Breaking the Wall of Rising Polarization

Breaking the Wall of Rising Polarization

Global Call 2026 Finalist Interview: Social Sciences & Humanities

Federico Zimmerman is a Postdoctoral Fellow at Harvard University. He studies the psychological mechanisms underlying political segregation and affective polarization, combining experimental and computational methods. His work has been published in journals such as Science Advances, PNAS Nexus, and Nature Human Behavior. He holds a joint PhD from Universidad de Buenos Aires and Universidad Torcuato Di Tella, where he taught social psychology and neuroscience.

Which wall does your research or project break?  

My research breaks the wall of rising political polarization by uncovering a previously overlooked psychological driver: an attraction to extremity, called acrophily. Social science has long known that people primarily seek out others who are similar to themselves, a preference known as homophily. My work shows that alongside this preference for similar others, people are drawn to those who are more extreme. I have found evidence for this attraction to extremity across a wide range of contexts: face-to-face conversations between strangers on controversial political topics, online social media interactions, online surveys spanning multiple countries, and even people's own political attitudes tracked over decades of nationally representative survey data.

The core challenge my research addresses is that political polarization has largely been studied based on the assumption that people prefer similar others. My work reveals a more nuanced and troubling picture: an attraction to extremity, with far-reaching implications. This attraction shifts perceived social norms, it heightens outgroup animosity, and it reduces opinion diversity within groups.

By identifying attraction to extremity as a driver of polarization, distinct from and additive to homophily, my research helps explain our current political landscape, characterized by rising extremism among leaders, social media dynamics that reward extreme voices, and growing outgroup animosity, and points toward new avenues for intervention before polarization becomes entrenched.

What is the main goal of your research or project?  

My research has two main goals. The first is to identify the psychological mechanisms that drive people to prefer extreme others over moderate ones. The second is to trace how these individual-level preferences aggregate into large-scale patterns of political polarization and segregation.

The first goal establishes that attraction to extremity, rather than simple similarity, is a distinct and measurable driver of social choice: in face-to-face conversations, on social media, across multiple countries, and within people's own political attitudes over time. I designed a series of large-scale experiments and observational studies, including a face-to-face experiment with over 5,000 participants, an analysis of nearly two million Twitter users, and a four-decade analysis of American National Election Studies data, to demonstrate that this preference for extremity is robust across contexts, cultures, and measurement approaches.

The second goal connects these individual-level preferences to macro-level societal outcomes. Using agent-based computational models calibrated against real-world survey data, I show that when a preference for extreme ingroup members is added to conventional models of homophily, social networks reorganize into segregated clusters and opinion diversity within groups collapses, closely matching patterns observed in real polarization data.

Building on these findings, I am now leading a large, cross-national study with collaborators in over 40 countries to determine whether this attraction to extremity is a universal human tendency or shaped by cultural and structural context, and to identify which societal factors most strongly predict it. Preliminary results from five countries (Australia, Chile, Germany, South Africa, and the United States) already show that individuals consistently favor extreme ingroup members, suggesting this attraction extends well beyond the U.S. two-party system. This cross-national approach also allows me to explore which macro-level country indicators, such as inequality, ideological segregation, and the strength of democratic institutions, are associated with a stronger preference for extremity.

Ultimately, my goal is to move the study of polarization from a descriptive endeavor to a predictive and actionable one: by understanding why people are drawn to extremity, we can identify early warning signs of escalating division and design interventions that strengthen social cohesion before polarization becomes entrenched.

What impact does your research or project have on society?

Political polarization is one of the most pressing threats to democratic societies today, undermining trust, cooperation, and the ability of institutions to function. My research offers society a new, empirically grounded way to understand how polarization actually forms and, in doing so, opens the door to interventions that can slow or prevent it. By showing that people are attracted not only to those similar to themselves but to those who are more extreme, my work reframes a phenomenon often attributed to abstract forces such as media echo chambers or elite rhetoric, and grounds it instead in a measurable psychological preference. This shift matters practically: policymakers, platform designers, and civic organizations can only design effective interventions once they understand the actual mechanism driving division. My finding that attitude extremity precedes shifts in partisan identity provides an early warning signal that did not previously exist. Rather than waiting for people to adopt an extreme partisan identity, which is difficult to reverse, my research shows that interventions targeting specific issue attitudes, before they harden into identity, may be a more effective and timely point of intervention. This has direct relevance for organizations designing depolarization programs, deliberative democracy initiatives, and media literacy interventions. My work on social media further shows that platforms which amplify extreme, high-engagement content may be exploiting a natural human tendency toward attraction to extremity, with measurable consequences for outgroup animosity. This has implications for platform design and content moderation policy. Finally, the international scope of my multi-country project ensures these insights are not limited to a single political system. By identifying which structural and cultural conditions amplify or dampen attraction to extremity across more than 40 countries, my research aims to inform depolarization efforts calibrated to different societies. Understanding the psychological roots of polarization is a necessary first step toward building more socially cohesive, resilient democracies.

What advice would you give to young scientists or students interested in pursuing a career in research, or to your younger self starting in science?

My advice to young scientists, and to my younger self, is to follow genuine curiosity and to pursue a good question wherever it leads. I would also encourage young scientists to be creative, for example by looking for unconventional opportunities to test their ideas. Some of my most important findings came not from a traditional lab experiment, but from a large-scale, face-to-face social experiment I organized as part of TEDx events. Being resourceful and creative about how and where you collect data can open possibilities that a conventional experimental setting cannot.

I would also advise young scientists to embrace collaboration. My current line of work began when I discovered that another researcher, whom I had never met, had independently reached conclusions similar to mine. Instead of treating this as a threat, he reached out, and that connection led to a valued mentorship and a productive ongoing collaboration. Science benefits enormously when we view others working on similar questions as potential collaborators. This spirit of collaboration has only grown: my most recent paper on attitude acrophily brought together 13 co-authors spanning different disciplines including psychology, political science, sociology, and communication studies. And my ongoing cross-national project connects collaborators in more than 40 countries.