Hello, I'm

Thomas Costello

I study why people believe what they believe—and whether minds can change. At Carnegie Mellon, I build AI systems that engage with misinformation through dialogue rather than deletion.

"The test of a first-rate intelligence is the ability to hold two opposed ideas in the mind at the same time, and still retain the ability to function."

F. Scott Fitzgerald

About

A psychologist interested in how beliefs form, persist, and—occasionally—change

I'm an Assistant Professor at Carnegie Mellon University, where I direct the Viewpoints Lab. My work sits at the intersection of psychology, political science, and artificial intelligence.

Before CMU, I was a postdoc at MIT Sloan with David Rand and Gordon Pennycook, and completed my PhD at Emory under the mentorship of Scott Lilienfeld.

More about me
Thomas Costello

Belief Change

What makes people update their beliefs? I study the cognitive and social mechanisms behind attitude change, conspiracy beliefs, and motivated reasoning.

AI & Persuasion

Can AI systems engage productively with misinformation? I develop and test dialogue-based interventions using large language models.

Political Psychology

The psychology of ideology, authoritarianism, and polarization—studied with an eye toward symmetry across the political spectrum.

2026

AAAS Newcomb Cleveland Prize $25,000

For the most outstanding paper published in Science

2025

APS Rising Star

Association for Psychological Science

2024

Science Magazine Cover

Volume 385 — AI and Conspiracy Beliefs