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Discounting and Reciprocity in an Iterated Prisoner's Dilemma
D. W. Stephens,*C. M. McLinn,J. R. Stevens
The Iterated Prisoner's Dilemma (IPD) is a central
paradigm in the study of animal cooperation. According to the IPD
framework,repeated play (repetition) and reciprocity combine to
maintaina cooperative equilibrium. However, experimental studies withanimals suggest that cooperative behavior in IPDs is unstable,and some
have suggested that strong preferences for immediatebenefits (that is,
temporal discounting) might explain the fragilityof cooperative
equilibria. We studied the effects of discountingand strategic
reciprocity on cooperation in captive blue jays.Our results
demonstrate an interaction between discounting andreciprocity. Blue
jays show high stable levels of cooperationin treatments with reduced
discounting when their opponent reciprocates,but their levels of
cooperation decline in all other treatmentcombinations. This suggests
that stable cooperation requires bothreduced discounting and
reciprocity, and it offers an explanationof earlier failures to find
cooperation in controlled payoff games.
Department of Ecology, Evolution and Behavior, University of
Minnesota, 1987 Upper Buford Circle, St. Paul, MN 55108, USA.
*
To whom correspondence should be addressed. E-mail:
dws{at}forager.cbs.umn.edu
The editors suggest the following Related Resources on Science sites:
In Science Magazine
PERSPECTIVES
Michael Mesterton-Gibbons and Eldridge S. Adams (13 December 2002) Science298 (5601), 2146.
[DOI: 10.1126/science.1080051] |Summary »|Full Text »|PDF »
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