Evolution of cooperation by generalized reciprocity
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Updated: Aug 16, 2026

The Collective Trust Game: An Online Group Adaptation of the Trust Game Based on the HoneyComb Paradigm
Published on: October 20, 2022
Thomas Pfeiffer1, Claudia Rutte, Timothy Killingback
1Behavioural Ecology, University of Berne, Hinterkappelen, Switzerland. thomas.pfeiffer@inf.ethz.ch
Abstract:
The evolution of cooperation by direct reciprocity requires that individuals recognize their present partner and remember the outcome of their last encounter with that specific partner. Direct reciprocity thus requires advanced cognitive abilities. Here, we demonstrate that if individuals repeatedly interact within small groups with different partners in a two person Prisoner's Dilemma, cooperation can emerge and also be maintained in the absence of such cognitive capabilities. It is sufficient for an individual to base their decision of whether or not to cooperate on the outcome of their last encounter--even if it was with a different partner.
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