Draft Complex Behaviour in Challenging Social Situations

2012

Game theory has been useful for understanding risk-taking and cooperative behavior. In the present study, subjects played the Hawk-Dove game with simulated and embodied (robotic) neural agents which used a neurobiologically plausible model of action selection and adaptive behaviors. Subjects had their serotonin levels temporarily altered through acute tryptophan depletion (ATD). The traditional assumption for subject data from Game-theory-ATD or human robot interaction (HRI) studies is that all participants come from the same underlying distribution or same group. We used probabilistic graphical models in order to determine potential sub-group affiliations based on the subjects’ responses while playing the Hawk-Dove game. The results from the models indicate sub-groups within a subject population exist. We find that two-group, one that tends toward cooperation and the other that tends toward aggression, best describes the effect of subject behavior in response to ATD and embodiment.

Game theoretic concepts apply whenever the actions of several agents are interdependent. These agents may be individuals, groups, firms, or any combination of these. The concepts of game theory provide a language to formulate, structure and analyze situations of interdependence between adaptive agents, out of which can emerge dynamics of conflict and cooperation. As a method of applied mathematics, game theory has been used to study a wide variety of human and animal behaviors. It was firstly developed in economics to understand a variety of economic behaviors, including behaviors of firms, markets, and consumers, but has since been used to model a myriad of phenomena, such as the interaction of nation states within international politics, crime, ecosystem dynamics, the routing of internet traffic and much more. Classical game theory describes the behavior of rational players. It attempts to mathematically capture behavior in strategic situations, in which an individual's success in making choices depends on the choices of others. 1 The limitations of this classical game theory 2 are long since know, but they are becoming more apparent as behavioral economics exposes them to real-world experiments and as we attempt to construct a more complex understanding of human motives and human interaction. The game theory of the past was focused on theory, mathematical elegance, closed form solutions, rigor and precise predictions, but in the process, it often ended up divorcing itself from the empirics of real-world socioeconomic interaction. Today developing models for the interaction between people is of critical importance within a wide variety of domains, both in the social sciences but also in management and design. Today there is a great demand for a game theory that puts empirics first; one that is grounded in real-world interaction and can accurately reflect the complexity of the many social interactions that we encounter on a daily basis and the motives of agents engaged in them. Achieving such a game theory framework will require a generalization of the existing game theory framework beyond its foundation. 3 As we move into the world of studying more complex systems there is an increasing demand for a more general conception of game theory. One that is capable of studying all forms of interaction between adaptive agents without the restrictive assumptions that are an inherent part of Classical Game Theory. In this paper, we look at the ongoing evolution of game theory, from its origins in classical game theory to more recent developments. We trace the past, present and potential future of game theory in search of an expanded formulation of game theory that would be relevant to the modeling of complex socioeconomic systems. Our primary focus here is on identifying the limitations within the existing game theory framework and how it can be expanded to accurately deal with more complex scenarios of socioeconomic interaction. At each step we try to identify and make explicit the assumptions inherent in standard game theory models and how these both enable and constrain the modeling process; how such assumptions may be revised in the light of new developments within complexity theory to better suit the modeling of interactions within complex socioeconomic systems.

2004

2012

Game theory has been useful for understanding risk-taking and cooperative behavior. In the present study, subjects played the Hawk-Dove game with simulated and embodied (robotic) neu-ral agents which used a neurobiologically plausible model of action selection and adaptive behaviors. Subjects had their serotonin levels temporarily altered through acute tryptophan depletion (ATD). The traditional assumption for subject data from Game-theory-ATD or human robot interaction (HRI) studies is that all participants come from the same underlying distribution or same group. We used probabilistic graphical models in order to determine potential subgroup affiliations based on the subjects' responses while playing the Hawk-Dove game. The results from the models indicate subgroups within a subject population exist. We find that two-group, one that tends toward cooperation and the other that tends toward aggression , best describes the effect of subject behavior in response to ATD and embodim...

2002

Satisficing, or being "good enough," is the fundamental obligation of rational decision makers. We cannot rationally choose an option, even when we do not know of anything better, unless we know it is good enough. Unfortunately, we are not often in the position of knowing that there could be no better option, and hence that the option must be good enough. A complete search through all logical possibilities is often impractical, particularly in multi-agent contexts, due to excessive computational difficulty, modeling complexity, and uncertainty. It can be equally impractical, if it is even possible, to determine the cost of the additional required search to find an option that is good enough. In a departure from the traditional notion of satisficing as a species of bounded rationality, satisficing is here redefined in terms of a notion of intrinsic rationality. Epistemic utility theory serves as the philosophical foundation of a new praxeological decision-making paradigm of satisficing equilibria that is applicable to both single-and multiple-agent scenarios. All interagent relationships are modeled by an interdependence function that explicitly accommodates both self and group interest, from which multilateral and unilateral selectability and rejectability mass functions can be derived and compared via the praxeic likelihood ratio test.

SSRN Electronic Journal, 2000

The implausibility of the extreme rationality assumptions of Nash equilibrium has been attested by numerous experimental studies with human players. In particular, the fundamental social dilemmas such as the Traveler's dilemma, the Prisoner's dilemma, and the Public Goods game demonstrate high rates of deviation from the unique Nash equilibrium, dependent on the game parameters or the environment in which the game is played. These results inspired several attempts to develop suitable solution concepts to more accurately explain human behaviour. In this line, the recently proposed notion of cooperative equilibrium, [5], [6], based on the idea that players have a natural attitude to cooperation, has shown promising results for single-shot games. In this paper, we extend this approach to iterated settings. Specifically, we define the Iterated Cooperative Equilibrium (ICE) and show it makes statistically precise predictions of population average behaviour in the aforementioned domains. Importantly, the definition of ICE does not involve any free parameters, and so it is fully predictive.

SSRN Electronic Journal, 2008

Common research on decision-making investigates non-interdependent situations, i.e., "games against nature". However, humans are social beings and many decisions are made in social settings, where they mutually influence each other, i.e., "strategic games". Mathematical game theory gives a benchmark for rational decisions in such situations. The strategic character makes psychological decision-making more complex by introducing the outcomes for others as an additional attribute of that situation; it also broadens the field for potential coordination and cooperation problems. From an evolutionary point of view, behavior in strategic situations was at a competitive edge. This paper demonstrates that even in games against nature, people sometimes decide as if they were in a strategic game; it outlines theoretical and empirical consequences of such a shift of the frame. It examines whether some irrationalities of human decision-making might be explained by such a shift in grasping the situation. It concludes that the mixed strategies in games against nature demand a high expertise and can only be found in situations where these strategies improve the effects of minimax-strategies that are used in cases of risk-aversion. 1 This paper has benefited from comments and suggestions received during presentations at the Max Planck Institute for Research on Collective Goods. I thank Arndt Bröder, who was a tremendous support for this paper. I also thank Ben Newell and Christoph Engel for very constructive suggestions, as well as Darrell Arnold and Brian Cooper for the helpful linguistic assistance.

Games and Economic Behavior, 2009

We report experimental results on a series of ten one-shot two-person 3x3 normal form games with unique equilibrium in pure strategies played by noneconomists. In contrast to previous experiments in which game theory predictions fail dramatically, a majority of actions taken coincided with the equilibrium prediction (70.2%) and were best-responses to subjects' stated beliefs (67.2%). In constant-sum games, 78% of actions taken were predicted by the equilibrium model, outperforming simple K-level reasoning models. We discuss how nontrivial game characteristics related to risk aversion, efficiency concerns and social preferences may affect the predictive value of different models in simple normal form games.

We report experimental data from a two-player, two-action unprofitable game with an unique mixed strategy equilibrium. Our design allows subjects to explicitly choose probability distributions over actions. Patterns of play differ greatly from the mixed strategy equilibrium and the maxmin strategy profiles, both when measured as subjects' choices of probability distributions, and as the resulting actions played. The Quantal Response Equilibrium (QRE) concept is a good predictor of the subjects' average choices.

Behavioral and Brain Sciences, 2003

In psychology, the picture is admittedly more complex. Since the publication of Freud's earliest metapsychological writings, and in particular his adumbration of the distinction between two principles of mental functioning, the BEHAVIORAL AND BRAIN SCIENCES (2003) 26, 139-198 Abstract: Rational choice theory enjoys unprecedented popularity and influence in the behavioral and social sciences, but it generates intractable problems when applied to socially interactive decisions. In individual decisions, instrumental rationality is defined in terms of expected utility maximization. This becomes problematic in interactive decisions, when individuals have only partial control over the outcomes, because expected utility maximization is undefined in the absence of assumptions about how the other participants will behave. Game theory therefore incorporates not only rationality but also common knowledge assumptions, enabling players to anticipate their co-players' strategies. Under these assumptions, disparate anomalies emerge. Instrumental rationality, conventionally interpreted, fails to explain intuitively obvious features of human interaction, yields predictions starkly at variance with experimental findings, and breaks down completely in certain cases. In particular, focal point selection in pure coordination games is inexplicable, though it is easily achieved in practice; the intuitively compelling payoff-dominance principle lacks rational justification; rationality in social dilemmas is self-defeating; a key solution concept for cooperative coalition games is frequently inapplicable; and rational choice in certain sequential games generates contradictions. In experiments, human players behave more cooperatively and receive higher payoffs than strict rationality would permit. Orthodox conceptions of rationality are evidently internally deficient and inadequate for explaining human interaction. Psychological game theory, based on nonstandard assumptions, is required to solve these problems, and some suggestions along these lines have already been put forward.