Michał Ramsza

Playing minority game

We designed and conducted an experiment to see how people play the standard minority game. The experiment was conducted at the computer lab, using a special software, with a group of 15 students. Collected informations comprise individual choices and individual wealth after each time step. The results, in particular the coordination of the agents, measured by the volatility of the system, are compared for different amount of informations available to the agents.

Multimarket Minority Game

We consider a system of heterogeneous agents playing the Minority Game on two markets. At each time step, each agent plays on one of the markets only. The agents can change the market according to some switching scheme. Various switching schemes are investigated: those that depend on the performance of the agents on each of the markets, and those that determine the actual market as a function of the number of games lost on the markets. We discuss the influence of the chosen switching scheme on the overall performance of the system of agents. In particular, we study both aggregate attendance (price returns) and volatilities for various schemes of the market choice.

Stability of pure strategy sampling equilibria

The idea of procedurally rational players was introduced in [4]. Among other procedures, the sampling procedure was proposed. The resulting equilibrium was called a sampling equilibrium. Evolutionary approach to the notion of a sampling equilibrium was developed in [7], where some instability results were proved. Using the concept of first-order stochastic dominance, we introduce the notion of a superior strategy and prove a stability result.

A Model of Distributed Markets with Heterogeneous Agents

We consider a model of heterogeneous, inductive rational agents, who interact through an aggregate, collective variable, and act on a finite system of local markets, where they play the Minority Game (MG). The markets have their local histories. Any agent at any time can play only on a single local market, but over time they may change the market according to certain rules. In this paper we focused on the differences and similarities between MG played on one single market (global market) and MG played on a system of local markets.

Imagine-Self Perspective-Taking and Rational Self-Interested Behavior in a Simple Experimental Normal-Form Game

The purpose of this study is to explore the link between imagine-self perspective-taking and rational self-interested behavior in experimental normal-form games. Drawing on the concept of sympathy developed by Adam Smith and further literature on perspective-taking in games, we hypothesize that introduction of imagine-self perspective-taking by decision-makers promotes rational self-interested behavior in a simple experimental normal-form game. In our study, we examined behavior of 404 undergraduate students in the two-person game, in which the participant can suffer a monetary loss only if she plays her Nash equilibrium strategy and the opponent plays her dominated strategy. Results suggest that the threat of suffering monetary losses effectively discourages the participants from choosing Nash equilibrium strategy. In general, players may take into account that opponents choose dominated strategies due to specific not self-interested motivations or errors. However, adopting imagine-self perspective by the participants leads to more Nash equilibrium choices, perhaps by alleviating participants’ attributions of susceptibility to errors or non-self-interested motivation to the opponents.

Market choices driven by reference groups. An evolutionary approach

The present paper tries to answer analytically how much the reference group influence can affect an actual market share of a particular brand or product. It is found that the increase of the size of a reference group and the probability of following the majority within the reference group may lead to the temporary modest prevalence of one brand. This result requires a relatively large size of a reference group and a high probability of following the majority within the reference group. If these conditions are not satisfied the effect on the market share is negligible.