The behavior of boundedly rational agents in two interacting markets is investigated. A discrete-time model of coupled financial and consumer markets is described. The integrated model is then used to investigate feedback effects between the coupled markets. In particular, the influence of the financial market on product development is demonstrated. The types of traders present in the financial market is shown to have a large effect on firm behavior and product development. In a financial market where traders favour particular products the firms are shown to develop these favored products instead of more profitable ones. The effect is quite strong despite the only feedback being through a noisy stock price, and despite the fact that only a third of share traders are directly influenced by product position. (author's abstract) / Series: Working Papers SFB "Adaptive Information Systems and Modelling in Economics and Management Science"

Diese Arbeit präsentiert ein neuartiges mikroökonomisch fundiertes Arbeitsmarktmodell in einem partiellen Gleichgewichtsmodell. Als Theoriegerüst wird der Rahmen wiederholter Spiele in Verbindung mit dem modernen mikroökonomischen Konzept der Bounded Rationality gewählt. Die entscheidenden Modellbausteine sind dynamische strategische Interaktion, die Implementierung von informationsbasierenden Marktfriktionen, Lernregeln, Heterogenität und durch Heterogenität induzierte Arbeitsteilmärkte. Im empirischen Teil dieser Arbeit wird die Bedeutung von Heterogenität im Kontext des Arbeitsmarktes herausgearbeitet. Dazu werden verschiedene Zeitreihen zu offenen Stellen, Arbeitslosigkeit und Erwerbstätigkeit herangezogen. Die empirischen Gegebenheiten zeigen, dass Heterogenität am Arbeitsmarkt eine zentrale Rolle spielt und daher auch theoretisch nicht vernachlässigt werden darf. Unter Berücksichtigung der empirischen Resultate wird ein einfacher Humankapitalansatz konstruiert, der Arbeitssuchenden eine Anfangsausstattung (Qualifikation) und eine Umlernfähigkeit zuordnet. Diese beiden Elemente sind kompatibel mit dem spieltheoretischen Modellrahmen. Das Suchverhalten der Arbeitnehmer wird mithilfe einer perturbierten Reinforcement Lernregel beschrieben. Die Löhne in jedem Teilmarkt werden durch ein Bertrand ähnliches Spiel mit der Möglichkeit von Inaktivität festgelegt. Diese Lohnfestlegung inkorporiert strategische Interaktion zwischen Arbeitnehmern und -gebern. Die Integration der Lohn-- und Suchdynamik definiert ein Spiel, das unter allgemeinen Bedingungen zu einem stochastisch stabilen Zustand konvergiert. Stochastische Stabilität ist ein Nash Gleichgewichtserweiterungskonzept, das der perturbierten Dynamik Rechnung trägt. Das Gesamtmodell kann eine Reihe verschiedener bisher theoretisch nicht erklärbarer empirischer Arbeitsmarktphänomene erläutern. Diese Liste umfasst die Koexistenz von struktureller und friktioneller Arbeitslosigkeit und von offenen Stellen und Jobsuchenden über einen längeren Zeitraum, die Persistenz von Arbeitslosigkeit und den graduellen Rückgang dieser nach verschiedenen Schocks, Lohnunterschiede zwischen Wirtschaftssektoren und eine nicht degenerierte Lohnverteilung im Gleichgewicht. Aus aggregierter Sicht wird das für viele Arbeitsmarktmodelle fundamentale Random Matching in Frage gestellt. (Autorenref.)

As mentioned in the introduction, the objective of this work has been to get a more realistic understanding of economic decision making processes by adopting an interdisciplinary approach which takes into consideration at the same time economic and psychological issues. The research in particular has been focused on the psychological concept of categorization, which in the standard economic theory has received until now no attention, and on its implications for decision making. The three experimental studies conducted in this work provide empirical evidence that individuals don not behave according to the perfect rationality and maximization assumptions which underly the SEUT, but rather as bounded rational satisfiers who try to simplify the decision problems they face through the process of categorization. The results of the first experimental study, on bilateral integrative negotiation, show that most of the people categorize a continuum of outcomes in two categories (satisfying/not satisfying), and treat all the options within each category as equivalent. This process of categorization leads the negotiators to make suboptimal agreements and to what I call the ?Zone of Agreement Bias? (ZAB). The experimental study on committees? decision making with logrolling provides evidence of how the categorization of outcomes in satisfying/not satisfying can affect the process of coalition formation in multi-issue decisions. In the first experiment, involving 3-issues and 3-parties decisions under majority rule, the categorization of outcomes leads most of the individuals to form suboptimal coalitions and make Pareto-dominated agreements. The second experiment, aimed at comparing the suboptimizing effect of categorization under majority and unanimity rule, shows that the unanimity rule can lead to a much higher rate of optimal agreements than the majority rule. The third experiment, involving 4-issues and 4-parties decisions provides evidence that the results of experiments 1 and 2 hold even when the level of complexity of the decision problem increases.

As mentioned in the introduction, the objective of this work has been to get a more realistic understanding of economic decision making processes by adopting an interdisciplinary approach which takes into consideration at the same time economic and psychological issues. The research in particular has been focused on the psychological concept of categorization, which in the standard economic theory has received until now no attention, and on its implications for decision making. The three experimental studies conducted in this work provide empirical evidence that individuals don not behave according to the perfect rationality and maximization assumptions which underly the SEUT, but rather as bounded rational satisfiers who try to simplify the decision problems they face through the process of categorization. The results of the first experimental study, on bilateral integrative negotiation, show that most of the people categorize a continuum of outcomes in two categories (satisfying/not satisfying), and treat all the options within each category as equivalent. This process of categorization leads the negotiators to make suboptimal agreements and to what I call the ?Zone of Agreement Bias? (ZAB). The experimental study on committees? decision making with logrolling provides evidence of how the categorization of outcomes in satisfying/not satisfying can affect the process of coalition formation in multi-issue decisions. In the first experiment, involving 3-issues and 3-parties decisions under majority rule, the categorization of outcomes leads most of the individuals to form suboptimal coalitions and make Pareto-dominated agreements. The second experiment, aimed at comparing the suboptimizing effect of categorization under majority and unanimity rule, shows that the unanimity rule can lead to a much higher rate of optimal agreements than the majority rule. The third experiment, involving 4-issues and 4-parties decisions provides evidence that the results of experiments 1 and 2 hold even when the level of complexity of the decision problem increases.