); "fear" occurred more frequently with reactive statements, whereas "trust" predominated in proactive statements. Allopurinol was the most common medication in proactive management statements, whereas reactive management had significantly higher counts of prednisone/steroid mentions. CONCLUSIONS: A unique aspect of examining gout-related social media conversations is the ability to better understand the intersection of clinical management and emotional impacts in the gout community. The effect of social media statements was significantly stratified by management type for gout community members, where proactive management statements were characterized by more positive language than reactive management statements. These results suggest that proactive disease management may result in more positive mental and emotional experiences in patients with gout.

  PublisherOA PDFDOI

• Status threat: The core of reactionary politics

  Political Psychology · 2024-05-13 · 19 citations

  articleOpen access1st author

  Abstract In recent years, reactionary movements have overtaken the politics of western democracies and developing countries alike. Using the United States is a case in point, we offer a theory of what motivates reactionary movements. While controlling for conventional individual‐level accounts of reactionary psychological dispositions, we offer a fresh explanation: status threat . We argue that status threat, a reaction to rapid sociocultural change on the part of dominant groups, pushes some members of these groups into joining and supporting reactionary movements and parties, respectively. We first outline the social psychology of the group (White, Christian, patriarchal, native born, heteronormative) that animates a movement (MAGA) that, in turn, has taken over a party (the GOP). We then test a wide range of hypotheses using two original data sets, finding robust evidence to support our claim: status threat is a major source of the increasing fractionalization of American society and politics, one that threatens American democracy.

  PublisherOA PDFDOI

• Foreword

  2024-12-21

  other1st authorCorresponding
  PublisherDOI

• Separate but Unequal: Ethnocentrism and Racialization Explain the “Democratic” Peace in Public Opinion

  American Political Science Review · 2024-05-27 · 12 citations

  articleOpen accessCorresponding

  Why are democratic publics reluctant to use force against fellow democracies? We hypothesize that the democratic peace in public opinion owes, in large part, to racialized assumptions about democracy. Rather than regime type per se doing the causal work, the term “democracy” inadvertently primes the presumption that target countries are predominantly white. This implicit racialization, in turn, explains the reluctance of the American public to support aggression against fellow democracies, most notably among respondents higher in ethnocentrism who disproportionately drive the democratic peace treatment effect. Two original survey experiments, a large-scale word embedding analysis of English texts, and reanalyses of published studies support this expectation. Our results suggest that the democratic peace in public opinion is, largely, an ethnocentric and racialized peace. The findings hold implications for the role of racism and racialization in foreign policy opinion research generally.

  PublisherOA PDFDOI

• Fine‐grained ordering of white matter degeneration in the Alzheimer’s disease pathophysiological cascade

  Alzheimer s & Dementia · 2023-06-01

  articleOpen access1st authorCorresponding

  Abstract Background The role of white matter (WM) neurodegeneration in Alzheimer’s disease (AD) is poorly understood. Fine‐grained sequencing of WM neurodegeneration could provide new avenues for early diagnosis and novel disease‐modifying therapies to slow or halt AD progression. Previous approaches are limited by their coarse granularity and incomplete disease coverage. In this study, we apply event‐based disease progression modelling (DPM) (Fonteijn et al, Neuroimage, 2012), which can provide fine‐grained ordering, to estimate progression of regional WM abnormality in AD. Method Diffusion tensor imaging (DTI) markers of WM abnormality and Freesurfer volumetric markers of grey matter (GM) atrophy were obtained from ADNI. DTI markers were hemisphere‐averaged and GM volumes were normalised by head size. Eleven WM ROIs with reported AD abnormality and 4 reference GM ROIs were selected for sequencing (abbreviations in Table 1), yielding complete data for 83 cognitively normal subjects, 40 AD patients and 102 MCI subjects. Event‐based DPM (github.com/ucl‐pond/kde_ebm) was used to estimate a data‐driven sequence of neurodegeneration and its uncertainty (positional variance), and individuals were assigned to their most likely stage (Young et al., Brain, 2014). Resampling analysis assessed the robustness of the estimated sequence. Result Fig. 1 shows the first data‐driven sequence of WM abnormalities in AD, including positional variance, with GM abnormality events for reference. The earliest WM events are increases in mean diffusivity (MD) in CGH and axial diffusivity (AxD) in FX and BCC. Subsequently, a cascade of AxD events in corpus callosum regions precedes abnormality in other medial temporal lobe WM structures. Fig. 2 shows the sequence is relatively robust under resampling, with low positional variance and similar median positions for most ROIs. Subject staging (Fig. 3, 4) shows that the fine‐grained approach splits MCI subjects with hippocampal atrophy into those with hippocampal atrophy and those with additional increased MD in CGH. Conclusion This study finds WM microstructural abnormality among the earliest events in AD. Early hippocampal WM abnormality and corpus callosum ordering are consistent with early memory deficits in AD and inferences from cruder group‐based comparisons. The order suggests Wallerian degeneration rather than retrogenesis is the primary driver of WM neurodegeneration in AD.

  PublisherOA PDFDOI

Frequent coauthors

• Matt A. Barreto

  15 shared

• Rachel Blum

  14 shared

• Sarah J. Tabrizi

  University College London

  12 shared

• Marina Papoutsi

  University College London

  9 shared

• Kate Fayer

  9 shared

• Rachael I. Scahill

  9 shared

• Jessica Lowe

  Malaghan Institute of Medical Research

  8 shared

• Eileanoir B. Johnson

  University College London

  8 shared

Awards & honors

• American Political Science Association's Ralph J. Bunche Awa…
• American Political Science Association's award for the best…