Evolution of decisions in population games with sequentially searching individuals

In many social situations, individuals endeavor to find the single best possible partner, but are constrained to evaluate the candidates in sequence. Examples include the search for mates, economic partnerships, or any other long-term ties where the choice to interact involves two parties. Surprisingly, however, previous theoretical work on mutual choice problems focuses on finding equilibrium solutions, while ignoring the evolutionary dynamics of decisions. Empirically, this may be of high importance, as some equilibrium solutions can never be reached unless the population undergoes radical changes and a sufficient number of individuals change their decisions simultaneously. To address this question, we apply a mutual choice sequential search problem in an evolutionary game-theoretical model that allows one to find solutions that are favored by evolution. As an example, we study the influence of sequential search on the evolutionary dynamics of cooperation. For this, we focus on the classic snowdrift game and the prisoner’s dilemma game

The use of multiplayer game theory in the modeling of biological populations

The use of game theory in modeling the natural world is widespread. However, this modeling mainly involves two player games only, or "playing the field" games where an individual plays against an entire (infinite) population. Game-theoretic models are common in economics as well, but in this case the use of multiplayer games has not been neglected. This article outlines where multiplayer games have been used in evolutionary modeling and the merits and limitations of these games. Finally, we discuss why there has been so little use of multiplayer games in the biological setting and what developments might be useful

From Bounded Rationality to Behavioral Economics

The paper provides an brief overview of the “state of the art” in the theory of rational decision making since the 1950’s, and focuses specially on the evolutionary justification of rationality. It is claimed that this justification, and more generally the economic methodology inherited from the Chicago school, becomes untenable once taking into account Kauffman’s Nk model, showing that if evolution it is based on trial-and-error search process, it leads generally to sub- optimal stable solutions: the ‘as if’ justification of perfect rationality proves therefore to be a fallacious metaphor. The normative interpretation of decision-making theory is therefore questioned, and the two challenging views against this approach , Simon’s bounded rationality and Allais’ criticism to expected utility theory are discussed. On this ground it is shown that the cognitive characteristics of choice processes are becoming more and more important for explanation of economic behavior and of deviations from rationality. In particular, according to Kahneman’s Nobel Lecture, it is suggested that the distinction between two types of cognitive processes – the effortful process of deliberate reasoning on the one hand, and the automatic process of unconscious intuition on the other – can provide a different map with which to explain a broad class of deviations from pure ‘olympian’ rationality. This view requires re-establishing and revising connections between psychology and economics: an on-going challenge against the normative approach to economic methodology.Bounded Rationality, Behavioral Economics, Evolution, As If

Sequential vs. Simultaneous Schelling Models: Experimental Evidence

This paper shows the results of experiments where subjects play the Schelling's spatial proximity model (1969, 1971a). Two types of experiments are conducted; one in which choices are made sequentially, and a variation of the first where the decision-making is simultaneous. The results of the sequential experiments are identical to Schelling's prediction: subjects finish in a segregated equilibrium. Likewise, in the variant of the simultaneous decision experiment the same result is reached: segregation. Subjects’ heterogeneity generates a series of focal points in the first round. In order to locate themselves, subjects use these focal points immediately, and as a result, the segregation takes place again. Furthermore, simultaneous experiments with commuting costs allow us to conclude that introducing positive moving costs does not affect segregation.Schelling models, economic experiments, segregation

Neural Substrates of Decision-Making in Economic Games

In economic experiments decisions often differ from game-theoretic predictions. Why are people generous in one-shot ultimatum games with strangers? Is there a benefit to generosity toward strangers? Research on the neural substrates of decisions suggests that some choices are hormone-dependent. By artificially stimulating subjects with neuroactive hormones, we can identify which hormones and brain regions participate in decisionmaking, to what degree and in what direction. Can a hormone make a person generous while another stingy? In this paper, two laboratory experiments are described using the hormones oxytocin (OT) and arginine vasopressin (AVP). Concentrations of these hormones in the brain continuously change in response to external stimuli. OT enhances trust (Michael Kosfeld et al. 2005b), reduce fear from strangers (C. Sue Carter 1998), and has anti-anxiety effects (Kerstin Uvnäs-Moberg, Maria Peterson 2005). AVP enhances attachment and bonding with kin in monogamous male mammals (Jennifer N. Ferguson et al. 2002) and increases reactive aggression (C. Sue Carter 2007). Dysfunctions of OT and/or AVP reception have been associated with autism (Miranda M. Lim et al. 2005). In Chapter One I review past experiments with the ultimatum (UG) and dictator (DG) games and visit some of the major results in the literature. In Chapter Two I present the results of my laboratory experiment where I examine why people are generous in one-shot economic games with strangers. I hypothesize that oxytocin would enhance generosity in the UG. Players in the OT group were much more generous than those in the placebo—OT offers in the UG were 80% higher than offers on placebo. Enhanced generosity was not due to altruism as there was no effect on DG offers. This implies that other-regarding preferences are at play in the amount of money sent but only in a reciprocal context. The third chapter presents an experiment on punishment. I hypothesized that AVP would increase rejections and stinginess in the UG and TG. Results show that AVP affects rejections and stinginess in small groups but not in large ones. Chapter Four contains the summary of future research suggestions.Oxytocin; Vasopressin; ultimatum game; dictator game; trust game; generosity; altruism

Stochastic network formation and homophily

This is a chapter of the forthcoming Oxford Handbook on the Economics of Networks

Time preference and decision rules in a price search experiment

Structural econometric methods that assume agents have rational expectations are often criticized. Yet, little is known about the relative costs and benefits of adopting alternative empirical strategies. This paper compares three procedures for inference about a single structural parameter using data from a laboratory price search experiment. Our novel experimental design induces preferences up to the subjective rate of time preference, leaving unrestricted only this parameter and the decision rule that subjects use in solving the search task. We analyze the experimental data under the assumptions of both rational expectations and heuristic behavior, and we also draw inferences using a simple revealed preference analysis that does not require strong behavioral assumptions. We find that the revealed-preference analysis does not provide much information about the discount rate, while the two specifications with stronger behavioral assumptions provide sharper and statistically identical inferences about the population's discount rate distribution. However, substantial differences in inference appear at the individual level. We compare the individual discount-rate estimates to an external measure of forward looking behavior obtained for each subject using an instrument validated in the psychology literature. The estimates obtained under heuristic behavior are statistically significantly positively correlated with our external measure of time preference, while the estimates obtained under rational expectations and the revealed-preference estimates are not.

An Investigation Report on Auction Mechanism Design

Auctions are markets with strict regulations governing the information available to traders in the market and the possible actions they can take. Since well designed auctions achieve desirable economic outcomes, they have been widely used in solving real-world optimization problems, and in structuring stock or futures exchanges. Auctions also provide a very valuable testing-ground for economic theory, and they play an important role in computer-based control systems. Auction mechanism design aims to manipulate the rules of an auction in order to achieve specific goals. Economists traditionally use mathematical methods, mainly game theory, to analyze auctions and design new auction forms. However, due to the high complexity of auctions, the mathematical models are typically simplified to obtain results, and this makes it difficult to apply results derived from such models to market environments in the real world. As a result, researchers are turning to empirical approaches. This report aims to survey the theoretical and empirical approaches to designing auction mechanisms and trading strategies with more weights on empirical ones, and build the foundation for further research in the field

Stochastic learning in co-ordination games : a simulation approach

In the presence of externalities, consumption behaviour depends on the solution of a co-ordination problem. In our paper we suggest a learning approach to the study of co-ordination in consumption contexts where agents adjust their choices on the basis of the reinforcement (payoff) they receive during the game. The results of simulations allowed us to distinguish the roles of different aspects of learning in enabling co-ordination within a population of agents. Our main results highlight: 1. the role played by the speed of learning in determining failures of the co-ordination process; 2. the effect of forgetting past experiences on the speed of the co-ordination process; 3. the role of experimentation in bringing the process of co-ordination into an efficient equilibrium