Agent_Zero: Toward Neurocognitive Foundations for Generative Social Science

by Joshua M. Epstein

Overview

The Final Volume of the Groundbreaking Trilogy on Agent-Based Modeling

In this pioneering synthesis, Joshua Epstein introduces a new theoretical entity: Agent_Zero. This software individual, or "agent," is endowed with distinct emotional/affective, cognitive/deliberative, and social modules. Grounded in contemporary neuroscience, these internal components interact to generate observed, often far-from-rational, individual behavior. When multiple agents of this new type move and interact spatially, they collectively generate an astonishing range of dynamics spanning the fields of social conflict, psychology, public health, law, network science, and economics.

Epstein weaves a computational tapestry with threads from Plato, Hume, Darwin, Pavlov, Smith, Tolstoy, Marx, James, and Dostoevsky, among others. This transformative synthesis of social philosophy, cognitive neuroscience, and agent-based modeling will fascinate scholars and students of every stripe. Epstein's computer programs are provided in the book or on its Princeton University Press website, along with movies of his "computational parables."

Agent_Zero is a signal departure in what it includes (e.g., a new synthesis of neurally grounded internal modules), what it eschews (e.g., standard behavioral imitation), the phenomena it generates (from genocide to financial panic), and the modeling arsenal it offers the scientific community.

For generative social science, Agent_Zero presents a groundbreaking vision and the tools to realize it.

Product Details

ISBN-13:	9780691158884
Publisher:	Princeton University Press
Publication date:	02/23/2014
Series:	Princeton Studies in Complexity , #25
Pages:	272
Product dimensions:	6.40(w) x 9.30(h) x 1.00(d)

About the Author

Joshua M. Epstein directs the Center for Advanced Modeling at The Johns Hopkins University, where he is a professor in the Department of Emergency Medicine with joint appointments in the Departments of Applied Mathematics, Economics, International Health, Environmental Health Sciences, Biostatistics, Civil Engineering, and the Institute for Computational Medicine. He is also an external professor at the Santa Fe Institute. This volume forms a trilogy on agent-based modeling, with Growing Artificial Societies: Social Science from the Bottom Up (MIT), with coauthor Robert Axtell, and Generative Social Science: Studies in Agent-Based Computational Modeling (Princeton).

Table of Contents

Foreword xi
Preface xiii
Acknowledgments xv
INTRODUCTION 1
MOTIVATION 1
Generate Social Dynamics 2
A Core Target 2
THE MODEL COMPONENTS 5
Model Overview 6
Skeletal Equation 8
Specific Components 9
ORGANIZATION 10
Part I: Mathematical Model 10
Part II: Agent-Based Model 11
Part III: Extensions 13
Replicability and Research Resources on the Princeton University Press Website 16
Part IV: Future Research and Conclusions 17
PART 1. MATHEMATICAL MODEL 19
I.1. THE PASSIONS: FEAR CONDITIONING 19
Fear Circuitry and the Perils of Fitness 20
Nomenclature of Conditioning 29
The Rescorla-Wagner Model 33
Social Examples 37
Fear Extinction 41
I.2. REASON: THE COGNITIVE COMPONENT 46
I.3. THE SOCIAL COMPONENT 51
Simple Version of the Core Target 55
Examples of Fear Contagion 57
Mechanisms of Fear Contagion 59
Conformist Empirical Estimates 63
Generalizing Rescorla-Wagner 67
The Central Case 69
Tolstoy: The First Agent Modeler 71
A Mathematical Aside on Social Norms as Vector Fields 74
Extinction of Majorities 78
I.4. INTERIM CONCLUSIONS 80
PART II. AGENT-BASED COMPUTATIONAL MODEL 81
Affective Component 84
"Rational" Component 85
Social Component 88
Action 89
Pseudocode 89
II.1. COMPUTATIONAL PARABLES 90
Parable 1: The Slaughter of Innocents through Dispositional Contagion 90
Parable 2: Agent_Zero Initiates: Leadership as Susceptibility to Dispositional Contagion 94
Run 3. Information Cuts Both Ways 96
Run 4. A Day in the Life of Agent_Zero: How Affect and Probability Can Change on Different Time Scales 98
Run 5. Lesion Studies 102
PART III. EXTENSIONS 107
III.1. ENDOGENOUS DESTRUCTIVE RADIUS 107
III.2. AGE AND IMPULSE CONTROL 109
III.3. FIGHT VS. FLIGHT 110
Case 1: Fight 111
Case 2: Flight 112
Capital Flight 114
III.4. REPLICATING THE Latané-DARLEY EXPERIMENT 114
Threshold Imputation 115
The Dialogue 118
III.5. MEMORY 118
III.6. COUPLINGS: ENTANGLEMENT OF PASSION AND REASON 122
Mathematical Treatment 124
III.7.ENDOGENOUS DYNAMICS OF CONNECTION STRENGTH 128
Affective Homophily 128
General Setup 130
Agent-Based Model: Nonequlibrium Dynamics 135
III.8. GROWING THE 2011 ARAB SPRING 138
III.9. JURY PROCESSES 143
Phase 1. Public Phase 143
Phase 2. Courtroom Trial Phase 145
Phase 3. Jury Phase 147
III.10. EMERGENT DYNAMICS OF NETWORK STRUCTURE 152
Network Structure Dynamics as a Poincaré Map 153
Relation to Literature 159
III.11. MULTIPLE SOCIAL LEVELS 160
Agent_Zero as Witness to History 161
III.12. THE 18TH BRUMAIRE OF AGENT_ZERO 165
III.13. INTRODUCTION OF PRICES AND SEASONAL ECONOMIC CYCLES 168
Prices 168
A Christmas Story 173
III.14. SPIRALS OF MUTUAL ESCALATION 176
PART IV. FUTURE RESEARCH AND CONCLUSION 181
IV.1. FUTURE RESEARCH 181
IV.2. CONCLUSION 187
Civil Violence 187
Economics 188
Health Behavior 189
Psychology 190
Jury Dynamics 191
The Formation and Dynamics of Networks 191
Mutual Escalation Dynamics 192
Birth and Intergenerational Transmission 192
IV.3. TOWARD NEW GENERATIVE FOUNDATIONS 192
Appendix I. Threshold Imputation Bounds 195
Appendix II. Mathematica Code 197
Appendix III. Agent_Zero NetLogo Source Code 213
Appendix IV. Parameter Settings for Model Runs 221
References 227
Index 243

What People are Saying About This

From the Publisher

"Agent Zero offers a solution to some of social science's great puzzles. Its behavioral basis is the interplay of emotion, cognition, and network contagion effects. It elegantly explains why so many human actions are so manifestly dysfunctional, and why some are downright evil."—George Akerlof, Nobel Laureate in Economics

"Rarely has a book stimulated me intellectually as much as this one. Particularly exciting is the incorporation of agents who feel (affect) and deliberate, as well as influence one another through social interaction. Epstein is a brilliantly creative scholar and the range of applications showcased here is stunning. In sum, this is a pathbreaking book."—Paul Slovic, University of Oregon

"Joshua Epstein proposes a parsimonious but powerful model of individual behavior that can generate an extraordinary range of group behaviors, including mob violence, manias and financial panics, rebellions, network dynamics, and a host of other complex social phenomena. This is a highly original, beautifully conceived, and important book."—Peyton Young, University of Oxford

"In social science generally and most notably in economics, the rational actor model has long been the benchmark for policy analysis and institutional design. Epstein now offers a worthy alternative: Agent_Zero, a mathematically and computationally tractable agent whose inner workings are grounded in neuroscience. Much like you and me, Agent_Zero is influenced by emotion, reason, and social pressures. Epstein demonstrates that collections of Agent Zeros perform amazingly like real groups, teams, and societies and can therefore serve as the fundamental building blocks for what he calls Generative Social Science. The rational actor now has a true competitor. Agent_Zero is a major advance."—Scott Page, University of Michigan

"This is social science based on how our brains actually work. Epstein's computerized 'agents' can feel passion and fear, and can influence each other emotionally. And when they interact, we see many of the realities of social life, from the dynamics of juries to racist violence to Arab springs. A remarkable and original piece of work."—W. Brian Arthur, Santa Fe Institute

Editorial Reviews

"Joshua Epstein proposes a parsimonious but powerful model of individual behavior that can generate an extraordinary range of group behaviors, including mob violence, manias and financial panics, rebellions, network dynamics, and a host of other complex social phenomena. This is a highly original, beautifully conceived, and important book."—Peyton Young, University of Oxford

"This is social science based on how our brains actually work. Epstein's computerized 'agents' can feel passion and fear, and can influence each other emotionally. And when they interact, we see many of the realities of social life, from the dynamics of juries to racist violence to Arab springs. A remarkable and original piece of work."—W. Brian Arthur, Santa Fe Institute

"In social science generally and most notably in economics, the rational actor model has long been the benchmark for policy analysis and institutional design. Epstein now offers a worthy alternative: Agent_Zero, a mathematically and computationally tractable agent whose inner workings are grounded in neuroscience. Much like you and me, Agent_Zero is influenced by emotion, reason, and social pressures. Epstein demonstrates that collections of Agent Zeros perform amazingly like real groups, teams, and societies and can therefore serve as the fundamental building blocks for what he calls Generative Social Science. The rational actor now has a true competitor. Agent_Zero is a major advance."—Scott Page, University of Michigan

From the Publisher