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(We routinely do experiments and thus, these pages show the most relevant ones. Click at the end of each page to move to the next/previous one)

Humans behavioral phenotypes in dyadic games

Humans behavioral phenotypes in dyadic games

Socially relevant situations that involve strategic interactions are widespread among animals and humans alike. To study these situations, theoretical and experimental works have adopted a game-theoretical perspective, which has allowed to obtain valuable insights about human behavior. However, most of the results reported so far have been obtained from a population perspective and considered one specific conflicting situation at a time. This makes it difficult to extract conclusions about the consistency of individuals’ behavior when facing different situations, and more importantly, to define a comprehensive classification of the strategies underlying the observed behaviors. Here, we present the results of a lab-in-the-field experiment in which subjects face four different dyadic games, with the aim of establishing general behavioral rules dictating individuals’ actions.
By analyzing our data with an unsupervised clustering algorithm, we find that all the subjects conform, with a large degree of consistency, to a limited number of behavioral phenotypes (Envious, Optimist, Pessimist, and Trustful), with only a small fraction of undefined subjects. We also discuss the possible connections to existing interpretations based on a priori theoretical approaches. Our findings provide a relevant contribution to the experimental and theoretical efforts towards the identification of basic behavioral phenotypes in a wider set of contexts without aprioristic assumptions regarding the rules or strategies behind actions. From this perspective, our work contributes to a fact-based approach to the study of human behavior in strategic situations, that could be applied to simulating societies, policy-making scenario building and even for a variety of business applications.

J. Poncela-Casasnovas, M. Gutierrez-Roig, C. Gracia-Lazaro, J. Vicens, J. Gomez-Gardenes, J. Perello, Y. Moreno, J Duch, and A. Sanchez, “Humans display a reduced set of consistent behavioral phenotypes in dyadic games”, Science Advances 2, e1600451 (2016).

Heterogeneous Networks do not promote cooperation when humans play a Prisoners Dilemma

Heterogeneous Networks do not promote cooperation
when humans play a Prisoner’s Dilemma
Population Structure

It is not fully understood why we cooperate with strangers on a daily basis. In an increasingly globalized world, where interaction networks and relationships between individuals are becoming more complex, different hypotheses have been put forward to explain the foundations of human cooperation on a large scale and to account for the true motivations that are behind this phenomenon. In this context, population structure has been suggested to foster cooperation in social dilemmas, but theoretical studies of this mechanism have yielded contradictory results so far; additionally, the issue lacks a proper experimental test in large systems. We have performed the largest experiments to date with humans playing a spatial Prisoner’s Dilemma on a lattice and a scale-free network (1,229 subjects).
We observed that the level of cooperation reached in both networks is the same, comparable with the level of cooperation of smaller networks or unstructured populations. We have also found that subjects respond to the cooperation that they observe in a reciprocal manner, being more likely to cooperate if, in the previous round, many of their neighbors and themselves did so, which implies that humans do not consider neighbors’ payoffs when making their decisions in this dilemma but only their actions. Our results, which are in agreement with recent theoretical predictions based on this behavioral rule, suggest that population structure has little relevance as a cooperation promoter or inhibitor among humans.

C. Gracia-Lázaro , A. Ferrer , G. Ruíz , A. Tarancón , J. A. Cuesta , A. Sánchez, and Y. Moreno, “Heterogeneous networks do not promote cooperation when humans play a Prisoner’s Dilemma”, Proceedings of the National Academy of Sciences USA 109, 12922-12926 (2012).

Behavioral transition with age in social dilemmas: from reciprocal youth to persistent response in adulthood

Behavioral transition with age in social dilemmas:
From reciprocal youth to persistent response in adulthood

While human societies are extraordinarily cooperative in comparison with other social species, the question of why we cooperate with unrelated individuals remains open. Although much experimental studies have been performed to elucidate several questions related to the emergence and evolution of cooperation in humans, little has been done regarding how cooperativeness changes across our lifetime. This work reports results of a lab-in-the-field experiment with people of different ages in a social dilemma. We found that the average amount of cooperativeness is independent of age except for the elderly, who cooperated more, and a behavioral transition from reciprocal, but more volatile
behavior to more persistent actions towards the end of adolescence. Although all ages reacted to the cooperation received in the previous round, young teenagers mostly responded to what they saw in their neighborhood regardless of their previous actions. Decisions then became more predictable through midlife, when the act of cooperating or not was more likely to be repeated. Our results show that mechanisms such as reciprocity, which is based on reacting to previous actions, may promote cooperation in general, but its influence can be hindered by the fluctuating behavior in the case of children.

M. Gutiérrez-Roig, C. Gracia-Lázaro, J. Perelló, Y. Moreno, and A. Sánchez, “Behavioral transition with age in social dilemmas: From reciprocal youth to persistent response in adulthood”, Nature Communications 5:4362, doi:10.1038/ncomms5362 (2014).