Social Influence and Drift in Collective Behavior

Alex Bentley 

Wednesdays@NICO Seminar, Noon, October 19 2011, Chambers Hall, Lower Level

Prof. Alex Bentley, University of Bristol, UK


Many explanations of human behavior -- even among the 'social' sciences -- start with people as isolated individuals, maximizing benefits versus costs. Panics or 'herding' events are often seen as anomalous departures from this norm. I would like to suggest that humans, whose very brains have evolved to handle social relations, are 'herding' much more often than commonly assumed. For a variety of modern phenomena, simple evolutionary models of social influence -- or even just random copying -- do remarkably well at capturing the large-scale dynamics of popular culture change. Such models offer an explanation for the often unpredictable flux of collective trends, especially in a modern society of unprecedented amount of choice and 'decision fatigue'. By then comparing to traditional societies, where both individual choice and social influence are often better informed, we can better understand how population scale data inform us about human decision-making and the dynamics of behavior change.


Alex Bentley is Professor of Anthropology and Archaeology at the University of Bristol. This Fall he is a Visiting Scholar at Northwestern University, spending time in both the Anthropology Department and NICO. In the U.K., Bentley is Deputy Director of a 5-year, interdisciplinary program to study 'Tipping Points' in environment and society (, a project that integrates work on climate change, the banking crisis, and the spread of fashions. Bentley has applied his research in projects with the British Department of Health, the Gates Foundation and commercial organizations. His new book, with Mark Earls and Michael O'Brien, is "I'll Have What She's Having: Mapping Social Behavior" (MIT Press). More information can be found at