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The Collective Trust Game: An Online Group Adaptation of the Trust Game Based on the HoneyComb Paradigm

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Direct reciprocity in structured populations.

Matthijs van Veelen¹, Julián García, David G Rand

¹Program for Evolutionary Dynamics, Department of Psychology, Harvard University, Cambridge, MA 02138, USA. C.M.vanVeelen@uva.nl

Proceedings of the National Academy of Sciences of the United States of America

|June 6, 2012

Summary

This summary is machine-generated.

Direct reciprocity alone does not ensure cooperation, causing oscillations between cooperation and defection. However, combining direct reciprocity with population assortment promotes high levels of cooperation, mirroring human behavior.

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Area of Science:

Evolutionary Game Theory
Behavioral Economics
Social Evolution

Background:

Direct reciprocity and repeated games are central to understanding cooperation's evolution.
Direct reciprocity is often assumed to drive high cooperation levels.
Population structure (assortment) is another key factor in cooperation.

Purpose of the Study:

To investigate cooperation evolution in an infinite strategy space using direct reciprocity.
To analyze the synergistic interaction between direct reciprocity and assortment.
To model human interactions in fluid, yet structured populations.

Main Methods:

Exploration of an open-ended, infinite strategy space for potential mutants.
Analysis of direct reciprocity's efficacy in promoting cooperation.
Development of a theoretical framework for direct reciprocity and assortment interaction.

Main Results:

Direct reciprocity alone leads to perpetual oscillations between cooperation and defection, with defection dominating.
"Indirect invasions" destabilize equilibrium strategies in an infinite strategy space.
Combining direct reciprocity with even slight assortment significantly favors high cooperation.

Conclusions:

Direct reciprocity is insufficient for sustained cooperation without population structure.
Assortment plays a crucial role in stabilizing cooperation.
The synergy between reciprocity and assortment explains human cooperation patterns.