Human behavior in Prisoner's Dilemma experiments suppresses network reciprocity

During the last few years, much research has been devoted to strategic interactions on complex networks. In this context, the Prisoner's Dilemma has become a paradigmatic model, and it has been established that imitative evolutionary dynamics lead to very different outcomes depending on the details of the network. We here report that when one takes into account the real behavior of people observed in the experiments, both at the mean-field level and on utterly different networks the observed level of cooperation is the same. We thus show that when human subjects interact in an heterogeneous mix including cooperators, defectors and moody conditional cooperators, the structure of the population does not promote or inhibit cooperation with respect to a well mixed population.Comment: 5 Pages including 4 figures. Submitted for publicatio

Theoretical and empirical analysis of the evolution of cooperation

Kooperatives Verhalten lässt sich in vielen Bereichen menschlichen Zusammenlebens sowie im gesamten Tierreich beobachten. In evolutionären Modellen wurde gezeigt, dass Netzwerkstrukturen die Kooperation erhöhen können. Empirische Studien versuchten vergeblich diesen Mechanismus auch bei Menschen nachzuweisen. Es scheint, als würden Netzwerke nur dann die Kooperation erhöhen, wenn die Strukturen nicht statisch sind, sondern dynamisch. Das heißt, dass die Individuen die Möglichkeit haben, ihre Partner zu wechseln. Eine wichtige – aber bislang unerforschte – Eigenschaft dynamischer Netzwerke ist jedoch, dass derartige Wechsel von Partnern in der Regel Kosten verursachen, ob in Form von Zeit oder Ressourcen. Kapitel I meiner Arbeit schließt diese Lücke, in dem es sich mit den Effekten von Kosten auf dynamischen Netzwerken befasst. Ich konnte nachweisen, dass Menschen seltener Interaktionen mit Partnern beendeten, wenn die Kontaktaufnahme mit einem neuen Partner mit Kosten verbunden war. Bei sehr hohen Kosten, wurden Partner so selten gewechselt, dass das Netzwerk fast statisch war. Interessanterweise blieb die Kooperation dennoch sehr hoch. Das bedeutet, dass für kooperatives Verhalten entscheidend ist, ob man die Möglichkeit hat, Partner zu wechseln. Im Gegensatz zu bisherigen Annahmen ist es daher nicht wichtig, wie oft tatsächlich Partner gewechselt werden, sondern lediglich ob es die Möglichkeit dazu gibt. In Kapitel II beschäftige ich mich mit optimalem Entscheidungsverhalten. Im sogenannten Judge-Advisor-System geht es darum, dass eine Person, der Judge, eine unbekannte numerische Größe schätzen will. Dazu erhält der Judge eine zweite unabhängige Schätzung als Rat von einer zweiten Person, des Advisor. Schließlich ist die Frage, wie der Judge optimal den Rat verwerten kann um seine Anfangsschätzung zu verbessern. Bisherige Forschung konzentrierte sich hauptsächlich auf zwei mögliche Methoden, (i) das Bilden des Mittelwerts und (ii) das Wählen der besseren Anfangsschätzung. Das Hauptargument für diese einfachen Methoden ist deren häufige Verwendung in bisherigen Experimenten. Allerdings wurden sehr wohl auch andere Gewichtungen beobachtet und daher ist eine gründliche Analyse der optimalen Gewichtung erforderlich. In der vorliegenden Arbeit leitete ich ein normatives Modell her, das beschreibt, unter welchen Bedingungen welche Methode das bestmögliche Ergebnis liefert. Es wurden drei Methoden verglichen: (i) das Bilden des Durchschnitts, (ii) das Wählen der besseren Anfangsschätzung, und (iii) das Bilden eines gewichtetet Mittelwerts, wobei das Gewicht vom Kompetenzunterschied abhängt. Welche Methode optimal ist, hängt davon ab, wie groß der Kompetenzunterschied ist und wie gut er vom Judge erkannt wird. Die Durchschnittbildung ist immer dann vorteilhaft, wenn der Kompetenzunterschied nicht groß ist, oder nur schwer richtig eingeschätzt werden kann. Wenig überraschend lohnt sich das Wählen der besseren Anfangsschätzung, wenn der Kompetenzunterschied hinreichend groß ist, vorausgesetzt es wird tatsächlich die bessere Anfangsschätzung gewählt. Wenn der Kompetenzunterschied vom Judge gut eingeschätzt werden kann, ist eine Entsprechende Gewichtung immer die beste Methode, unabhängig vom tatsächlichen Unterschied. In Übereinstimmung mit bisheriger Forschung wurde auch die Kombination von Durchschnittbildung und Wählen der besseren Anfangsschätzung untersucht. Diese Kombinationsmethode beruht darauf, bei als gering eingeschätztem Kompetenzunterschied den Durchschnitt zu bilden und ansonsten die bessere Anfangsschätzung zu wählen. Interessanterweise schneidet diese Kombinationsmethode sehr schlecht ab, was hauptsächlich daran liegt, dass zu oft die falsche Anfangsschätzung genommen würde. Insgesamt ist das gewichtete Mittel also eine geeignete Methode für einen großen Parameterbereich

A Computational Model of Worker Protest

This paper presents an agent-based model of worker protest. Workers have varying degrees of grievance depending on the difference between their wage and the average of their neighbors. They protest with probabilities proportional to grievance, but are inhibited by the risk of being arrested – which is determined by the ratio of coercive agents to probable rebels in the local area. We explore the effect of similarity perception on the dynamics of collective behavior. If workers are surrounded by more in-group members, they are more risk-taking; if surrounded by more out-group members, more risk-averse. Individual interest and group membership jointly affect patterns of workers protest: rhythm, frequency, strength, and duration of protest outbreaks. Results indicate that when wages are more unequally distributed, the previous outburst tends to suppress the next one, protests occur more frequently, and they become more intensive and persistent. Group identification does not seriously influence the frequency of local uprisings. Both their strength and duration, however, are negatively affected by the ingroup-outgroup assessment. The overall findings are valid when workers distinguish \'us\' from \'them\' through simple binary categorization, as well as when they perceive degrees of similarity and difference from their neighbors.Workers Protest, Tags, Group Identity, Trust, Netlogo

Behaviour from an evolutionary point of view: experimental studies on fish and humans

Evolutionary theory based on natural selection states that individuals of a population vary in certain traits and pass these traits on to their offspring. Furthermore, individuals continuously compete with each other for limited resources, such as food items, mating partners, and territories. As a consequence, those individuals that feature traits enabling them to cope better with the current environmental conditions have an advantage in accessing and exploiting these resources and can, therefore, allocate more resources to reproduction. Thus, they will outcompete those individuals not having such advantageous traits and the respective traits will spread in the population. Disadvantageous traits will diminish. The result of evolution is ever better adapted organisms. However, there are many traits that do not seem to be advantageous to the individual, but they still have evolved. The present work focuses on two such phenomena that are disadvantageous and costly at the first sight: sexual reproduction and human cooperation. Sexual reproduction is disadvantageous, because only one half of the population can bear offspring. Furthermore, it is costly to the individual, because, among other things, individuals have to search for mates. It has been suggested that sexually reproducing organisms have an advantage due to a higher genetic recombination rate. Thus, they are supposed to have an increased ability to adapt to environmental changes. A potential source of such changes are parasites: Organisms potentially need to continuously develop better adapted immune defence (e.g., genes of the major histocompatibility complex, MHC) to successfully fight parasites. This exerts selection pressure on the parasites which have to adapt subsequently. The result is an arms race between host and parasites in which it would be advantageous for the host to achieve a high genetic recombination rate and, hence, a high adaptability by sexual reproduction. A crucial behaviour connected to sexual reproduction is mate choice, and the threespined stickleback is a perfectly suited model organism to investigate this behaviour in more detail. It is known that female sticklebacks base their mating decision on various visual and olfactory male cues, such as red breeding colouration (visual cue) and MHC peptides (olfactory cue). Adding on to previous work, Chapter 1 deals with seasonal variation of male olfactory attractiveness to female sticklebacks. Our results document that, besides the MHC signal, a further cue conveys information about potential mates; male olfactory attractiveness to females peaked in summer while the males maintained a nest. This finding suggests that males release special substances during nest maintenance that indicate male reproductive status to females. Evidently, female olfactory mate choice is not only based on the MHC signal, but on a combination of at least two cues. A second experiment (Chapter 2) examined the evolutionary consequences of mate choice in sticklebacks under semi-natural conditions. Thereby, the focus was on MHC-based mate choice, and actual matings were analysed in six enclosure facilities in the lake Großer Plöner See. The obtained results are consistent with previous studies that linked MHC genetics with fitness related traits, and show that individuals with an intermediate number of MHC variants ultimately achieve the highest reproductive output. Consequently, choosing the right mate bearing the best MHC genotype might confer the individual advantage needed to cope with an ever changing environment of parasites. This finding is in line with the hypothesis that parasite pressure is a potential cause of the evolution and maintenance of sexual reproduction. Another seemingly paradoxical phenomenon for evolutionary biologists is the evolution and maintenance of cooperation. Cooperation describes behaviour that is beneficial for another individual, but costly for the cooperator. Thus, a cooperator is someone who invests his own resources in order to help others. Evidently, a defector (i.e., someone who does not cooperate) does not bear the costs of cooperation and, therefore, has more resources to himself. But why is cooperative behaviour so abundant if it is costly? This is especially puzzling in the case of humans which tend to cooperate even with unrelated individuals in one-shot encounters. In general, university students played computer-based games that served as experimental setup for the research presented in the second part of this thesis. Analysing the participants’ behaviour provided further insight into the phenomenon of human cooperation. A first study (Chapter 3) has elucidated whether the evolved strategies also enable humans to solve modern social dilemmas. Thereby, we focused in Chapter 3 on a global dilemma that we characterised as a collective-risk social dilemma: the prevention of dangerous climate change. To reduce the risk of dangerous climate change, greenhouse gas emissions need to be reduced to ~50% of the present level by 2050. Thus, states, companies, but also private individuals need to invest in environmentally friendly technologies and practices. In order to reduce greenhouse gas emissions down to a certain threshold, we need to invest in climate protection up to a certain threshold. Otherwise we will face substantial human, ecological, and economic losses. This scenario was simulated in an experimental game with 30 groups of six students each. The participants’ investments in climate protection had to reach a known threshold to prevent dangerous climate change. Participants only reached this threshold if the risk of personal loss was high. Thus, we conclude that humans are able to solve the real climate dilemma if they are convinced about the extreme risk of losses. Further experiments on cooperation (Chapters 4 and 5) are based on the finding that humans tend to direct their help towards people that have previously helped others. This so called indirect reciprocity can explain high levels of cooperation and is based on the reputation of the other person. But how do people get to know the reputation of others? Evidently, we cannot observe all the people we possibly interact with during our entire life, therefore various scientists proposed gossip as a possible means of spreading and gathering this information. In this thesis, this proposed function of gossip has been investigated experimentally. The first study in this context (Chapter 4) has shown that gossip indeed can serve as a vector for social, reputation-relevant information. Participants described the observed behaviour of others truthfully; this gossip was perceived as positive or negative in accordance with the author’s intention; and, last, participants reacted on positive gossip with cooperative behaviour, and on negative gossip with defection towards the person who was described by that gossip. Yet, gossip also seems to have a strong manipulative potential; people’s decisions were influenced by gossip designed by the experimenter even if they knew hard facts (i.e., past behaviour) about the other person. In a follow-up study (Chapter 5), this effect was examined in more detail. The effect of multiple gossip statements was examined with respect to elicited cooperation from the people encountering them. The participants’ response was compared to the same people’s response based on a single gossip statement or direct observation. The results indicate that an increased number of gossip statements helps to reduce the risk of manipulation and to direct cooperative behaviour towards cooperators. Furthermore, this study suggests a strong connection between reputation, reciprocity, and trust: Participants who gained a high reputation through reciprocating were also perceived as more trustworthy. This connection might have fostered cooperative behaviour up to the present level in modern human societies. These findings support the hypothesis that gossip and, hence, the use of language, is connected to the high level of human cooperation.Summary__________________________________________________________________ 7 Zusammenfassung _________________________________________________________ 10 Introduction ______________________________________________________________ 13 Sexual reproduction ____________________________________________________________ 14 Human Cooperation ____________________________________________________________ 17 Outline __________________________________________________________________ 21 Mate choice in the three-spined stickleback __________________________________________ 21 Human cooperation_____________________________________________________________ 22 Chapter 1 Seasonal Variation of Male Attractiveness in Sticklebacks ________________ 24 Abstract______________________________________________________________________ 24 Introduction___________________________________________________________________ 25 Materials and Methods __________________________________________________________ 26 Results_______________________________________________________________________ 28 Discussion____________________________________________________________________ 30 Acknowledgements_____________________________________________________________ 31 Chapter 2 Lifetime Reproductive Success and the MHC __________________________ 32 Abstract______________________________________________________________________ 32 Introduction___________________________________________________________________ 33 Material and methods ___________________________________________________________ 34 Results_______________________________________________________________________ 37 Discussion____________________________________________________________________ 41 Acknowledgments______________________________________________________________ 43 Chapter 3 Preventing Dangerous Climate Change: a Collective-Risk Social Dilemma __ 44 Abstract______________________________________________________________________ 44 Introduction___________________________________________________________________ 45 Results and Discussion __________________________________________________________ 47 Methods______________________________________________________________________ 51 Acknowledgements_____________________________________________________________ 51 Chapter 4 Gossip as an Alternative for Direct Observation ________________________ 52 Abstract______________________________________________________________________ 52 Introduction___________________________________________________________________ 53 Results_______________________________________________________________________ 55 Discussion____________________________________________________________________ 59 Materials and Methods __________________________________________________________ 61 Acknowledgements_____________________________________________________________ 63 Chapter 5 Multiple Gossip Statements, Reputation, and Trust ______________________ 64 Abstract______________________________________________________________________ 64 Introduction___________________________________________________________________ 65 Materials and Methods __________________________________________________________ 66 Results_______________________________________________________________________ 68 Discussion____________________________________________________________________ 72 Acknowledgements_____________________________________________________________ 75 Conclusion _______________________________________________________________ 76 Acknowledgements _________________________________________________________ 78 References________________________________________________________________ 80 Appendix A ______________________________________________________________ 104 Appendix B ______________________________________________________________ 106 Appendix C ______________________________________________________________ 111 Appendix D ______________________________________________________________ 122 Appendix E ______________________________________________________________ 128 Curriculum vitae__________________________________________________________ 13

Behaviour from an evolutionary point of view: experimental studies on fish and humans

Evolutionary theory based on natural selection states that individuals of a population vary in certain traits and pass these traits on to their offspring. Furthermore, individuals continuously compete with each other for limited resources, such as food items, mating partners, and territories. As a consequence, those individuals that feature traits enabling them to cope better with the current environmental conditions have an advantage in accessing and exploiting these resources and can, therefore, allocate more resources to reproduction. Thus, they will outcompete those individuals not having such advantageous traits and the respective traits will spread in the population. Disadvantageous traits will diminish. The result of evolution is ever better adapted organisms. However, there are many traits that do not seem to be advantageous to the individual, but they still have evolved. The present work focuses on two such phenomena that are disadvantageous and costly at the first sight: sexual reproduction and human cooperation. Sexual reproduction is disadvantageous, because only one half of the population can bear offspring. Furthermore, it is costly to the individual, because, among other things, individuals have to search for mates. It has been suggested that sexually reproducing organisms have an advantage due to a higher genetic recombination rate. Thus, they are supposed to have an increased ability to adapt to environmental changes. A potential source of such changes are parasites: Organisms potentially need to continuously develop better adapted immune defence (e.g., genes of the major histocompatibility complex, MHC) to successfully fight parasites. This exerts selection pressure on the parasites which have to adapt subsequently. The result is an arms race between host and parasites in which it would be advantageous for the host to achieve a high genetic recombination rate and, hence, a high adaptability by sexual reproduction. A crucial behaviour connected to sexual reproduction is mate choice, and the threespined stickleback is a perfectly suited model organism to investigate this behaviour in more detail. It is known that female sticklebacks base their mating decision on various visual and olfactory male cues, such as red breeding colouration (visual cue) and MHC peptides (olfactory cue). Adding on to previous work, Chapter 1 deals with seasonal variation of male olfactory attractiveness to female sticklebacks. Our results document that, besides the MHC signal, a further cue conveys information about potential mates; male olfactory attractiveness to females peaked in summer while the males maintained a nest. This finding suggests that males release special substances during nest maintenance that indicate male reproductive status to females. Evidently, female olfactory mate choice is not only based on the MHC signal, but on a combination of at least two cues. A second experiment (Chapter 2) examined the evolutionary consequences of mate choice in sticklebacks under semi-natural conditions. Thereby, the focus was on MHC-based mate choice, and actual matings were analysed in six enclosure facilities in the lake Großer Plöner See. The obtained results are consistent with previous studies that linked MHC genetics with fitness related traits, and show that individuals with an intermediate number of MHC variants ultimately achieve the highest reproductive output. Consequently, choosing the right mate bearing the best MHC genotype might confer the individual advantage needed to cope with an ever changing environment of parasites. This finding is in line with the hypothesis that parasite pressure is a potential cause of the evolution and maintenance of sexual reproduction. Another seemingly paradoxical phenomenon for evolutionary biologists is the evolution and maintenance of cooperation. Cooperation describes behaviour that is beneficial for another individual, but costly for the cooperator. Thus, a cooperator is someone who invests his own resources in order to help others. Evidently, a defector (i.e., someone who does not cooperate) does not bear the costs of cooperation and, therefore, has more resources to himself. But why is cooperative behaviour so abundant if it is costly? This is especially puzzling in the case of humans which tend to cooperate even with unrelated individuals in one-shot encounters. In general, university students played computer-based games that served as experimental setup for the research presented in the second part of this thesis. Analysing the participants’ behaviour provided further insight into the phenomenon of human cooperation. A first study (Chapter 3) has elucidated whether the evolved strategies also enable humans to solve modern social dilemmas. Thereby, we focused in Chapter 3 on a global dilemma that we characterised as a collective-risk social dilemma: the prevention of dangerous climate change. To reduce the risk of dangerous climate change, greenhouse gas emissions need to be reduced to ~50% of the present level by 2050. Thus, states, companies, but also private individuals need to invest in environmentally friendly technologies and practices. In order to reduce greenhouse gas emissions down to a certain threshold, we need to invest in climate protection up to a certain threshold. Otherwise we will face substantial human, ecological, and economic losses. This scenario was simulated in an experimental game with 30 groups of six students each. The participants’ investments in climate protection had to reach a known threshold to prevent dangerous climate change. Participants only reached this threshold if the risk of personal loss was high. Thus, we conclude that humans are able to solve the real climate dilemma if they are convinced about the extreme risk of losses. Further experiments on cooperation (Chapters 4 and 5) are based on the finding that humans tend to direct their help towards people that have previously helped others. This so called indirect reciprocity can explain high levels of cooperation and is based on the reputation of the other person. But how do people get to know the reputation of others? Evidently, we cannot observe all the people we possibly interact with during our entire life, therefore various scientists proposed gossip as a possible means of spreading and gathering this information. In this thesis, this proposed function of gossip has been investigated experimentally. The first study in this context (Chapter 4) has shown that gossip indeed can serve as a vector for social, reputation-relevant information. Participants described the observed behaviour of others truthfully; this gossip was perceived as positive or negative in accordance with the author’s intention; and, last, participants reacted on positive gossip with cooperative behaviour, and on negative gossip with defection towards the person who was described by that gossip. Yet, gossip also seems to have a strong manipulative potential; people’s decisions were influenced by gossip designed by the experimenter even if they knew hard facts (i.e., past behaviour) about the other person. In a follow-up study (Chapter 5), this effect was examined in more detail. The effect of multiple gossip statements was examined with respect to elicited cooperation from the people encountering them. The participants’ response was compared to the same people’s response based on a single gossip statement or direct observation. The results indicate that an increased number of gossip statements helps to reduce the risk of manipulation and to direct cooperative behaviour towards cooperators. Furthermore, this study suggests a strong connection between reputation, reciprocity, and trust: Participants who gained a high reputation through reciprocating were also perceived as more trustworthy. This connection might have fostered cooperative behaviour up to the present level in modern human societies. These findings support the hypothesis that gossip and, hence, the use of language, is connected to the high level of human cooperation.Summary__________________________________________________________________ 7 Zusammenfassung _________________________________________________________ 10 Introduction ______________________________________________________________ 13 Sexual reproduction ____________________________________________________________ 14 Human Cooperation ____________________________________________________________ 17 Outline __________________________________________________________________ 21 Mate choice in the three-spined stickleback __________________________________________ 21 Human cooperation_____________________________________________________________ 22 Chapter 1 Seasonal Variation of Male Attractiveness in Sticklebacks ________________ 24 Abstract______________________________________________________________________ 24 Introduction___________________________________________________________________ 25 Materials and Methods __________________________________________________________ 26 Results_______________________________________________________________________ 28 Discussion____________________________________________________________________ 30 Acknowledgements_____________________________________________________________ 31 Chapter 2 Lifetime Reproductive Success and the MHC __________________________ 32 Abstract______________________________________________________________________ 32 Introduction___________________________________________________________________ 33 Material and methods ___________________________________________________________ 34 Results_______________________________________________________________________ 37 Discussion____________________________________________________________________ 41 Acknowledgments______________________________________________________________ 43 Chapter 3 Preventing Dangerous Climate Change: a Collective-Risk Social Dilemma __ 44 Abstract______________________________________________________________________ 44 Introduction___________________________________________________________________ 45 Results and Discussion __________________________________________________________ 47 Methods______________________________________________________________________ 51 Acknowledgements_____________________________________________________________ 51 Chapter 4 Gossip as an Alternative for Direct Observation ________________________ 52 Abstract______________________________________________________________________ 52 Introduction___________________________________________________________________ 53 Results_______________________________________________________________________ 55 Discussion____________________________________________________________________ 59 Materials and Methods __________________________________________________________ 61 Acknowledgements_____________________________________________________________ 63 Chapter 5 Multiple Gossip Statements, Reputation, and Trust ______________________ 64 Abstract______________________________________________________________________ 64 Introduction___________________________________________________________________ 65 Materials and Methods __________________________________________________________ 66 Results_______________________________________________________________________ 68 Discussion____________________________________________________________________ 72 Acknowledgements_____________________________________________________________ 75 Conclusion _______________________________________________________________ 76 Acknowledgements _________________________________________________________ 78 References________________________________________________________________ 80 Appendix A ______________________________________________________________ 104 Appendix B ______________________________________________________________ 106 Appendix C ______________________________________________________________ 111 Appendix D ______________________________________________________________ 122 Appendix E ______________________________________________________________ 128 Curriculum vitae__________________________________________________________ 13

Exploring Hopes And Fears From Supply Chain Innovations: An Analysis Of Antecedents And Consequences Of Supply Chain Knowledge Exchanges

This dissertation sheds light on severalhopes and fears from supply chain innovation in three distinct papers. Paper one introduces the concept of Process Innovation Propagation as an appropriation technique helping to extract the most returns out of a process innovation by exporting to supply chain partners. Paper two devises and empirically tests knowledge properties that best lead to radical and incremental supply chain innovative capabilities. Lastly, paper three conducts an exploratory study that introduces factors affecting a firm’s optimum supply chain innovation strategy. The dissertation makes a strong argument that supply chain innovation is most prominently governed by power asymmetry that may either help or hurt innovative performance

Economics of sociality

Ziel der vorliegenden Arbeit ist es, die grundlegenden Mechanismen kooperativen sowie kompetitiven Verhaltens zu erläutern. Da gerade in den letzten Jahren vermehrt versucht wurde, Ergebnisse verhaltensökonomischer Studien auch anhand evolutionsbiologischer Hypothesen über das Verhalten von Menschen zu erklären, werden in einem ersten Schritt die Grundannahmen der evolutionären Biologie und Anthropologie über das Entstehen und die Entwicklung kooperativer Verhaltensmuster aufgeführt. Da die Organisationsstruktur der Gruppe substanziellen Ein&uss auf die adaptierten sozialen und kompetitiven Verhaltensstrategien von Individuen nimmt, wird des weiteren ein besonderer Fokus auf die Evolution hierarchischer Strukturen, sowohl beim Menschen, als auch bei nicht menschlichen Primaten, gelegt. Die folgende Zusammenfassung der wichtigsten Ergebnisse verhaltensökonomischer Studien über das Entstehen und die Charakteristika sozialer Präferenzen komplettiert den Stand der Forschung und erlaubt eine kritische Evaluation der heutigen Sichtweise kooperativen Verhaltens. Hierdurch ist es möglich einige strukturelle Fehler der experimentellen Forschung, sowie mögliche Fehlinterpretationen kooperativer Verhaltensstrategien aufzudecken. Es zeigt sich, dass die interdisziplinäre Orientierung der verhaltensökonomischen Forschung über soziale Präferenzen diverse Probleme mit sich bringt. Ein kurzer Exkurs in die aktuellen Fragestellungen der Forschung zum sozio-ökonomischen Status, soll auf der einen Seite noch einmal die Wichtigkeit der sozialen Struktur als möglichen Steuerungsmechanismus sozialer Präferenzen herausstellen. Auf der anderen Seite soll hierdurch ein interdisziplinäres Forschungsprojekt, Occupational Ethology (Wallner et al., 2008 ) vorgestellt werden. Ziel dieses Projektes ist es, genau an der Schnittstelle zwischen Kooperation und Wettbewerb in der Hierarchie zu forschen und soziale Strategien und deren Folgen zu erklären.This master thesis aims at providing a more complete understanding of what are the underlying mechanisms of cooperation and competition and the behavioral transition Schritt die Grundannahmen der evolutionären Biologie und Anthropologie über das Entstehen und die Entwicklung kooperativer Verhaltensmuster aufgeführt. Da die Organisationsstruktur der Gruppe substanziellen Ein&uss auf die adaptierten sozialen und kompetitiven Verhaltensstrategien von Individuen nimmt, wird des weiteren ein besonderer Fokus auf die Evolution hierarchischer Strukturen, sowohl beim Menschen, als auch bei nicht menschlichen Primaten, gelegt. Die folgende Zusammenfassung der wichtigsten Ergebnisse verhaltensökonomischer Studien über das Entstehen und die Charakteristika sozialer Präferenzen komplettiert den Stand der Forschung und erlaubt eine kritische Evaluation der heutigen Sichtweise kooperativen Verhaltens. Hierdurch ist es möglich einige strukturelle Fehler der experimentellen Forschung, sowie mögliche Fehlinterpretationen kooperativer Verhaltensstrategien aufzudecken. Es zeigt sich, dass die interdisziplinäre Orientierung der verhaltensökonomischen Forschung über soziale Präferenzen diverse Probleme mit sich bringt. Ein kurzer Exkurs in die aktuellen Fragestellungen der Forschung zum sozio-ökonomischen Status, soll auf der einen Seite noch einmal die Wichtigkeit der sozialen Struktur als möglichen Steuerungsmechanismus sozialer Präferenzen herausstellen. Auf der anderen Seite soll hierdurch ein interdisziplinäres Forschungsprojekt, Occupational Ethology (Wallner et al., 2008 ) vorgestellt werden. Ziel dieses Projektes ist es, genau an der Schnittstelle zwischen Kooperation und Wettbewerb in der Hierarchie zu forschen und soziale Strategien und deren Folgen zu erklären

The Evolutionary dimension of Trust and its effects on cooperation

Introducción La vida social humana se sustenta en la cooperación de una forma diferente respecto a otras especies. Los científicos han indagado en la evolución de la cooperación desde distintos puntos de vista (Trivers, 1971; Dawkins, 1976; Axelrod y Hamilton, 1981; Axelrod, 1984; Caporael et al., 1989; Boyd & Richerson, 1990; Wilson & Sober, 1994; Bergstrom, 2002; Boyd et al., 2003; Gintis et al., 2003; Bowles & Gintis, 2004; Gintis et al., 2008; Boyd et al., 2010) pero ninguna de tales explicaciones dan cuenta de la complejidad de las relaciones cooperativas humanas. En este trabajo de tesis se analizan las relaciones cooperativas destacando su relación intrínseca con las relaciones de confianza. ¿Por qué cooperamos? ¿Cuál es la influencia de la confianza en la cooperación y qué papel juega la historia evolutiva en este puzle? Tomando en consideración las formas sociales adoptadas por nuestros antepasados humanos, es posible pensar en ciertos rasgos cognitivos y psicológicos específicos relevantes para entender las relaciones actuales de cooperación y, en un sentido más amplio, las relaciones sociales. El objetivo es, en definitiva, enmarcar las relaciones sociales humanas en un entorno evolutivo para explicar comportamientos sociales que existen en la actualidad. Contenido de la investigación Esta tesis trata de responder a las cuestiones planteadas anteriormente basándose primero en la relación que existe entre la evolución de la socialidad y la cognición humanas, como hipótesis de partida a contrastar en estudios posteriores. Desde esta perspectiva y, utilizando una metodología multidisciplinar procedente de disciplinas tales como la Sociología, Psicología y Antropología, se diseña un plan de investigación que trata de profundizar en mayor medida en dichos temas. El trabajo de tesis parte inicialmente de una revisión crítica sobre estudios que tratan de relacionar el comportamiento social en primates y la evolución del neocórtex –la Hipótesis del Cerebro Social de Dunbar (Dunbar, 1992; Dunbar, 1998; Dunbar & Shultz, 2007; Shultz & Dunbar, 2007; Dunbar, 2010). De dicha revisión, resulta evidente la necesidad de utilizar un enfoque más matizado para explicar la enorme complejidad de las relaciones sociales humanas. Para ello, ofrece un enorme interés el análisis de la influencia del mecanismo psicológico de la confianza. No obstante, los estudios de Dunbar, especialmente aquellos relacionados con las características propias de los grupos sociales humanos en relación a la capacidad cognitiva, son continuamente revisados a lo largo de todo este trabajo. Posteriormente se propone un marco teórico sobre los factores que influyen en la confianza (Parsons, 1970; Barber, 1983; Good, 1988; Yamagishi, 1998; Glaeser et al., 2000; Uslaner, 2002; Six, 2005; Bjørnskov, 2006; Hardin, 2006) y su posible configuración en un entorno evolutivo. Sobre esta base teórica, se diseña el posterior trabajo empírico, siempre teniendo en cuenta la hipótesis de que el ser humano tiene un comportamiento social ampliamente influenciado por un contexto de relaciones dentro de los pequeños grupos en los que ha convivido durante la mayor parte de su historia evolutiva. El marco teórico explica los elementos que conforman la confianza, la tipología y su posible configuración a lo largo de la historia evolutiva. Constituyen el substrato utilizado para llevar a término el análisis de la confianza y del comportamiento cooperativo en los siguientes trabajos empíricos. Los estudios empíricos siguen un plan basado en un diseño propio, procedente de la revisión de la literatura (Fey, 1955; Rosenberg, 1957; Wrightsman, 1964, 1974; Rotter, 1967; Survey Research Center, 1969; Christie & Geis, 1970; Johnson-George & Swap, 1982; Rempel et al., 1985; World Values Survey Association, 2009), con cuestionarios para medir el nivel de confianza general y personal en un grupo. Además se usa un juego experimental – dilema del prisionero con algunas variantes– que demuestra el comportamiento cooperativo real de los individuos. El juego se realiza en condiciones de confianza y de no confianza entre los miembros de un mismo grupo. El estudio piloto se lleva a cabo inicialmente en dos grupos diferentes. Los resultados muestran ya la influencia de las relaciones cercanas de confianza personal en la cooperación y el interés de analizar las redes de confianza (Radcliffe-Brown, 1940; Barnes, 1954; Milgram, 1967; Mitchell, 1969; Wasserman & Faust, 1994; Molina, J.L., 2001; White & Harary, 2001; Newman et al., 2003; Freeman, 2004; Eguíluz et al., 2005; Fowler & Christakis, 2010) en mayor profundidad. Los resultados de este trabajo se confirman en un estudio similar posterior con otros grupos más numerosos y más comparables entre sí. Los nuevos resultados muestran cómo la cooperación se relaciona en buena medida con un compromiso afectivo de reciprocidad que proviene de la confianza personal, como elemento adaptativo hacia una cooperación más exitosa, incluso en condiciones de anonimato y pese a la posibilidad de causar un perjuicio en el individuo a corto plazo. Además, el estudio incluye un análisis en profundidad de las redes de confianza de estos grupos para constatar la importancia que ciertas topologías de redes de confianza pueden tener en la cohesión general de un grupo. La última parte de la tesis presenta una perspectiva más antropológica con la realización de trabajo de campo en dos zonas caracterizadas por su gran diversidad étnica: el norte de Ghana y Oaxaca, en México. Estos lugares permiten estudiar cómo interaccionan los grupos y por qué mantienen sus identidades étnicas a pesar de una historia en común. Se pretende analizar si los mecanismos de la confianza personal que aparecen a nivel individual pueden trasladarse también a grupos más grandes o a sociedades. En este caso, además de la observación directa de los grupos y de la inclusión de su contexto histórico, social, económico y político, se utilizan entrevistas y redes personales de cooperación. En el trabajo de Ghana (Rattray, 1931, 1932; Syme, 1932; Tait, 1961; Hilton, 1962; Hart, 1971; Drucker-Brown, 1975, 1992; Fussy, 1979; Laari, 1987; Awedoba, 1989, 2001; Wilks, 1989; Assimeng, 1990; Kotey, 1995; Schlottner, 2000; Oppong, 2002; Tonah, 2005), se hace un recorrido por el contexto de los grupos y se explican las características de sus redes de confianza y cooperación. En este trabajo, se observa la eficacia de la diversificación étnica como medio para crear pequeños grupos más resistentes a la hora de enfrentarse a entornos difíciles. Se muestra también la adopción de formas culturales que permiten extender los mecanismos de la confianza personal en colectivos mayores. En el último trabajo se comparan los resultados anteriores con los de México (Chance, 1979; Zeithin, 1990; Campbell, 1993; Oseguera, 2004; Reina Aoyama, 2004; Barabas, 2006, 2008; Trejo Barrientos, 2006; Spores, 2008; Joyce, 2010; Nahmad Sitton, 2013), en un análisis cross-cultural para identificar posibles elementos “universales” en las redes de confianza y cooperación y también las influencias culturales. Conclusiones Mediante los anteriores trabajos se muestra que la confianza es uno de los mecanismos cognitivos y psicológicos más anclado en la historia evolutiva humana. Su origen evolutivo se observa en los resultados de esta tesis: al demostrarse la mayor influencia de la confianza personal sobre la confianza general a la hora de influir en la cooperación, la cual necesita de las relaciones cercanas y por tanto del pequeño grupo para su aparición –dadas las limitaciones cognitivas y temporales para mantener este tipo de relaciones con gran número de personas–, y su fuerte conexión con aspectos emocionales inconscientes –uno de los mecanismo más primitivos en los seres humanos. De hecho, tanto en el trabajo empírico como en el de campo, aparece la configuración de redes de confianza en torno a pequeños grupos. La confianza personal también puede extenderse a colectivos mayores. Incluso en las grandes sociedades más desarrolladas los individuos siguen creando sus pequeños grupos en todos los ámbitos de su vida. Sin embargo, en algunas sociedades, donde existen mayores dificultades de supervivencia, como las analizadas en esta tesis, se observan determinadas herramientas culturales que sirven para extender la confianza personal a un mayor número de personas: conceptos tales como grupos étnicos, clanes, linajes, familias, comunalidad, municipalidad en el caso oaxaqueño, valores internalizados, etc… son eficaces en este sentido. De este modo, la cultura provee de los mecanismos necesarios para crear fuertes lazos de cohesión basados en los elementos emocionales. La mayor cohesión y una actitud más abierta de confianza que surgen de tales herramientas culturales ayudan a enfrentarse a los entornos de forma más eficaz. Así pues, se podría predecir que a medida que los entornos resultan más difíciles, aparece una mayor diversificación de los grupos. Con la comparación de los resultados de Ghana y México, se profundiza en mayor medida en los elementos comunes en las redes de confianza y cooperación –aspectos universales–: los grupos pequeños y distintos niveles de emocionalidad implícita en los vínculos de confianza; y aquellos elementos culturales que se adecuan al contexto histórico y a la situación económica de los grupos, para crear una mayor o menor cohesión de sus miembros en función de sus necesidades. De este modo, además de identificarse en el campo diferentes indicadores para medir la confianza, también se identifican ciertas formas culturales que parecen más eficaces que otras a la hora de cohesionar los grupos, a saber, los valores y el sentimiento de identidad y pertenencia grupal, frente a la normatividad.Introducció La vida social humana es basa en la cooperació i la confiança d'una manera diferent de la d’altres espècies. Els científics han investigat la cooperació humana des de diferents punts de vista (Trivers, 1971; Dawkins, 1976; Axelrod y Hamilton, 1981; Axelrod, 1984; Caporael et al., 1989; Boyd & Richerson, 1990; Wilson & Sober, 1994; Bergstrom, 2002; Boyd et al., 2003; Gintis et al., 2003; Bowles & Gintis, 2004; Gintis et al., 2008; Boyd et al., 2010), però encara hi ha moltes preguntes sobre l'evolució de la cooperació sense explicació. Aquest treball de tesi analitza les relacions cooperatives emfasitzant la seva relació intrínseca amb les relacions de confiança. Per què cooperem? Quina és la influència de la confiança en la cooperació i el paper de la història evolutiva en aquest trencaclosques? Tenint en compte les formes socials adoptades pels avantpassats humans, és possible pensar en certs trets cognitius i psicològics específics que podrien tenir una importància clau per entendre les actuals relacions de cooperació i, en un sentit més ampli, les relacions socials. L'objectiu de la tesi és, en definitiva, emmarcar les relacions socials en un entorn evolutiu per explicar els comportaments socials que existeixen avui en dia. Contingut de la investigació Aquesta tesi tracta de respondre les preguntes anteriors, a partir de la relació entre l'evolució de la sociabilitat i la cognició humà, com hipòtesi inicial per contrastar els estudis posteriors. Des d'aquesta perspectiva i utilitzant una metodologia multidisciplinària de la Psicologia, Antropologia i Sociologia, es va dissenyar un pla de recerca que pretén aprofundir en aquest plantejament. Amb aquest objectiu en ment, el treball de tesi es basa inicialment en una revisió crítica d’estudis anteriors que intenten relacionar el comportament social dels primats i l'evolució del neocórtex –la Hipòtesi del Cervell Social de Dunbar (Dunbar, 1992; Dunbar, 1998; Dunbar & Shultz, 2007; Shultz & Dunbar, 2007; Dunbar, 2010). Aquesta revisió mostra clarament la necessitat d'un enfocament més matisat per explicar aquesta relació a causa de l'enorme complexitat de les relacions socials humanes. Per això, l’estudi de la influència del mecanisme psicològic de la confiança ofereix un interès enorme. No obstant això, els estudis de Dunbar, especialment aquells relacionats amb les característiques dels grups socials humans en relació amb la seva capacitat cognitiva, sóntinguts en compte al llarg de tot aquest treball. Després d’aquesta revisió es proposa un marc teòric sobre els factors que influeixen en la confiança (Parsons, 1970; Barber, 1983; Good, 1988; Yamagishi, 1998; Glaeser et al., 2000; Uslaner, 2002; Six, 2005; Bjørnskov, 2006; Hardin, 2006) i la seva possible configuració en un entorn evolutiu. En base a aquest marc teòric, es dissenyen els treballs empírics posteriors, sempre tenint en compte la hipòtesi que l'ésser humà té un comportament social àmpliament influenciat per un context de relacions dintre de petits grups. Aquest és el context social en que han viscut els humans durant la major part de la seva història evolutiva. El marc teòric explica els elements que conformen la confiança, la tipologia i la seva possible configuració al llarg de la història evolutiva. Constitueix el substrat utilitzat per dur a terme l’anàlisi de la confiança i del comportament cooperatiu en els següents treballs empírics. Aquests estudis empírics segueixen un pla basat en un disseny propi, a partir de la revisió de la literatura (Fey, 1955; Rosenberg, 1957; Wrightsman, 1964, 1974; Rotter, 1967; Survey Research Center, 1969; Christie & Geis, 1970; Johnson- George & Swap, 1982; Rempel et al., 1985; World Values Survey Association, 2009), amb qüestionaris per mesurar el nivell de confiança personal i general en un grup. També s'utilitza un joc experimental –el dilema del presoner amb algunes variacions– que demostra el comportament cooperatiu efectiu dels individus. El joc es realitza en condicions de confiança i sense confiança entre els membres d’un mateix grup. L'estudi pilot inicial es realitza en dos grups diferents. Els resultats ja mostren la influència de les relacions estretes de confiança personal en la cooperació i l'interès de anàlisi de xarxes de confiança (Radcliffe-Brown, 1940; Barnes, 1954; Milgram, 1967; Mitchell, 1969; Wasserman & Faust, 1994; Molina, J.L., 2001; White & Harary, 2001; Newman et al., 2003; Freeman, 2004; Eguíluz et al., 2005; Fowler & Christakis, 2010) en major profunditat. Els resultats d'aquest treball es confirmen en un similar estudi posterior amb altres grups més nombrosos i més comparables entre si. Els nous resultats mostren com la cooperació s'incrementa en gran mesura si es dóna un compromís afectiu inconscient de reciprocitat que ve de la confiança personal, com un element adaptatiu cap a una cooperació més efectiva i recíproca, fins i tot en condicions d'anonimat i malgrat la possibilitat de causar un prejudici en el curt termini. A més, l'estudi inclou una anàlisi en profunditat de les xarxes de confiança d’aquests grups per determinar la importància que poden tenir certes topologies de xarxes de confiança en la cohesió general d'un grup. En la darrera part de la tesi, s'utilitza una perspectiva més antropològica amb la realització de treballs de camp en dues àrees que es caracteritzen per la seva gran diversitat ètnica: nord de Ghana i Oaxaca, a Mèxic. Aquests llocs permeten estudiar com interactuen els grups i per què es mantenen les seves identitats ètniques malgrat una història i un territori en comú. Es pretén examinar també si els mecanismes de la confiança personal, que funcionen clarament a nivell individual, poden trobar-se també en grups grans o societats de gran escala. En aquest cas, a més de l'observació directa dels grups i la inclusió del seu context històric, social, econòmic i polític, s'utilitzen entrevistes i xarxes personals de cooperació. En el treball de Ghana (Rattray, 1931, 1932;) Syme, 1932; Tait, 1961; Hilton, 1962; Hart, 1971; Drucker-Brown, 1975, 1992; Primmirat, 1979; Laari, 1987; Awedoba, 1989, 2001; Wilks, 1989; Assimeng, 1990; Kotey, 1995; Schlottner, 2000; Oppong, 2002; Tonah, 2005), es mostra el context dels grups i s’explica les característiques de les seves xarxes de confiança i cooperació. En aquest estudi es posa de manifest l''eficàcia del fenomen de la diversificació ètnic com un mitjà per crear petits grups més resistents quan s'enfronten amb entorns difícils. També s'analitza l'adopció de formes culturals que permeten ampliar el mecanisme de la confiança personal a grups més grans. En l'últim treball de la tesi es comparen els anteriors resultats de Ghana amb els de Mèxic (Chance, 1979; Zeithin, 1990; Campbell, 1993; Oseguera, 2004; Reina Aoyama, 2004; Webmoney, 2006, 2008; Trejo Barrientos, 2006; Espores, 2008; Joyce, 2010; Nahmad Sitton, 2013), en una anàlisi intercultural per identificar possibles elements "universals" a les xarxes de confiança i cooperació i així com les influències culturals que modulen aquestes predisposicions humanes en cada cas. Conclusions Els diversos treballs en conjunt mostren que la confiança és un mecanisme cognitiu i psicològic ancorat en la història evolutiva humana, que ha jugat un paper important en l'evolució de la cooperació que caracteritza les societats humanes. El seu origen evolutiu es desprèn dels resultats d'aquesta tesi: es demostra que la confiança personal té més influència que la confiança general en la cooperació, que la confiança necessita relacions properes i, per tant, del petit grup per la seva aparició – tenint en compte les limitacions cognitives per mantenir aquestes relacions amb un gran nombre de persones– i la seva estreta connexió amb aspectes emocionals inconscients – un dels mecanismes més primitiu en humans. De fet, la configuració de les xarxes de confiança en petits grups apareixen tant als treballs empírics com als treballs de camp,. La confiança personal també es pot ampliar a col·lectius més grans. Fins i tot a les societats més desenvolupades les persones continuen creant els grups reduïts en tots els àmbits de la seva vida. No obstant això, en algunes societats, on hi ha importants dificultats de supervivència, com les analitzades en aquesta tesi, hi ha certes eines culturals que serveixen per ampliar la confiança personal a un major nombre de persones: conceptes com grups ètnics, clans, llinatges, famílies, coincidència, “comunalidad” i municipi en cas d'Oaxaca, valors interioritzats, etc. són eficaços en aquest sentit. Així, la cultura proporciona els mecanismes necessaris per a crear uns vincles forts de cohesió basats en elements emocionals. Una major cohesió i una actitud més oberta de confiança derivada de tals eines culturals ajuden a enfrontar-se als ambients més eficaçment. Així, es podria predir que quan els entorns són més difícils, es mostrarà una major diversificació dels grups. Amb la comparació dels resultats de Ghana i Mèxic, s'aprofundeix en major mesura en els elements comuns en les xarxes de confiança i cooperació –aspectes universals–: petits grups i diferents nivells d'emocionalitat implícita en els vincles de confiança; i elements culturals que s'adeqüin al context històric i la situació econòmica dels grups, per crear una més o menys cohesió dels seus integrants segons les seves necessitats. Així, a més d'identificar en el camp diferents indicadors i eines per mesurar la confiança, són també identificades certes formes culturals que semblen més eficaces que altres quan es tracta d'unir els grups, és a dir, els valors i el sentit d'identitat i grup de pertinença, davant les normes i l'autoritat.Introduction Human social life is sustained by cooperation in a different way with respect to other species. Scientists have investigated human cooperation from different points of view (Trivers, 1971; Dawkins, 1976; Axelrod y Hamilton, 1981; Axelrod, 1984; Caporael et al., 1989; Boyd & Richerson, 1990; Wilson & Sober, 1994; Bergstrom, 2002; Boyd et al., 2003; Gintis et al., 2003; Bowles & Gintis, 2004; Gintis et al., 2008; Boyd et al., 2010) but many questions about the evolution of cooperation remain open. In this dissertation the cooperative relationships are analyzed emphasizing its intrinsic link with trust relationships. Why do we cooperate? What is the influence of trust on cooperation and which role does human evolutionary history play in this puzzle? Considering the social forms our ancestors lived by, it is possible to think in certain cognitive and psychological traits that might have a key importance in order to understand the relationships of cooperation and, in a wider sense, the social relationships it made possible. The goal is, in short, framing social relationships in an evolutionary framework in order to explain the social behaviors of nowadays. Content of research This work attempts to answer these questions firstly on the basis of the relation between the evolution of human sociality and cognition, as a hypothesis to be tested in the following studies. From this perspective and using a multidisciplinary methodology including Sociology, Psychology and Anthropology, a research plan was designed in order to further examine these topics. This dissertation starts with a critical review of some previous studies that relate the social behavior in primates to the evolution of the neocortex –Dunbar’s Social Brain Hypothesis (Dunbar, 1992; Dunbar, 1998; Dunbar & Shultz, 2007; Shultz & Dunbar, 2007; Dunbar, 2010). This review shows the need for a more nuanced approach in order to explain this dependence because of the enormous complexity of human social relationships. To achieve this goal, the analysis of the psychological mechanism of trust offers a huge interest. However, Dunbar’s studies, especially those that relate human social groups to cognitive ability, are continuously in the background throughout all this work. Next, a theoretical framework is introduced to characterize trust and the factors that influenc

Braiding: the Interaction of Formal and Informal Contracting in Theory, Practice, and Doctrine

This Article studies the relationship between formal and informal con tract enforcement The theoretical literature treats the two strategies as separate phenomena. By contrast, a rich experimental literature considers whether the introduction of formal contracting and state enforcement "crowds out" the operation of informal contracting. Both literatures focus too narrowly on how formal contracts create incentives for parties to perform substantive actions, while assuming that informal enforcement depends on preexisting levels of trust. As a result, current scholarship misses the relationship between formal and informal contract mechanisms that characterizes contemporary contracting in practice. Parties respond to ?sing uncertainty by writing contracts that intertwine formal and informal mechanisms?what we call "braiding"?in a way that allows each to assess the disposition and capacity of the other to respond cooperatively and effectively to unforeseen circumstances. These parties agree on formal contracts for exchanging information about the progress and prospects of their joint activities, and it is this information sharing regime that "braids" the formal and informal elements of the contract and endogenizes trust. We argue that the low-powered enforcement associated with the formal governance structure in these braided contracts complements rather than crowds out the informal mechanisms that rely on increasing levels of trust. We examine the braiding phenomenon in a variety of contexts characterized by increasing uncertainty. In each instance, courts appear to have harnessed the braiding phenomenon by using low-powered sanctions to protect formal contractual "preliminaries." This technique allows potential collaborators to explore and develop their relations, but it does not impose mutually enforceable obligations to pursue a particular project. Despite the wisdom of temperate enforcement of braided contracts, however, courts that emphasize the contemporary duty to negotiate in good faith are often tempted to expand the legal sanction. We conclude by explaining how courts can best support the braiding strategies that are critical to the success of an integrated regime of formal and informal contracting

Essays on Discrimination and Endogenous Preferences

V první kapitole této disertace se zabývám efektem mezinárodní mobility na diskriminaci. Každý rok se miliony lidí stěhují do zahraničí za školou nebo za prací. Tento výzkum ukazuje, jak taková mezinárodní zkušenost mění preference a stereotypy týkající se jiných národností. Pro identifikaci změny využívám účast v programu Erasmus: studenti, kteří se chystají vycestovat do zahraničí jsou bráni jako kontrolní skupina pro studenty, kteří se z programu právě vrátili. Studenti se účastní ekonomického experimentu, kde se rozhodují ve Hře na důvěru (Trust Game) a ve Hře na diktátora (Triple Dictator Game), tak aby bylo možné oddělit změny ve statistické diskriminaci od změn v diskriminaci založené na preferencích. Výsledky ukazují, že zatímco studenti chystající se na program Erasmus nerozlišují ve Hře na důvěru mezi partnery ze severní a jižní Evropy, studenti, kteří se ze studia v zahraničí již vrátili, projevují méně důvěry k partnerům z jižní Evropy. Chování vůči jiným národnostem ve Hře na diktátora se s účastí v programu Erasmus nemění. Celkově výsledky naznačují, že studenti se během programu seznámí s rozdíly v kooperativním chování mezi jednotlivými regiony, a proto zahraniční zkušenost zvyšuje statistickou diskriminaci. Druhá kapitola se zaměřuje na interakce mezi různými etniky. Etnické...In the first chapter of this work, I focus on the effects of international mobility on discrimination. Every year, millions of people relocate to a foreign country for school or work. I provide evidence of how international experience shifts preferences and stereotypes related to other nationalities. I use participation in the Erasmus study abroad program to identify the effect of international experience: students who are ready to participate in the Erasmus program are chosen as a control group for students who have returned from studies abroad. Individuals make decisions in a Trust Game and in a Triple Dictator Game. Results show that while students do not differentiate between partners from Northern and Southern Europe in the Trust Game prior to an Erasmus study abroad, students who have returned from Erasmus exhibit less trust towards partners from the South. Behavior towards other nationalities in the Triple Dictator Game is not affected by the Erasmus study experience. Overall, the results suggest that participants learn about cross-country variation in cooperative behavior while abroad and therefore statistical discrimination increases with international experience. The second chapter concentrates on inter-ethnic interactions. Ethnic hostilities often spread rapidly, making it essential to...CERGEFaculty of Social SciencesFakulta sociálních vě