NORTH-SOUTH CENTRE - ETH - North-South Centre North-South ...

Behavioural heterogeneity
and human cooperation
Maintaining large-scale cooperation requires incentives to
overcome cooperation dilemmas in which freeriders enjoy
public goods created by others without bearing the costs.
Literature suggests (i) that conditional cooperation and
costly punishment can stabilise cooperation, and (ii) that
group selection based on culture provides larger scope for
the evolution of these traits. However, most evidence on the
former remains a major empirical challenge when applied
in the real world. Evaluation of the latter could be improved
by measuring culture through behavioural experiments and
by estimating cultural differentiation among neighbouring
groups of small-scale societies. In this study, we employed
a variety of behavioural experiments, household questionnaires,
and community surveys to measure these behaviours
as well as other factors, and then study their effect
on the outcomes of forest commons management. The
study area covered 49 groups of the Bale Oromo people in
Ethiopia.
Our results show that high shares of conditional cooperators
in a group have a significantly positive effect on the
outcomes, even after controlling for conventional factors.
Costly monitoring is a key mechanism by which conditional
cooperators sustain cooperation. Our preliminary investigations
further show that freely conferred deference on the
group leader partially accounts for group level differences in
conditional cooperation. The investigations also show that
cultural group selection, as estimated through cultural differentiation
among 77 pairs of neighbouring small-scale
societies, provides scope for the evolution of costly cooperative
traits. A detailed examination of the punishment
behaviour of a group leader in response to deviations from
co-operation norms reveals substantial variations. Normdriven
leaders who explicitly punish deviations from the
conditional cooperation norm have a positive but insignificant
effect on the outcomes. In contrast, spiteful leaders
who punish cooperators have a significantly negative effect.
Furthermore, we investigated how behavioural heterogeneity
and beliefs interact in voluntary cooperation. We
find that most Bale Oromo conditional cooperators exhibit
‘‘altruistic’’ bias, contributing slightly more than the partner
player does. This challenges the hypothesis that imperfect
conditional cooperation causes decline in cooperation over
time. Our results reveal that behavioural heterogeneity is
a highly significant predictor of voluntary cooperation and
that beliefs have a positive effect on cooperation only when
a player is a conditional cooperator.
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Research fellow
Devesh Rustagi, ETH Zurich, Switzerland
Supervisors
Stefanie Engel, ETH Zurich, Switzerland;
Michael Kosfeld, University of Frankfurt, Germany
Capacity development
Research fellowships
Collaborators
Bruce Cambell, CIFOR, Indonesia;
Franz Gatzweiler and Günther Manske,
ZEF, University of Bonn, Germany;
Martin Neumann, GTZ Sustainable Utilization of Natural
Resources for Food Security (SUN), Oromia, Ethiopia;
Gurara Gebissa, Regional State of Oromia Forest
Enterprises Supervising Agency, Ethiopia
Duration
September 2008 – December 2009
Economic experiments used to analyse the prevalence
of social preferences in Ethiopian communities