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Copula Information, Guerras Meméticas, Polarização Social e Difusão de Inovação

Alguns artigos dos meu amigos Renato Vicente, Nestor Caticha e colaboradores. Imagino que colocaram o último, sobre culture wars, depois que o Serra apelou para táticas terroristas religiosas na internet. Será? 

The cultural war in America is between two sides that go by different names. The most common are Conservative vs. Liberal, Right vs. Left, and Republicans vs. Democrats.


Professor James Davison Hunter has written several books on the cultural war.  He uses the terms “orthodox” and “progressive” to decribe the two sides in his book, Culture Wars: The Struggle to Define America. He has chosen his words carefully to depict each side. “Orthodox” gives a feeling of respect for past, time-honored traditions. “Progressives” captures how liberals see themselves — optimistic, creative and making progress away from old-fashioned virtues and toward a brave new world with constantly changing rules and values.

The inside cover of his book says “Abortion, funding for the arts, women’s rights — the list of controversies that divide our nation runs long and each one cuts deep.  This book shows that these issues are not isolated from one another but are, in fact, part of a fabric of conflict which constitutes nothing short of a struggle over the meaning of America.”

“Culture Wars presents a riveting account of how Christian fundamentalists, Orthodox Jews, and conservative Catholics have joined forces in a fierce battle against their progressive counterparts — secularists, reform Jews, liberal Catholics and Protestants — as each struggles to gain control over such fields of conflict as the family, art, education, law and politics. Not since the Civil War has there been such fundamental disagreement over basic assumptions about truth, freedom, and our national identity.” The public debates “are topics of dispute at the corporate cocktail party and the factory cafeteria alike, in the high school civics classroom, in the church lounge after the weekly sermon, and at the kitchen table over the evening meal.  Few of us leave these discussions without ardently voicing our own opinions on the matter at hand.  Such passion is completely understandable.  These are, after all, discussions about what is fundamentally right and wrong about the world we live in — about what is ultimately good what is finally intolerable in our communities.”

Signatures of the neurocognitive basis of culture wars found in moral psychology data

segunda-feira, 31 de maio de 2010, 15:31:34 | Nestor CatichaIr para artigo inteiro
Moral Foundation Theory (MFT) states that groups of different observers may rely on partially dissimilar sets of moral foundations, thereby reaching different moral valuations on a subset of issues. With the introduction of functional imaging techniques, a wealth of new data on neurocognitive processes has rapidly mounted and it has become increasingly more evident that this type of data should provide an adequate basis for modeling social systems. In particular, it has been shown that there is a spectrum of cognitive styles with respect to the differential handling of novel or corroborating information. Furthermore this spectrum is correlated to political affiliation. Here we use methods of statistical mechanics to characterize the collective behavior of an agent-based model society whose inter individual interactions due to information exchange in the form of opinions, are in qualitative agreement with neurocognitive and psychological data. The main conclusion derived from the model is that the existence of diversity in the cognitive strategies yields different statistics for the sets of moral foundations and that these arise from the cognitive interactions of the agents. Thus a simple interacting agent model, whose interactions are in accord with empirical data about moral dynamics, presents statistical signatures consistent with those that characterize opinions of conservatives and liberals. The higher the difference in the treatment of novel and corroborating information the more agents correlate to liberals.

An information theoretic approach to statistical dependence: copula information

sábado, 21 de novembro de 2009, 19:41:35 | Rafael S. CalsaveriniIr para artigo inteiro
We discuss the connection between information and copula theories by showing that a copula can be employed to decompose the information content of a multivariate distribution into marginal and dependence components, with the latter quantified by the mutual information. We define the information excess as a measure of deviation from a maximum entropy distribution. The idea of marginal invariant dependence measures is also discussed and used to show that empirical linear correlation underestimates the amplitude of the actual correlation in the case of non-Gaussian marginals. The mutual information is shown to provide an upper bound for the asymptotic empirical log-likelihood of a copula. An analytical expression for the information excess of T-copulas is provided, allowing for simple model identification within this family. We illustrate the framework in a financial data set.

An Opinion Dynamics Model for the Diffusion of Innovations

quinta-feira, 12 de fevereiro de 2009, 11:53:49 | Andre C. R. MartinsIr para artigo inteiro
We study the dynamics of the adoption of new products by agents with continuous opinions and discrete actions (CODA). The model is such that the refusal in adopting a new idea or product is increasingly weighted by neighbor agents as evidence against the product. Under these rules, we study the distribution of adoption times and the final proportion of adopters in the population. We compare the cases where initial adopters are clustered to the case where they are randomly scattered around the social network and investigate small world effects on the final proportion of adopters. The model predicts a fat tailed distribution for late adopters which is verified by empirical data.

Opinion Dynamics of Learning Agents: Does Seeking Consensus Lead to Disagreement?

quinta-feira, 29 de janeiro de 2009, 00:17:41 | Renato VicenteIr para artigo inteiro
We study opinion dynamics in a population of interacting adaptive agents voting on a set of complex multidimensional issues. We consider agents which can classify issues into for or against. The agents arrive at the opinions about each issue in question using an adaptive algorithm. Adaptation comes from learning and the information for the learning process comes from interacting with other neighboring agents and trying to change the internal state in order to concur with their opinions. The change in the internal state is driven by the information contained in the issue and in the opinion of the other agent. We present results in a simple yet rich context where each agent uses a Boolean Perceptron to state its opinion. If there is no internal clock, so the update occurs with asynchronously exchanged information among pairs of agents, then the typical case, if the number of issues is kept small, is the evolution into a society thorn by the emergence of factions with extreme opposite beliefs. This occurs even when seeking consensus with agents with opposite opinions. The curious result is that it is learning from those that hold the same opinions that drives the emergence of factions. This results follows from the fact that factions are prevented by not learning at all from those agents that hold the same opinion. If the number of issues is large, the dynamics becomes trapped and the society does not evolve into factions and a distribution of moderate opinions is observed. We also study the less realistic, but technically simpler synchronous case showing that global consensus is a fixed point. However, the approach to this consensus is glassy in the limit of large societies if agents adapt even in the case of agreement.
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