Yphtach Lelkes

Yphtach Lelkes is an associate professor at the University of Pennsylvania, with a primary appointment at the Annenberg School for Communication and a secondary appointment in political science. His research sits at the intersection of public opinion, political psychology, and political communication, with a focus on how the political information environment — spanning social media, news systems, and communication networks — shapes attitudes and behavior. A leading scholar on affective polarization, his work has redefined how scholars and the public understand political division in the United States and abroad.

Lelkes’s research has been widely cited, published in top general science and disciplinary journals, and featured in major international media. In 2022 he cofounded the Polarization Research Lab, which tracks global partisan animosity and elite rhetoric through continuous data collection, including weekly surveys on polarization, democratic norms, and political violence in the United States. He also serves as codirector of the Center for Information Networks and Democracy, which investigates how information systems influence democratic resilience. In 2023 he was a faculty fellow at Princeton University’s Center for the Study of Democratic Politics.

Lelkes’s project, “Rethinking Partisan Animosity as Strategic Identity Signaling,” challenges the prevailing view that partisan animosity reflects genuine hatred, arguing instead that out-party disdain often functions as a strategic signal of loyalty and credibility in an information-saturated, impersonal environment. Integrating insights from political science, psychology, communication, and economics, the project uses new experimental and observational data to show that partisan hostility is often a response to social and informational pressures.