Francesca Giardini - Academia.edu (original) (raw)
Papers by Francesca Giardini
Social Network Analysis and Mining
Gossip is a pervasive phenomenon in organizations causing many individuals to have second-hand in... more Gossip is a pervasive phenomenon in organizations causing many individuals to have second-hand information about their colleagues. However, whether it is used to inform friendship choices (i.e., friendship creation, friendship maintenance, friendship discontinuation) is not that evident. This paper articulates and empirically tests a complex contagion model to explain how gossip, through its reputational effects, can affect the evolution of friendship ties. We argue that hearing gossip from more than a single sender (and about several targets) impacts receivers’ friendships with the gossip targets. Hypotheses are tested in a two-wave sociometric panel study among 148 employees in a Dutch childcare organization. Stochastic actor-oriented models reveal positive gossip favors receiver-target friendships, whereas negative gossip inhibits them. We also find evidence supporting that, for damaging relationships, negative gossip needs to originate in more than a single sender. Positive goss...
In this work, we propose an evolutionary account of reactions to a wrong as an integrated set. Un... more In this work, we propose an evolutionary account of reactions to a wrong as an integrated set. Unlike other theories, we are not interested in revenge, punishment or sanction per se, but in their coexistence. We posit that this variety of reactions is needed in order to achieve different goals, but it also implies an increase in cognitive costs that requires to be explained from an evolutionary perspective. Moving from the identification of the psychological traits that uniquely define each reaction, two concurrent hypotheses are suggested and discussed: either the richness of human social life requests a variety of reactions, or the benefits of single reactions at the psychological level allowed these reactions to be maintained in the social life.
People use sanctioning behaviours differently according to what they believe and want to achieve,... more People use sanctioning behaviours differently according to what they believe and want to achieve, according to the context and to the situation. We need to understand the motivations for different forms of punishment in order to explain why sanctions and incentives have different effects on human behaviour. Aim of this work is to propose a cognitive model of three distinct kinds of punishing behaviours, differentiated in terms of the defining cognitive patterns.
The study of opinions, their formation and change, is one of the defining topics addressed by soc... more The study of opinions, their formation and change, is one of the defining topics addressed by social psychology, but in recent years other disciplines, as computer science and complexity, have addressed this challenge. Despite the flourishing of different models and theories in both fields, several key questions still remain unanswered. The aim of this paper is to challenge the current theories on opinion by putting forward a cognitively grounded model where opinions are described as specific mental representations whose main properties are put forward. A comparison with reputation will be also presented.
The Oxford Handbook of Gossip and Reputation, 2019
This introductory chapter sketches the contours of an emerging multidisciplinary and in terdiscip... more This introductory chapter sketches the contours of an emerging multidisciplinary and in terdisciplinary research program on the conceptual foundations, antecedents, dynamics, and consequences of gossip and reputation. It argues that this research agenda should be developed along three interrelated dimensions. First, gossip and reputation are multifac eted theoretical constructs that share at least six key characteristics. Both are relational and triadic, morally laden, multifunctional, and context-dependent social phenomena that have an evolutionary base and are subject to strategic behavior. Each of the chapters in this Handbook touches upon at least one of these facets. Second, in order to adequately capture this complexity, a multidisciplinary and eventually interdisciplinary approach is needed. Intradisciplinary progress is a precondition for high-quality multidisciplinary scholarship. Third, the frontier of much current research crystallizes around six substan tive problem domains, capturing different levels of analysis and their interplay.
Microeconomics: Welfare Economics & Collective Decision-Making eJournal, 2016
Reputation plays a major role in human societies, and it has been proposed as an explanation for ... more Reputation plays a major role in human societies, and it has been proposed as an explanation for the evolution of cooperation. While the majority of previous studies equates reputation with a transparent and complete history of players' past decisions, in real life, reputations are often ambiguous and opaque. Using web-based experiments, we explore the extent to which opaque reputation works in isolating defectors, with and without partner selection opportunities. Our results show that low reputation works as a signal of untrustworthiness, whereas medium or high reputation are not taken into account by participants for orienting their choices. We also find that reputation without partner selection does not promote cooperative behavior; that is, defectors do not turn into cooperators only for the sake of getting a positive reputation. Finally, in a third study, we find that, when reputation is pivotal to selection, then a substantial proportion of would-be defectors turn into coo...
Scientific Reports, 2016
Cooperation can be supported by indirect reciprocity via reputation. Thanks to gossip, reputation... more Cooperation can be supported by indirect reciprocity via reputation. Thanks to gossip, reputations are built and circulated and humans can identify defectors and ostracise them. However, the evolutionary stability of gossip is allegedly undermined by the fact that it is more error-prone that direct observation, whereas ostracism could be ineffective if the partner selection mechanism is not robust. The aim of this work is to investigate the conditions under which the combination of gossip and ostracism might support cooperation in groups of different sizes. We are also interested in exploring the extent to which errors in transmission might undermine the reliability of gossip as a mechanism for identifying defectors. Our results show that a large quantity of gossip is necessary to support cooperation, and that group structure can mitigate the effects of errors in transmission.
Reputation is one of the most effective solutions to the so-called «puzzle of cooperation», but i... more Reputation is one of the most effective solutions to the so-called «puzzle of cooperation», but it is usually studied in contexts in which information is not ambiguous and there are no incentives towards strategically using it. In this study, we test wheter the possibility of being evaluated (with a like or a dislike) when giving suggestions about a deal in a competitive game has an effect on truthfulness of suggestions. We designed a computer-mediated experiment and we tested adolescents in a high-school in Italy, with the aim of understanding the development of reputational dynamics and how adolescents deal with competing incentives. Our results show that when reputations introduced, adolescents become more cooperative, both in terms of donations to partners and of suggestions offered. We also observe that reputations, both positive and negative, behave as attractors, thus those of ill-repute receive negative reviews even when they cooperate, and individuals with positive reputati...
Journal of Artificial Societies and Social Simulation, 2021
The behavior of a heterogeneous population of individuals during an emergency, such as epidemics,... more The behavior of a heterogeneous population of individuals during an emergency, such as epidemics, natural disasters, terrorist attacks, is dynamic, emergent and complex. In this situation, reducing uncertainty about the event is crucial in order to identify and pursue the best possible course of action. People depend on experts, government sources, the media and fellow community members as potentially valid sources of information to reduce uncertainty, but their messages can be ambiguous, misleading or contradictory. E ective risk prevention depends on the way in which the population receives, elaborates and spread the message, and together these elements result in a collective perception of risk. The interaction between individuals' attitudes toward risk and institutions, the more or less alarmist way in which the information is reported and the role of the media can lead to risk perception that di ers from the original message, as well as to contrasting opinions about risk within the same population. The aim of this study is to bridge a model of opinion dynamics with the issue of uncertainty and trust in the sources, in order to understand the determinants of collective risk assessment. Our results show that alarming information spreads more easily than reassuring one, and that the media plays a key role in this. Concerning the role of internal variables, our simulation results show that risk sensitiveness has more influence on the final opinion than trust towards the institutional message. Furthermore, the role of di erent network structures seems to be negligible, even on two empirically calibrated network topologies, thus suggesting that knowing beforehand how much the public trusts their institutional representatives and how reactive they are to a certain risk might provide useful indications to design more e ective communication strategies during crises.
Frontiers in Psychology, 2019
Most of the current literature on gossip describes gossipmongers as incessantly sharing evaluativ... more Most of the current literature on gossip describes gossipmongers as incessantly sharing evaluative and valuable information about an absent third party in teams, groups, communities, and organizations. However, potential gossipers can similarly decide not to share what they know, depending on the content, the context, or their relationship with the other actors in the gossip triad. We argue that understanding the reasons why people do not gossip may provide useful insights into individual motives, group dynamics, and collective behaviors. This theoretical contribution first critically surveys the existing gossip literature with the aim of highlighting the conditions under which people might refrain from sharing third party information. We then propose to apply Goal Framing theory as a way to bridge a theory of the micro-foundations of human behavior with an analytical model of the gossip triad that disentangles the various ways through which senders, receivers, and objects of gossip may be interrelated. From a goal framing perspective, most research on gossip illustrates the mechanisms in which the hedonic gratification derived from gossiping is reinforced by gain or normative goals. However, a normative or a gain goal frame can prevent the gossip monger from spreading the information, and we argue that depending on different configurations of frames and relations between actors the perceived costs of sending gossip may be far higher than much of the previous literature suggests.
Scientific Reports, 2016
Cooperation can be supported by indirect reciprocity via reputation. Thanks to gossip, reputation... more Cooperation can be supported by indirect reciprocity via reputation. Thanks to gossip, reputations are built and circulated and humans can identify defectors and ostracise them. However, the evolutionary stability of gossip is allegedly undermined by the fact that it is more error-prone that direct observation, whereas ostracism could be ineffective if the partner selection mechanism is not robust. The aim of this work is to investigate the conditions under which the combination of gossip and ostracism might support cooperation in groups of different sizes. We are also interested in exploring the extent to which errors in transmission might undermine the reliability of gossip as a mechanism for identifying defectors. Our results show that a large quantity of gossip is necessary to support cooperation, and that group structure can mitigate the effects of errors in transmission.
Frontiers in Physics, 2015
The study of opinions-e.g., their formation and change, and their effects on our society-by means... more The study of opinions-e.g., their formation and change, and their effects on our society-by means of theoretical and numerical models has been one of the main goals of sociophysics until now, but it is one of the defining topics addressed by social psychology and complexity science. Despite the flourishing of different models and theories, several key questions still remain unanswered. The aim of this paper is to provide a cognitively grounded computational model of opinions in which they are described as mental representations and defined in terms of distinctive mental features. We also define how these representations change dynamically through different processes, describing the interplay between mental and social dynamics of opinions. We present two versions of the model, one with discrete opinions (voter model-like), and one with continuous ones (Deffuant-like). By means of numerical simulations, we compare the behavior of our cognitive model with the classical sociophysical models, and we identify interesting differences in the dynamics of consensus for each of the models considered.
In this work, we propose an evolutionary account of reactions to a wrong as an integrated set. Un... more In this work, we propose an evolutionary account of reactions to a wrong as an integrated set. Unlike other theories, we are not interested in revenge, punishment or sanction per se, but in their coexistence. We posit that this variety of reactions is needed in order to achieve different goals, but it also implies an increase in cognitive costs that requires to be explained from an evolutionary perspective. Moving from the identification of the psychological traits that uniquely define each reaction, two concurrent hypotheses are suggested and discussed: either the richness of human social life requests a variety of reactions, or the benefits of single reactions at the psychological level allowed these reactions to be maintained in the social life.
Lecture Notes in Computer Science, 2015
In an environment in which free-riders are better off than cooperators, social control is require... more In an environment in which free-riders are better off than cooperators, social control is required to foster and maintain cooperation. There are two main paths through which social control can be applied: punishment and reputation. Using a Public Goods Game, we show that gossip, used for assortment under three different strategies, can be effective in large groups, whereas its efficacy is reduced in small groups, with no main effect of the gossiping strategy. We also test four different combinations of gossip and costly punishment, showing that a combination of punishment and reputation-based partner selection leads to higher cooperation rates.
Advances in Intelligent Systems and Computing, 2014
In an environment in which free-riders are better off than cooperators, social control is require... more In an environment in which free-riders are better off than cooperators, social control is required to foster and maintain cooperation. There are two main paths through which social control can be applied: punishment and reputation. Our experiments explore the efficacy of punishment and reputation on cooperation rates, both in isolation and in combination. Using a Public Goods Game, we are interested in assessing how cooperation rates change when agents can play one of two different reactive strategies, i.e., they can pay a cost in order to reduce the payoff of free-riders, or they can know others' reputation and then either play defect with free-riders, or refuse to interact with them. Cooperation is maintained at a high level through punishment, but also reputation-based partner selection proves effective in maintaining cooperation. However, when agents are informed about free-riders' reputation and play Defect, cooperation decreases. Finally, a combination of punishment and reputation-based partner selection leads to higher cooperation rates.
SSRN Electronic Journal, 2014
In dyadic models of indirect reciprocity, the receivers' history of giving has a significant impa... more In dyadic models of indirect reciprocity, the receivers' history of giving has a significant impact on the donor's decision. When the interaction involves more than two agents things become more complicated, and in large groups cooperation can hardly emerge. In this work we use a Public Goods Game to investigate whether publicly available reputation scores may support the evolution of cooperation and whether this is affected by the kind of network structure adopted. Moreover, if agents interact on a bipartite graph with partner selection cooperation can thrive in large groups and in a small amount of time.
Understanding Complex Systems, 2013
Why Read This Chapter? To understand the different conceptions underlying reputation in simulatio... more Why Read This Chapter? To understand the different conceptions underlying reputation in simulations up to the current time and to get to know some of the approaches to implementing reputation mechanisms, which are more cognitively sophisticated.
arXiv preprint arXiv:1106.4218, Jun 21, 2011
Abstract: The study of opinions, their formation and change, is one of the defining topics addres... more Abstract: The study of opinions, their formation and change, is one of the defining topics addressed by social psychology, but in recent years other disciplines, like computer science and complexity, have tried to deal with this issue. Despite the flourishing of different models and theories in both fields, several key questions still remain unanswered. The understanding of how opinions change and the way they are affected by social influence are challenging issues requiring a thorough analysis of opinion per se but also of the way in ...
arXiv preprint arXiv:1106.4221, Jun 21, 2011
Abstract: The study of opinions, their formation and change, is one of the defining topics addres... more Abstract: The study of opinions, their formation and change, is one of the defining topics addressed by social psychology, but in recent years other disciplines, as computer science and complexity, have addressed this challenge. Despite the flourishing of different models and theories in both fields, several key questions still remain unanswered. The aim of this paper is to challenge the current theories on opinion by putting forward a cognitively grounded model where opinions are described as specific mental representations whose ...
COGSCI 2010, Annual Meeting of the Cognitive Science Society 11-14 August 2010, Aug 1, 2010
People use sanctioning behaviours differently according to what they believe and want to achieve,... more People use sanctioning behaviours differently according to what they believe and want to achieve, according to the context and to the situation. We need to understand the motivations for different forms of punishment in order to explain why sanctions and incentives have different effects on human behaviour. Aim of this work is to propose a cognitive model of three distinct kinds of punishing behaviours, differentiated in terms of the defining cognitive patterns. Keywords: Cognitive modeling; Punishment; Cooperation.
Social Network Analysis and Mining
Gossip is a pervasive phenomenon in organizations causing many individuals to have second-hand in... more Gossip is a pervasive phenomenon in organizations causing many individuals to have second-hand information about their colleagues. However, whether it is used to inform friendship choices (i.e., friendship creation, friendship maintenance, friendship discontinuation) is not that evident. This paper articulates and empirically tests a complex contagion model to explain how gossip, through its reputational effects, can affect the evolution of friendship ties. We argue that hearing gossip from more than a single sender (and about several targets) impacts receivers’ friendships with the gossip targets. Hypotheses are tested in a two-wave sociometric panel study among 148 employees in a Dutch childcare organization. Stochastic actor-oriented models reveal positive gossip favors receiver-target friendships, whereas negative gossip inhibits them. We also find evidence supporting that, for damaging relationships, negative gossip needs to originate in more than a single sender. Positive goss...
In this work, we propose an evolutionary account of reactions to a wrong as an integrated set. Un... more In this work, we propose an evolutionary account of reactions to a wrong as an integrated set. Unlike other theories, we are not interested in revenge, punishment or sanction per se, but in their coexistence. We posit that this variety of reactions is needed in order to achieve different goals, but it also implies an increase in cognitive costs that requires to be explained from an evolutionary perspective. Moving from the identification of the psychological traits that uniquely define each reaction, two concurrent hypotheses are suggested and discussed: either the richness of human social life requests a variety of reactions, or the benefits of single reactions at the psychological level allowed these reactions to be maintained in the social life.
People use sanctioning behaviours differently according to what they believe and want to achieve,... more People use sanctioning behaviours differently according to what they believe and want to achieve, according to the context and to the situation. We need to understand the motivations for different forms of punishment in order to explain why sanctions and incentives have different effects on human behaviour. Aim of this work is to propose a cognitive model of three distinct kinds of punishing behaviours, differentiated in terms of the defining cognitive patterns.
The study of opinions, their formation and change, is one of the defining topics addressed by soc... more The study of opinions, their formation and change, is one of the defining topics addressed by social psychology, but in recent years other disciplines, as computer science and complexity, have addressed this challenge. Despite the flourishing of different models and theories in both fields, several key questions still remain unanswered. The aim of this paper is to challenge the current theories on opinion by putting forward a cognitively grounded model where opinions are described as specific mental representations whose main properties are put forward. A comparison with reputation will be also presented.
The Oxford Handbook of Gossip and Reputation, 2019
This introductory chapter sketches the contours of an emerging multidisciplinary and in terdiscip... more This introductory chapter sketches the contours of an emerging multidisciplinary and in terdisciplinary research program on the conceptual foundations, antecedents, dynamics, and consequences of gossip and reputation. It argues that this research agenda should be developed along three interrelated dimensions. First, gossip and reputation are multifac eted theoretical constructs that share at least six key characteristics. Both are relational and triadic, morally laden, multifunctional, and context-dependent social phenomena that have an evolutionary base and are subject to strategic behavior. Each of the chapters in this Handbook touches upon at least one of these facets. Second, in order to adequately capture this complexity, a multidisciplinary and eventually interdisciplinary approach is needed. Intradisciplinary progress is a precondition for high-quality multidisciplinary scholarship. Third, the frontier of much current research crystallizes around six substan tive problem domains, capturing different levels of analysis and their interplay.
Microeconomics: Welfare Economics & Collective Decision-Making eJournal, 2016
Reputation plays a major role in human societies, and it has been proposed as an explanation for ... more Reputation plays a major role in human societies, and it has been proposed as an explanation for the evolution of cooperation. While the majority of previous studies equates reputation with a transparent and complete history of players' past decisions, in real life, reputations are often ambiguous and opaque. Using web-based experiments, we explore the extent to which opaque reputation works in isolating defectors, with and without partner selection opportunities. Our results show that low reputation works as a signal of untrustworthiness, whereas medium or high reputation are not taken into account by participants for orienting their choices. We also find that reputation without partner selection does not promote cooperative behavior; that is, defectors do not turn into cooperators only for the sake of getting a positive reputation. Finally, in a third study, we find that, when reputation is pivotal to selection, then a substantial proportion of would-be defectors turn into coo...
Scientific Reports, 2016
Cooperation can be supported by indirect reciprocity via reputation. Thanks to gossip, reputation... more Cooperation can be supported by indirect reciprocity via reputation. Thanks to gossip, reputations are built and circulated and humans can identify defectors and ostracise them. However, the evolutionary stability of gossip is allegedly undermined by the fact that it is more error-prone that direct observation, whereas ostracism could be ineffective if the partner selection mechanism is not robust. The aim of this work is to investigate the conditions under which the combination of gossip and ostracism might support cooperation in groups of different sizes. We are also interested in exploring the extent to which errors in transmission might undermine the reliability of gossip as a mechanism for identifying defectors. Our results show that a large quantity of gossip is necessary to support cooperation, and that group structure can mitigate the effects of errors in transmission.
Reputation is one of the most effective solutions to the so-called «puzzle of cooperation», but i... more Reputation is one of the most effective solutions to the so-called «puzzle of cooperation», but it is usually studied in contexts in which information is not ambiguous and there are no incentives towards strategically using it. In this study, we test wheter the possibility of being evaluated (with a like or a dislike) when giving suggestions about a deal in a competitive game has an effect on truthfulness of suggestions. We designed a computer-mediated experiment and we tested adolescents in a high-school in Italy, with the aim of understanding the development of reputational dynamics and how adolescents deal with competing incentives. Our results show that when reputations introduced, adolescents become more cooperative, both in terms of donations to partners and of suggestions offered. We also observe that reputations, both positive and negative, behave as attractors, thus those of ill-repute receive negative reviews even when they cooperate, and individuals with positive reputati...
Journal of Artificial Societies and Social Simulation, 2021
The behavior of a heterogeneous population of individuals during an emergency, such as epidemics,... more The behavior of a heterogeneous population of individuals during an emergency, such as epidemics, natural disasters, terrorist attacks, is dynamic, emergent and complex. In this situation, reducing uncertainty about the event is crucial in order to identify and pursue the best possible course of action. People depend on experts, government sources, the media and fellow community members as potentially valid sources of information to reduce uncertainty, but their messages can be ambiguous, misleading or contradictory. E ective risk prevention depends on the way in which the population receives, elaborates and spread the message, and together these elements result in a collective perception of risk. The interaction between individuals' attitudes toward risk and institutions, the more or less alarmist way in which the information is reported and the role of the media can lead to risk perception that di ers from the original message, as well as to contrasting opinions about risk within the same population. The aim of this study is to bridge a model of opinion dynamics with the issue of uncertainty and trust in the sources, in order to understand the determinants of collective risk assessment. Our results show that alarming information spreads more easily than reassuring one, and that the media plays a key role in this. Concerning the role of internal variables, our simulation results show that risk sensitiveness has more influence on the final opinion than trust towards the institutional message. Furthermore, the role of di erent network structures seems to be negligible, even on two empirically calibrated network topologies, thus suggesting that knowing beforehand how much the public trusts their institutional representatives and how reactive they are to a certain risk might provide useful indications to design more e ective communication strategies during crises.
Frontiers in Psychology, 2019
Most of the current literature on gossip describes gossipmongers as incessantly sharing evaluativ... more Most of the current literature on gossip describes gossipmongers as incessantly sharing evaluative and valuable information about an absent third party in teams, groups, communities, and organizations. However, potential gossipers can similarly decide not to share what they know, depending on the content, the context, or their relationship with the other actors in the gossip triad. We argue that understanding the reasons why people do not gossip may provide useful insights into individual motives, group dynamics, and collective behaviors. This theoretical contribution first critically surveys the existing gossip literature with the aim of highlighting the conditions under which people might refrain from sharing third party information. We then propose to apply Goal Framing theory as a way to bridge a theory of the micro-foundations of human behavior with an analytical model of the gossip triad that disentangles the various ways through which senders, receivers, and objects of gossip may be interrelated. From a goal framing perspective, most research on gossip illustrates the mechanisms in which the hedonic gratification derived from gossiping is reinforced by gain or normative goals. However, a normative or a gain goal frame can prevent the gossip monger from spreading the information, and we argue that depending on different configurations of frames and relations between actors the perceived costs of sending gossip may be far higher than much of the previous literature suggests.
Scientific Reports, 2016
Cooperation can be supported by indirect reciprocity via reputation. Thanks to gossip, reputation... more Cooperation can be supported by indirect reciprocity via reputation. Thanks to gossip, reputations are built and circulated and humans can identify defectors and ostracise them. However, the evolutionary stability of gossip is allegedly undermined by the fact that it is more error-prone that direct observation, whereas ostracism could be ineffective if the partner selection mechanism is not robust. The aim of this work is to investigate the conditions under which the combination of gossip and ostracism might support cooperation in groups of different sizes. We are also interested in exploring the extent to which errors in transmission might undermine the reliability of gossip as a mechanism for identifying defectors. Our results show that a large quantity of gossip is necessary to support cooperation, and that group structure can mitigate the effects of errors in transmission.
Frontiers in Physics, 2015
The study of opinions-e.g., their formation and change, and their effects on our society-by means... more The study of opinions-e.g., their formation and change, and their effects on our society-by means of theoretical and numerical models has been one of the main goals of sociophysics until now, but it is one of the defining topics addressed by social psychology and complexity science. Despite the flourishing of different models and theories, several key questions still remain unanswered. The aim of this paper is to provide a cognitively grounded computational model of opinions in which they are described as mental representations and defined in terms of distinctive mental features. We also define how these representations change dynamically through different processes, describing the interplay between mental and social dynamics of opinions. We present two versions of the model, one with discrete opinions (voter model-like), and one with continuous ones (Deffuant-like). By means of numerical simulations, we compare the behavior of our cognitive model with the classical sociophysical models, and we identify interesting differences in the dynamics of consensus for each of the models considered.
In this work, we propose an evolutionary account of reactions to a wrong as an integrated set. Un... more In this work, we propose an evolutionary account of reactions to a wrong as an integrated set. Unlike other theories, we are not interested in revenge, punishment or sanction per se, but in their coexistence. We posit that this variety of reactions is needed in order to achieve different goals, but it also implies an increase in cognitive costs that requires to be explained from an evolutionary perspective. Moving from the identification of the psychological traits that uniquely define each reaction, two concurrent hypotheses are suggested and discussed: either the richness of human social life requests a variety of reactions, or the benefits of single reactions at the psychological level allowed these reactions to be maintained in the social life.
Lecture Notes in Computer Science, 2015
In an environment in which free-riders are better off than cooperators, social control is require... more In an environment in which free-riders are better off than cooperators, social control is required to foster and maintain cooperation. There are two main paths through which social control can be applied: punishment and reputation. Using a Public Goods Game, we show that gossip, used for assortment under three different strategies, can be effective in large groups, whereas its efficacy is reduced in small groups, with no main effect of the gossiping strategy. We also test four different combinations of gossip and costly punishment, showing that a combination of punishment and reputation-based partner selection leads to higher cooperation rates.
Advances in Intelligent Systems and Computing, 2014
In an environment in which free-riders are better off than cooperators, social control is require... more In an environment in which free-riders are better off than cooperators, social control is required to foster and maintain cooperation. There are two main paths through which social control can be applied: punishment and reputation. Our experiments explore the efficacy of punishment and reputation on cooperation rates, both in isolation and in combination. Using a Public Goods Game, we are interested in assessing how cooperation rates change when agents can play one of two different reactive strategies, i.e., they can pay a cost in order to reduce the payoff of free-riders, or they can know others' reputation and then either play defect with free-riders, or refuse to interact with them. Cooperation is maintained at a high level through punishment, but also reputation-based partner selection proves effective in maintaining cooperation. However, when agents are informed about free-riders' reputation and play Defect, cooperation decreases. Finally, a combination of punishment and reputation-based partner selection leads to higher cooperation rates.
SSRN Electronic Journal, 2014
In dyadic models of indirect reciprocity, the receivers' history of giving has a significant impa... more In dyadic models of indirect reciprocity, the receivers' history of giving has a significant impact on the donor's decision. When the interaction involves more than two agents things become more complicated, and in large groups cooperation can hardly emerge. In this work we use a Public Goods Game to investigate whether publicly available reputation scores may support the evolution of cooperation and whether this is affected by the kind of network structure adopted. Moreover, if agents interact on a bipartite graph with partner selection cooperation can thrive in large groups and in a small amount of time.
Understanding Complex Systems, 2013
Why Read This Chapter? To understand the different conceptions underlying reputation in simulatio... more Why Read This Chapter? To understand the different conceptions underlying reputation in simulations up to the current time and to get to know some of the approaches to implementing reputation mechanisms, which are more cognitively sophisticated.
arXiv preprint arXiv:1106.4218, Jun 21, 2011
Abstract: The study of opinions, their formation and change, is one of the defining topics addres... more Abstract: The study of opinions, their formation and change, is one of the defining topics addressed by social psychology, but in recent years other disciplines, like computer science and complexity, have tried to deal with this issue. Despite the flourishing of different models and theories in both fields, several key questions still remain unanswered. The understanding of how opinions change and the way they are affected by social influence are challenging issues requiring a thorough analysis of opinion per se but also of the way in ...
arXiv preprint arXiv:1106.4221, Jun 21, 2011
Abstract: The study of opinions, their formation and change, is one of the defining topics addres... more Abstract: The study of opinions, their formation and change, is one of the defining topics addressed by social psychology, but in recent years other disciplines, as computer science and complexity, have addressed this challenge. Despite the flourishing of different models and theories in both fields, several key questions still remain unanswered. The aim of this paper is to challenge the current theories on opinion by putting forward a cognitively grounded model where opinions are described as specific mental representations whose ...
COGSCI 2010, Annual Meeting of the Cognitive Science Society 11-14 August 2010, Aug 1, 2010
People use sanctioning behaviours differently according to what they believe and want to achieve,... more People use sanctioning behaviours differently according to what they believe and want to achieve, according to the context and to the situation. We need to understand the motivations for different forms of punishment in order to explain why sanctions and incentives have different effects on human behaviour. Aim of this work is to propose a cognitive model of three distinct kinds of punishing behaviours, differentiated in terms of the defining cognitive patterns. Keywords: Cognitive modeling; Punishment; Cooperation.