http://jasss.soc.surrey.ac.uk Journal of Artificial Societies and Social Simulation: For the exploration and understanding of social processes by means of computer simulation en-GB Copyright Journal of Artificial Societies and Social Simulation Tue, 30 Jun 2020 20:45:18 +0000 jasss@jasss.org (Flaminio Squazzoni) http://jasss.soc.surrey.ac.uk/gifs/JASSS-small.jpg http://jasss.soc.surrey.ac.uk angelos@intelligence.tuc.gr (Angelos Chliaoutakis and Georgios Chalkiadakis) Article http://jasss.soc.surrey.ac.uk/23/3/10.html http://jasss.soc.surrey.ac.uk/23/3/10.html Tue, 30 Jun 2020 12:59:00 +0000 Angelos Chliaoutakis and Georgios Chalkiadakis: Social and computational archaeology focuses largely on the study of past societies and the evolution of human behaviour. At the same time, agent-based models (ABMs) allow the efficient modeling of human agency, and the quantitative representation and exploration of specific properties and patterns in archaeological information. In this work we put forward a novel agent-based trading model, for simulating the exchange and distribution of resources across settlements in past societies. The model is part of a broader ABM populated with autonomous, utility-seeking agents corresponding to households; with the ability to employ any spatial interaction model of choice. As such, it allows the study of the settlements’ trading ability and power, given their geo-location and their position within the trading network, and the structural properties of the network itself. As a case study we use the Minoan society during the Bronze Age, in the wider area of "Knossos" on the island of Crete, Greece. We instantiate two well-known spatial interaction sub-models, XTENT and Gravity, and conduct a systematic evaluation of the dynamic trading network that is formed over time. Our simulations assess the sustainability of the artificial Minoan society in terms of population size, number and distribution of agent communities, with respect to the available archaeological data and spatial interaction model employed; and, further, evaluate the resulting trading network’s structure (centrality, clustering, etc.) and how it affects inter-settlement organization, providing in the process insights and support for archaeological hypotheses on the settlement organization in place at the time. Our results show that when the trading network is modeled using Gravity, which focuses on the settlements' "importance" rather than proximity to each other, settlement numbers’ evolution patterns emerge that are similar to the ones that exist in the archaeological record. It can also be inferred by our simulations that a rather dense trading network, without a strict settlement hierarchy, could have emerged during the Late Minoan period, after the Theran volcanic eruption, a well documented historic catastrophic event. Moreover, it appears that the trading network's structure and interaction patterns are reversed after the Theran eruption, when compared to those in effect in earlier periods. schweighofer@csh.ac.at (Simon Schweighofer, Frank Schweitzer and David Garcia) Article http://jasss.soc.surrey.ac.uk/23/3/5.html http://jasss.soc.surrey.ac.uk/23/3/5.html Tue, 30 Jun 2020 12:58:00 +0000 Simon Schweighofer, Frank Schweitzer and David Garcia: Polarization is threatening the stability of democratic societies. Until now, polarization research has focused on opinion extremeness, overlooking the correlation between different policy issues. In this paper, we explain the emergence of hyperpolarization, i.e., the combination of extremeness and correlation between issues, by developing a new theory of opinion formation called "Weighted Balance Theory (WBT)". WBT extends Heider's cognitive balance theory to encompass multiple weighted attitudes. We validated WBT on empirical data from the 2016 National Election Survey. Furthermore, we developed an opinion dynamics model based on WBT, which, for the first time, is able to generate hyperpolarization and to explain the link between affective and opinion polarization. Finally, our theory encompasses other phenomena of opinion dynamics, including mono-polarization and backfire effects. n.s.malleson@leeds.ac.uk (Nick Malleson, Kevin Minors, Le-Minh Kieu, Jonathan A. Ward, Andrew West and Alison Heppenstall) Article http://jasss.soc.surrey.ac.uk/23/3/3.html http://jasss.soc.surrey.ac.uk/23/3/3.html Tue, 30 Jun 2020 12:57:00 +0000 Nick Malleson, Kevin Minors, Le-Minh Kieu, Jonathan A. Ward, Andrew West and Alison Heppenstall: Agent-based modelling is a valuable approach for modelling systems whose behaviour is driven by the interactions between distinct entities, such as crowds of people. However, it faces a fundamental difficulty: there are no established mechanisms for dynamically incorporating real-time data into models. This limits simulations that are inherently dynamic, such as those of pedestrian movements, to scenario testing on historic patterns rather than real-time simulation of the present. This paper demonstrates how a particle filter could be used to incorporate data into an agent-based model of pedestrian movements at run time. The experiments show that although it is possible to use a particle filter to perform online (real time) model optimisation, the number of individual particles required (and hence the computational complexity) increases exponentially with the number of agents. Furthermore, the paper assumes a one-to-one mapping between observations and individual agents, which would not be the case in reality. Therefore this paper lays some of the fundamental groundwork and highlights the key challenges that need to be addressed for the real-time simulation of crowd movements to become a reality. Such success could have implications for the management of complex environments both nationally and internationally such as transportation hubs, hospitals, shopping centres, etc. timoteo.carletti@unamur.be (Timoteo Carletti, Alessio Guarino, Andrea Guazzini and Federica Stefanelli) Article http://jasss.soc.surrey.ac.uk/23/3/4.html http://jasss.soc.surrey.ac.uk/23/3/4.html Tue, 30 Jun 2020 12:56:00 +0000 Timoteo Carletti, Alessio Guarino, Andrea Guazzini and Federica Stefanelli: People tend to form groups when they have to solve difficult problems because groups seem to have better problem-solving capabilities than individuals. Indeed, during their evolution, human beings learned that cooperation is frequently an optimal strategy to solve hard problems both quickly and accurately. The ability of a group to determine a solution to a given problem, once group members alone cannot, has been called "Collective Intelligence". Such emergent property of the group as a whole is the result of a complex interaction between many factors. Here, we propose a simple and analytically solvable model disentangling the direct link between collective intelligence and the average intelligence of group members. We found that there is a non-linear relation between the collective intelligence of a group and the average intelligence quotient of its members depending on task difficulty. We found three regimes as follows: for simple tasks, the level of collective intelligence of a group is a decreasing function of teammates' intelligence quotient; when tasks have intermediate difficulties, the relation between collective intelligence and intelligence quotient shows a non-monotone behaviour; for complex tasks, the level of collective intelligence of a group monotonically increases with teammates' intelligence quotient with phase transitions emerging when varying the latter's level. Although simple and abstract, our model paves the way for future experimental explorations of the link between task complexity, individual intelligence and group performance. ce.garciad@javeriana.edu.co (Carlos Córdoba and César García-Díaz) Article http://jasss.soc.surrey.ac.uk/23/3/9.html http://jasss.soc.surrey.ac.uk/23/3/9.html Tue, 30 Jun 2020 12:55:00 +0000 Carlos Córdoba and César García-Díaz: Reflexive phenomena are usually understood in the social sciences as processes that affect themselves recursively. This stems from the mutual altering relationship between participants and the social process they belong to: participants can change the course of the process with their actions and a new state during the evolution of the process can lead to a change in its participants' behavior. This article proposes an agent-based model of diffusion of innovations in a social network to study reflexivity. In this model, agents decide to adopt a new product according to a utility function that depends on two kinds of social influences. First, there is a local influence exerted on an agent by her closest neighbors that have already adopted, and also by herself if she feels the product suits her personal needs. Second, there is a global influence which leads agents to adopt when they become aware of emerging trends happening in the system. For this, we endow agents with a reflexive capacity that allows them to recognize a trend, even if they can not perceive a significant change in their neighborhood. Results reveal the appearance of slowdown periods along the adoption rate curve, in contrast with the classic stylized bell-shaped behavior. Results also show that network structure plays an important role in the effect of reflexivity: while some structures (e.g., scale-free networks) may amplify it, others (e.g., small-world structure) weaken such an effect. The contribution of this work lies in the inclusion of evolving cognitive distinctions as agents decide product adoption in diffusion processes. rosemary.penny.10@alumni.ucl.ac.uk (Rosemary Pepys, Robert Bowles and Noémie Bouhana) Article http://jasss.soc.surrey.ac.uk/23/3/12.html http://jasss.soc.surrey.ac.uk/23/3/12.html Tue, 30 Jun 2020 12:54:00 +0000 Rosemary Pepys, Robert Bowles and Noémie Bouhana: This paper presents a simulation model describing the radicalisation process. The radicalisation process is a complex human socio-environmental process which has been of much academic interest for the past two decades. Despite this it is still poorly understood and is an extremely difficult area for social scientists to research. It is a subject which suffers from a lack of available data, making the construction of an effective simulation model particularly challenging. In order to construct the simulation in this paper we rely on a theoretical framework which was originally developed as a means of synthesising the academic literature on radicalisation. This theoretical framework has three levels: individual vulnerability to radicalisation, exposure to radicalising moral contexts, and the emergence of radicalising settings. We adapt this framework into a simulation model by first re-constructing it as an individual-level state-transition model. Next, appropriate data is sought to parameterise the model. A parallel is drawn between the process of radicalisation and the process by which people develop the propensity to participate in more general acts of criminality; this analogy enables considerably more data to be used in parameterisation. The model is then calibrated by considering the logical differences between crime and terrorism which might lead to differences in the radicalisation and criminality development processes. The model is validated against stylised facts, demonstrating that despite being highly theoretical the simulation is capable of producing a realistic output. Possible uses of the model to evaluate the effectiveness of counter-radicalisation measures are also considered. czuprynm@uek.krakow.pl (Marcin Czupryna, Christian Franzke, Sascha Hokamp and Jürgen Scheffran) Article http://jasss.soc.surrey.ac.uk/23/3/7.html http://jasss.soc.surrey.ac.uk/23/3/7.html Tue, 30 Jun 2020 12:53:00 +0000 Marcin Czupryna, Christian Franzke, Sascha Hokamp and Jürgen Scheffran: There is an ongoing discussion concerning the relationship between social welfare and climate change, and thus the required level and type of measures needed to protect the climate. Integrated assessment models (IAMs) have been extended to incorporate technological progress, heterogeneity and uncertainty, making use of a (stochastic) dynamic equilibrium approach in order to derive a solution. According to the literature, the IAM class of models does not take all the relationships among economic, social and environmental factors into account. Moreover, it does not consider these interdependencies at the micro-level, meaning that all possible consequences are not duly examined. Here, we propose an agent-based approach to analyse the relationship between economic welfare and climate protection. In particular, our aim is to analyse how the decisions of individual agents, allowing for the trade-off between economic welfare and climate protection, influence the aggregated emergent economic behaviour. Using this model, we estimate a damage function, with values in the order 3% - 4%for 2 C temperature increase and having a linear (or slightly concave) shape. We show that the heterogeneity of the agents, technological progress and the damage function may lead to lower GDP growth rates and greater temperature-related damage than what is forecast by models with solely homogeneous (representative) agents. t.vu@sheffield.ac.uk (Tuong Manh Vu, Charlotte Probst, Alexandra Nielsen, Hao Bai, Petra S. Meier, Charlotte Buckley, Mark Strong, Alan Brennan and Robin C. Purshouse) Article http://jasss.soc.surrey.ac.uk/23/3/1.html http://jasss.soc.surrey.ac.uk/23/3/1.html Tue, 30 Jun 2020 12:52:00 +0000 Tuong Manh Vu, Charlotte Probst, Alexandra Nielsen, Hao Bai, Petra S. Meier, Charlotte Buckley, Mark Strong, Alan Brennan and Robin C. Purshouse: This paper introduces the MBSSM (Mechanism-Based Social Systems Modelling) software architecture that is designed for expressing mechanisms of social theories with individual behaviour components in a unified way and implementing these mechanisms in an agent-based simulation model. The MBSSM architecture is based on a middle-range theory approach most recently expounded by analytical sociology and is designed in the object-oriented programming paradigm with Unified Modelling Language diagrams. This paper presents two worked examples of using the architecture for modelling individual behaviour mechanisms that give rise to the dynamics of population-level alcohol use: a single-theory model of norm theory and a multi-theory model that combines norm theory with role theory. The MBSSM architecture provides a computational environment within which theories based on social mechanisms can be represented, compared, and integrated. The architecture plays a fundamental enabling role within a wider simulation model-based framework of abductive reasoning in which families of theories are tested for their ability to explain concrete social phenomena. czuprynm@uek.krakow.pl (Marcin Czupryna, Michał Jakubczyk and Paweł Oleksy) Article http://jasss.soc.surrey.ac.uk/23/3/11.html http://jasss.soc.surrey.ac.uk/23/3/11.html Tue, 30 Jun 2020 12:51:00 +0000 Marcin Czupryna, Michał Jakubczyk and Paweł Oleksy: What drives the prices of fine wines is not easy to discern, in view of a multitude of confounding factors characterising the transactions across several markets. At the same time, understanding the quantitative relationships and mechanisms that determine the price level is important for policy making (e.g. predicting the outcomes of regulations) and methodological purposes (which elements to consider in modelling these markets). We examine the price formation of fine wines simultaneously across three markets: an automated electronic exchange (Liv-ex), intermediated auctions, and over-the-counter (OTC). We use a unique dataset consisting of 99,769 price data points for Premier Cru Bordeaux fine wines and we examine the price determinants with Bayesian modelling. We ascertain the mean price ranking (OTC market being the most expensive and Liv-ex the least, differing by about 4.5% and -0.8% from the auctions). We also find a slight price decrease for larger transactions (approx.~0.3% reduction for a 10% volume increase) and some platykurtosis in price distribution (greatest in Liv-ex), and observe the most stochastic noise in auctions. In an agent-based simulation, we discover that it is necessary to include trading mechanisms, commissions, and OTC market heterogeneity to reproduce the observed characteristics. Our results indicate which elements should be included in future fine wine markets models. hirano@g.ecc.u-tokyo.ac.jp (Masanori Hirano, Kiyoshi Izumi, Hiroyasu Matsushima and Hiroki Sakaji) Article http://jasss.soc.surrey.ac.uk/23/3/6.html http://jasss.soc.surrey.ac.uk/23/3/6.html Tue, 30 Jun 2020 12:50:00 +0000 Masanori Hirano, Kiyoshi Izumi, Hiroyasu Matsushima and Hiroki Sakaji: Recently financial markets have shown significant risks and levels of volatility. Understanding the sources of these risks require simulation models capable of representing adequately the real mechanisms of markets. In this paper, we compared data of the high-frequency-trader market-making (HFT-MM) strategy from both the real financial market and our simulation. Regarding the former, we extracted trader clusters and identified one cluster whose statistical indexes indicated HFT-MM features. We then analyzed the difference between these traders' orders and the market price. In our simulation, we built an artificial market model with a continuous double auction system, stylized trader agents, and HFT-MM trader agents based on prior research. As an experiment, we compared the distribution of the order placements of HFT-MM traders in the real and simulated financial data. We found that the order placement distribution near the market or best price in both the real data and the simulations were similar. However, the orders far from the market or best price differed significantly when the real data exhibited a wider range of orders. This indicates that in order to build more realistic simulation of financial markets, integrating fine-grained data is essential. hezhou@ucas.ac.cn (Xianhua Wei, Aiya Li and Zhou He) Article http://jasss.soc.surrey.ac.uk/23/3/2.html http://jasss.soc.surrey.ac.uk/23/3/2.html Tue, 30 Jun 2020 12:49:00 +0000 Xianhua Wei, Aiya Li and Zhou He: Blockchain can be viewed as a public ledger maintained collectively by a large number of participators based on consensus protocol. We are interested in how difference consensus protocols and trade network topologies affect the performance of a blockchain system, which has not been studied in the literature yet. In this paper, we proposed an agent-based model consisting of multiple trader and miner agents, and one system agent. We investigated three consensus protocols, namely proof-of-work (PoW), proof-of-stake (PoS), and delegated proof-of-stake (DPoS). We also examined three common trade network topologies: random, small-world, and scale-free. We find that both consensus protocol and trade network topology can impact the performance of blockchain system. PoS and DPoS are generally better than PoW in terms of increasing trade efficiency and equalizing wealth. Besides, scale-free trade network is not favorable because its trade efficiency is quite low, which moderates the price fluctuation and wealth inequality. Since connectivity inequality determines wealth inequality, it is crucial to increase the connectivity among participants when designing a sustainable blockchain system. We suggest that our findings could be useful to the designers, practitioner and researchers of blockchain system and token economy. thomas.feliciani@ucd.ie (Thomas Feliciani, Ramanathan Moorthy, Pablo Lucas and Kalpana Shankar) Article http://jasss.soc.surrey.ac.uk/23/3/8.html http://jasss.soc.surrey.ac.uk/23/3/8.html Tue, 30 Jun 2020 12:48:00 +0000 Thomas Feliciani, Ramanathan Moorthy, Pablo Lucas and Kalpana Shankar: Simulation models have proven to be valuable tools for studying peer review processes. However, the effects of some of these models’ assumptions have not been tested, nor have these models been examined in comparative contexts. In this paper, we address two of these assumptions which go in tandem: (1) on the granularity of the evaluation scale, and (2) on the homogeneity of the grade language (i.e. whether reviewers interpret evaluation grades in the same fashion). We test the consequences of these assumptions by extending a well-known agent-based model of author and reviewer behaviour with discrete evaluation scales and reviewers’ interpretation of the grade language. In this way, we compare a peer review model with a homogeneous grade language, as assumed in most models of peer review, with a more psychologically realistic model where reviewers interpret the grades of the evaluation scale heterogeneously. We find that grade language heterogeneity can indeed affect the predictions of a model of peer review. frederic.amblard@ut-capitole.fr (Frederic Amblard) Review http://jasss.soc.surrey.ac.uk/23/3/reviews/1.html http://jasss.soc.surrey.ac.uk/23/3/reviews/1.html Tue, 30 Jun 2020 12:47:00 +0000 Review of: New Frontiers in the Study of Social Phenomena by Frederico Cecconi (ed.), reviewed by Frederic Amblard