Reply to Will and Hegselmann

[No abstract]Replication, Social Dilemmas, Simulation Methodology, Cooperation, Trust, Agent-Based Modelling

Local Convergence and Global Diversity: The Robustness of Cultural Homophily

Recent extensions of the Axelrod model of cultural dissemination (Klemm et al 2003) showed that global diversity is extremely fragile with small amounts of cultural mutation. This seemed to undermine the original Axelrod theory that homophily preserves diversity. We show that cultural diversity is surprisingly robust if we increase the tendency towards homophily as follows. First, we raised the threshold of similarity below which influence is precluded. Second, we allowed agents to be influenced by all neighbors simultaneously, instead of only one neighbor as assumed in the orginal model. Computational experiments show how both modifications strongly increase the robustness of diversity against mutation. We also find that our extensions may reverse at least one of the main results of Axelrod. While Axelrod predicted that a larger number of cultural dimensions (features) reduces diversity, we find that more features may entail higher levels of diversity.Comment: 21 pages, 8 figures, Submitted for presentation in Mathematical Sociology Session, Annual Meeting of the American Sociological Association (ASA), 200

The Surprising Success of a Replication That Failed

In a recent paper (jasss.soc.surrey.ac.uk/12/4/11.html), Oliver Will contends that the effect of mobility on trust that we originally reported (2002) depends on \'an assumption that is most probably an unwilling, unintended, and unwanted implication of the code.\' When we experimented with Will\'s revised model, we came to the opposite conclusion: his version provides stronger support for our theory than does our original. The explanation is that Will left the learning rate at the upper limit of 1.0, the level we assumed in our original paper. When we lowered the learning rate to compensate for the removal of the contested assumption, the results showed how mobility can lead to an increase in trust, which is consistent with our explanation for higher trust in the US compared to Japan. Moreover, the model also shows that it is possible for there to be too much mobility.Trust, Mobility, Replication

Automated Hate Speech Detection and the Problem of Offensive Language

A key challenge for automatic hate-speech detection on social media is the separation of hate speech from other instances of offensive language. Lexical detection methods tend to have low precision because they classify all messages containing particular terms as hate speech and previous work using supervised learning has failed to distinguish between the two categories. We used a crowd-sourced hate speech lexicon to collect tweets containing hate speech keywords. We use crowd-sourcing to label a sample of these tweets into three categories: those containing hate speech, only offensive language, and those with neither. We train a multi-class classifier to distinguish between these different categories. Close analysis of the predictions and the errors shows when we can reliably separate hate speech from other offensive language and when this differentiation is more difficult. We find that racist and homophobic tweets are more likely to be classified as hate speech but that sexist tweets are generally classified as offensive. Tweets without explicit hate keywords are also more difficult to classify.Comment: To appear in the Proceedings of ICWSM 2017. Please cite that versio

Cultural Values and Cross-cultural Video Consumption on YouTube

Video-sharing social media like YouTube provide access to diverse cultural products from all over the world, making it possible to test theories that the Web facilitates global cultural convergence. Drawing on a daily listing of YouTube's most popular videos across 58 countries, we investigate the consumption of popular videos in countries that differ in cultural values, language, gross domestic product, and Internet penetration rate. Although online social media facilitate global access to cultural products, we find this technological capability does not result in universal cultural convergence. Instead, consumption of popular videos in culturally different countries appears to be constrained by cultural values. Cross-cultural convergence is more advanced in cosmopolitan countries with cultural values that favor individualism and power inequality

Social dynamics from the bottom up:Agent-based models of social interaction

This article focuses on agent-based computational (ABC) modeling of social interaction. It begins with an overview of ABC modeling as a computational implementation of ‘methodological individualism’, the search for the microfoundations of social life in the actions of intentional agents. It then considers how the ABC method differs from an earlier generation of modeling approaches, including game theory, equation-based models of computer simulation (such as system dynamics), and multivariate linear models. It also discusses potential weaknesses of ABC modeling and proposes research strategies to address them. The article suggests that ABC modeling will lead to significant advances in the bottom-up approach to the study of social dynamics.</p