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  • 1.
    Eriksson, Kimmo
    et al.
    Mälardalen University, School of Education, Culture and Communication.
    Jansson, Fredrik
    Mälardalen University, School of Education, Culture and Communication.
    Sjöstrand, Jonas
    KTH.
    Bentley's conjecture on popularity toplist turnover under random copying2010In: The Ramanujan journal, ISSN 1382-4090, E-ISSN 1572-9303, Vol. 23, no 1, p. 371-396Article in journal (Refereed)
    Abstract [en]

    Bentley et al. studied the turnover rate in popularity toplists in a 'random copying' model of cultural evolution. Based on simulations of a model with population size N, list length ℓ and invention rate μ, they conjectured a remarkably simple formula for the turnover rate: ℓ √μ. Here we study an overlapping generations version of the random copying model, which can be interpreted as a random walk on the integer partitions of the population size. In this model we show that the conjectured formula, after a slight correction, holds asymptotically.

  • 2.
    Eriksson, Kimmo
    et al.
    Mälardalen University, School of Education, Culture and Communication.
    Jansson, Fredrik
    Mälardalen University, School of Education, Culture and Communication.
    Vetander, Thomas
    Mälardalen University, School of Education, Culture and Communication.
    The assignment game with negative externalities and bounded rationality2011In: International Game Theory Review, ISSN 0219-1989, Vol. 13, no 4, p. 443-459Article in journal (Refereed)
    Abstract [en]

    We introduce negative externalities in the form of ill will among the players of the classic two-sided assignment game of Shapley and Shubik, by letting each player's utility be negatively correlated with the payoff of all the players in his group. The new game is very complex, but under a certain assumption of bounded rationality we derive a straightforward notion of stable outcomes as certain conjectural equilibria. We prove that several well-known properties of the set of stable outcomes in the assignment game carry over to this new game. © 2011 World Scientific Publishing Company.

  • 3.
    Jansson, Fredrik
    Mälardalen University, School of Education, Culture and Communication, Educational Sciences and Mathematics.
    Modelling Two-Person Interactions Within and Between Cultural Groups2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The groups with which we associate influence our actions. This is often the case even when they are not deliberately organised but rather based on social categories, such as sex and skin colour, or cultural homogeneity, such as common language or customs. Group membership can cause widespread phenomena such as ingroup favouritism, polarisation of opinion and competition. Previous experiments have shown that these effects can be triggered by even completely arbitrary distinctions between groups. This thesis uses mathematical models to investigate under what circumstances these phenomena can arise.

    Using a game theoretical approach, the first three papers address the evolution of ingroup favouritism. Previous models have focused on the prisoners’ dilemma, interactions where the socially optimal behaviour is to co-operate, but where it is in the individual’s self-interest not to. The results presented here suggest that co-ordination problems may have been more important than those of co-operation in the evolution of an ingroup bias. In particular, this applies to common goals that require trust. It is also demonstrated in a behavioural experiment that such trust is most common within groups, but that it can emerge between groups through group reputation.

    The fourth paper focuses on a model on how cultural groups in contact can develop common norms, rather than polarise into different norm groups, by assuming a confirmation bias. The model is empirically tested on demographic and linguistic data from Mauritian Creole, a natural language developed from the mixing of parent languages.

    In the fifth paper, the group is defined by common preferences (e.g. for pop songs), which are transmitted in a random copying model. The competitive success of the groups, with respect to their size, is recorded on a toplist, the turnover rate of which is derived.

    In the final paper, people match up in pairs between groups according to their preferences, and all stable matchings are found under a specific assumption of bounded rationality, when people’s individual behaviour may be affected by the consequences for fellow group members.

  • 4.
    Jansson, Fredrik
    Stockholm University, Sweden.
    Pitfalls in Spatial Modelling of Ethnocentrism: A Simulation Analysis of the Model of Hammond and Axelrod2013In: JASSS: Journal of Artificial Societies and Social Simulation, ISSN 1460-7425, E-ISSN 1460-7425, Vol. 16, no 3Article in journal (Refereed)
    Abstract [en]

    Ethnocentrism refers to the tendency to behave differently towards strangers based only on whether they belong to the ingroup or the outgroup. It is a widespread phenomenon that can be triggered by arbitrary cues, but the origins of which is not clearly understood. In a recent simulation model by Hammond and Axelrod, an ingroup bias evolves in the prisoners’ dilemma game. However, it will be argued here that the model does little to advance our understanding of ethnocentrism. The model assumes a spatial structure in which agents interact only with their immediate neighbourhood, populated mostly by clones, and the marker becomes an approximate cue of whether the partner is one. It will be shown that agents with an ingroup bias are successful compared to unconditional cooperators since they only exclude non-clones, but are outcompeted by less error-prone kin identifiers. Thus, the results of the simulations can be explained by a simple form of kin selection. These findings illustrate how spatial assumptions can alter a model to the extent that it no longer describes the phenomenon under study.

  • 5.
    Jansson, Fredrik
    Mälardalen University, School of Education, Culture and Communication, Educational Sciences and Mathematics.
    What games support the evolution of an ingroup bias?2015In: Journal of Theoretical Biology, ISSN 0022-5193, E-ISSN 1095-8541, Vol. 373, p. 100-110Article in journal (Refereed)
    Abstract [en]

    There is an increasing wealth of models trying to explain the evolution of group discrimination and an ingroup bias. This paper sets out to systematically investigate the most fundamental assumption in these models: in what kind of situations do the interactions take place? What strategic structures - games - support the evolution of an ingroup bias? More specifically, the aim here is to find the prerequisites for when a bias also with respect to minimal groups - arbitrarily defined groups void of group-specific qualities - is selected for, and which cannot be ascribed to kin selection.Through analyses and simulations of minimal models of two-person games, this paper indicates that only some games are conducive to the evolution of ingroup favouritism. In particular, this class does not contain the prisoners[U+05F3] dilemma, but it does contain anti-co-ordination and co-ordination games. Contrasting to the prisoners[U+05F3] dilemma, these are games where it is not a matter of whether to behave altruistically, but rather one of predicting what the other person will be doing, and where I would benefit from you knowing my intentions.In anti-co-ordination games, on average, not only will agents discriminate between groups, but also in such a way that their choices maximise the sum of the available payoffs towards the ingroup more often than towards the outgroup. And in co-ordination games, even if agents do manage to co-ordinate with the whole population, they are more likely to co-ordinate on the socially optimal equilibrium within their group. Simulations show that this occurs most often in games where there is a component of risk-taking, and thus trust, involved. A typical such game is the stag hunt or assurance game. 

  • 6.
    Jansson, Fredrik
    Mälardalen University, School of Education, Culture and Communication.
    What Strategic Structures Support the Evolution of Ethnocentrism?Manuscript (preprint) (Other academic)
    Abstract [en]

    Game theory deals with the impact of strategic structure on interactions. It is of course not known what strategic structures (i.e., games) dominated interactions in the evolutionary past of humans. Evolutionary models often uncritically assume some game, typically some kind of the prisoners’ dilemma, to investigate the effects of some other feature of the model. Here, another approach is suggested: What can be said about the likely strategic structure of interactions, given the features of human evolved psychology? The feature considered in this paper is ethnocentrism (also known as ingroup bias), which refers to the tendency to behave differently to different strangers simply depending on whether they seem to belong to the ingroup or the outgroup. Analysis and simulations of simple evolutionary models indicate that only some strategic structures are conducive to the evolution of ethnocentrism. In particular, this class does not contain the prisoners’ dilemma, but it does contain anti-coordination and coordination games, with socially optimal strategies being more frequent in ingroup interactions in the latter, especially if the other strategy is risk dominant, which applies to a class of games known as the stag hunt. This indicates that the strategic structure of coordination games, such as the stag hunt, and anti-coordination games, such as hawk-dove, may have been more common than games of cooperation and defection in human’s evolutionary past.

  • 7.
    Jansson, Fredrik
    et al.
    Mälardalen University, School of Education, Culture and Communication.
    Eriksson, Kimmo
    Mälardalen University, School of Education, Culture and Communication.
    Trusting You Trusting Me: The Importance of Beliefs about Trust in the Stag Hunt/Assurance GameManuscript (preprint) (Other academic)
    Abstract [en]

    In the coordination game known as the stag hunt or the assurance game, players face a choice between a risk-free strategy and a risky strategy that pays higher if chosen also by the other player. Such games are commonly described as trust problems because the risky strategy is a rational choice only if one expects the other player to choose it. Here we argue that the stag hunt ought to be about trust only in an indirect and recursive waywhere beliefs about trust are more important than actual trust. On the basis of an established trust questionnaire we categorised 323 participants as having either high or low trust. They then played series of stag hunt games with varying amounts of information (either none, or private or common) about trust levels of involved parties. In line with our predictions, a player’s strategy choice was not strongly predicted by his or her trust level unless the latter was common knowledge. In other words, a high (low) truster Ego is more likely to play the risky (risk-free) strategy if Ego knows that Alter knows Ego’s trust level, emphasising the importance of beliefs about trust.

  • 8.
    Jansson, Fredrik
    et al.
    Stockholms universitet, Centrum för evolutionär kulturforskning.
    Lindenfors, Patrik
    Stockholms universitet, Avdelningen för zoologisk ekologi.
    Sandberg, Mikael
    Department of Zoology, Stockholm University.
    Democratic revolutions as institutional innovation diffusion: rapid adoption and survival of democracy2013In: Technological forecasting & social change, ISSN 0040-1625, E-ISSN 1873-5509, Vol. 80, no 8, p. 1546-1556Article in journal (Refereed)
    Abstract [en]

    Recent ‘democratic revolutions’ in Islamic countries call for a re-consideration of transitions to and from democracy. Transitions to democracy have often been considered the outcome of socio-economic modernization and therefore slow and incremental processes. But as a recent study has made clear, in the last century, transitions to democracy have mainly occurred through rapid leaps rather than slow and incremental steps. Here, we therefore apply an innovation and systems perspective and consider transitions to democracy as processes of institutional, and therefore systemic, innovation adoption. We show that transitions to democracy starting before 1900 lasted for an average of 50 years and a median of 56 years, while transitions originating later took an average of 4.6 years and a median of 1.7 years. However, our results indicate that the survival time of democratic regimes is longer in cases where the transition periods have also been longer, suggesting that patience paid in previous democratizations. We identify a critical ‘consolidation-preparing’ transition period of 12 years. Our results also show that in cases where the transitions have not been made directly from autocracy to democracy, there are no main institutional paths towards democracy. Instead, democracy seems reachable from a variety of directions. This is in line with the analogy of diffusion of innovations at the nation systems level, for which assumptions are that potential adopter systems may vary in susceptibility over time. The adoption of the institutions of democracy therefore corresponds to the adoption of a new political communications standard for a nation, in this case the innovation of involving in principle all adult citizens on an equal basis.

  • 9.
    Jansson, Fredrik
    et al.
    Mälardalen University, School of Education, Culture and Communication.
    Strimling, Pontus
    Stockholms universitet, Stockholm University.
    Parkvall, Mikael
    Stockholms universitet, Stockholm University.
    Modelling the Evolution of CreolesManuscript (preprint) (Other academic)
    Abstract [en]

    Various theories have been proposed regarding the origin of creole languages. Describing a process where only the end result is documented involves dealing with several methodological difficulties. In this paper we try to deal with some of the issues by using a novel mathematical model together with detailed empirical data on the origin and structure of Mauritian Creole. Our main focus is on whetherMauritian Creole may have been created only from a mutual desire to communicate, without a target language or prestige bias. Our conclusions are affirmative. With a confirmation bias towards learning from successful communication, the model predicts Mauritian Creole better than any of the input languages, including the lexifier French, thus providing a compelling and specific hypothetical model of how creoles are created. The results also show that it may be possible for a creole to develop quickly after first contact, and that it was created mostly from material found in the input languages, but without inheriting their morphology.

  • 10.
    Lindenfors, Patrik
    et al.
    Stockholms universitet.
    Jansson, Fredrik
    Mälardalen University, School of Education, Culture and Communication.
    Sandberg, Mikael
    Stockholms universitet.
    The Cultural Evolution of Democracy: Saltational Changes in a Political Regime Landscape2011In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 6, no 11, p. e28270-Article in journal (Refereed)
    Abstract [en]

    Transitions to democracy are most often considered the outcome of historical modernization processes. Socio-economic changes, such as increases in per capita GNP, education levels, urbanization and communication, have traditionally been found to be correlates or 'requisites' of democratic reform. However, transition times and the number of reform steps have not been studied comprehensively. Here we show that historically, transitions to democracy have mainly occurred through rapid leaps rather than slow and incremental transition steps, with a median time from autocracy to democracy of 2.4 years, and overnight in the reverse direction. Our results show that autocracy and democracy have acted as peaks in an evolutionary landscape of possible modes of institutional arrangements. Only scarcely have there been slow incremental transitions. We discuss our results in relation to the application of phylogenetic comparative methods in cultural evolution and point out that the evolving unit in this system is the institutional arrangement, not the individual country which is instead better regarded as the 'host' for the political system.

  • 11.
    Lindenfors, Patrik
    et al.
    Stockholms universitet.
    Sandberg, Mikael
    Högskolan i Halmstad.
    Jansson, Fredrik
    Mälardalen University, School of Education, Culture and Communication.
    Demokratins evolution2012In: Gaudeamus, ISSN 0016-5247, no 1, p. 14-15Article in journal (Other (popular science, discussion, etc.))
  • 12.
    Lindenfors, Patrik
    et al.
    Stockholms universitet, Avdelningen för zoologisk ekologi.
    Sandberg, Mikael
    Högskolan i Halmstad.
    Jansson, Fredrik
    Mälardalen University, School of Education, Culture and Communication. Stockholms universitet, Centrum för evolutionär kulturforskning.
    Plötslig demokrati: Vad statsvetenskapen kan lära av evolutionsbiologin.2012Other (Other (popular science, discussion, etc.))
1 - 12 of 12
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