2,086 research outputs found
The emergence of hyper-altruistic behaviour in conflictual situations
Situations where people have to decide between hurting themselves or another
person are at the core of many individual and global conflicts. Yet little is
known about how people behave when facing these situations in the lab. Here we
report a large experiment in which participants could either take dollars
from another anonymous participant or give dollars to the same participant.
Depending on the treatments, participants could also exit the game without
making any decision, but paying a cost. Across different protocols and
parameter specifications, we provide evidence of three regularities: (i) when
exiting is allowed and costless, subjects tend to exit the game; (ii) females
are more likely than males to exit the game, but only when the cost is small;
(iii) when exiting is not allowed, altruistic actions are more common than
predicted by the dominant economic models. In particular, against the
predictions of every dominant economic model, about one sixth of the subjects
show hyper-altruistic tendencies, that is, they prefer giving rather than
taking . In doing so, our findings shed light on human decision-making in
conflictual situations and suggest that economic models should be revised in
order to take into account hyper-altruistic behaviour
A Model of Human Cooperation in Social Dilemmas
Social dilemmas are situations in which collective interests are at odds with
private interests: pollution, depletion of natural resources, and intergroup
conflicts, are at their core social dilemmas.
Because of their multidisciplinarity and their importance, social dilemmas
have been studied by economists, biologists, psychologists, sociologists, and
political scientists. These studies typically explain tendency to cooperation
by dividing people in proself and prosocial types, or appealing to forms of
external control or, in iterated social dilemmas, to long-term strategies.
But recent experiments have shown that cooperation is possible even in
one-shot social dilemmas without forms of external control and the rate of
cooperation typically depends on the payoffs. This makes impossible a
predictive division between proself and prosocial people and proves that people
have attitude to cooperation by nature.
The key innovation of this article is in fact to postulate that humans have
attitude to cooperation by nature and consequently they do not act a priori as
single agents, as assumed by standard economic models, but they forecast how a
social dilemma would evolve if they formed coalitions and then they act
according to their most optimistic forecast. Formalizing this idea we propose
the first predictive model of human cooperation able to organize a number of
different experimental findings that are not explained by the standard model.
We show also that the model makes satisfactorily accurate quantitative
predictions of population average behavior in one-shot social dilemmas
On the axiomatization of convex subsets of Banach spaces
We prove that any convex-like structure in the sense of Nate Brown is
affinely and isometrically isomorphic to a closed convex subset of a Banach
space. This answers an open question of Brown. As an intermediate step, we
identify Brown's algebraic axioms as equivalent to certain well-known axioms of
abstract convexity. We conclude with a new characterization of convex subsets
of Banach spaces.Comment: 8 pages, 1 figure. v3: added post-publication note on missing
reference with partly overlapping materia
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