Annenberg Professor of Natural Sciences, University of Pennsylvania
Joined September 2010
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Opportunity: Penn MindCORE Fellowship!
MindCORE seeks to recruit outstanding postdoctoral researchers for our Research Fellowship for Postdoctoral Scholars. Housed within the School of Arts & Sciences of the University of Pennsylvania, MindCORE is an interdisciplinary effort to understand human intelligence and behavior.
Applications due December 1, 2026.
mindcore.sas.upenn.edu/post-…
An evolutionary origin of collective decision making in humans and machines. New paper, with Guocheng Wang and Qi Su:
arxiv.org/abs/2610.05676
Human institutions and machine-learning algorithms both decide by layered, non-linear voting. Engineers train networks with back-propagation. Institutions have no engineer.
We find that rewarding individuals only when their vote is pivotal, at every layer, lets collective intelligence evolve by peer imitation alone. That reward scheme plays the role of back-propagation in ML.
This result gives a naturalistic, evolutionary account of decision making, by human institutions and machines alike.
Happy to share a paper led by Anzhi Sheng. We find that allocation policies that promote cooperation tend to concentrate benefits among the well-connected. And so structured societies must weigh collective success against inequality it generates.
nature.com/articles/s41586-0…
Social learning with complex contagion — new work by Hiroaki Chiba-Okabe.
We introduce a framework that combines payoff-based imitation with conformity or anti-conformity biases, and we study long-term behavioral outcomes in a population.
pnas.org/doi/10.1073/pnas.24…
We work to provide a systematic account of how risk preferences modulate, and even coevolve with, behavior in an uncertain social world.
Hopefully this framework will help us understand complex dynamics that arise from the interplay of strategic imitation and risk tolerances.
When individuals update their risk preferences along with their strategic behaviors, a population can oscillate between periods dominated by risk-averse cooperators and periods of risk-seeking defectors.
We extend evolutionary game theory to incorporate noise in payoff observation and variation in attitudes towards risk. Different risk preference can substantially alter long-term behavioral outcomes, such as promoting cooperation that would otherwise be dominated by defection.
The evolution of social behaviors and risk preferences in settings with uncertainty.
New work from Guocheng Wang et al, where we study behavioral evolution when payoff observations are noisy.
pnas.org/doi/10.1073/pnas.24…
