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There is an ongoing debate about whether the Internet is like a public sphere or an echo chamber. Among many forms of social media, Twitter is one of the most crucial online places for political debate. Most of the previous studies focus on the formal structure of the Twitter political field, such as its homophilic tendency, or otherwise limits the analysis to a few topics. In order to explore whether Twitter functions as an echo chamber in general, however, we have to investigate not only the structure but also the contents of Twitter's political field. Accordingly, we conducted both large-scale social network analysis and natural language processing. We firstly applied a community detection method to the reciprocal following network in Twitter and found five politically distinct communities in the field. We further examined dominant topics discussed therein by employing a topic model in analyzing the content of the tweets, and we found that a topic related to xenophobia is circulated solely in right-wing communities. To our knowledge, this is the first study to address echo chambers in Japanese Twitter political field and to examine the formal structure and the contents of tweets with the combination of large-scale social network analysis and natural language processing.

This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Highlights  A game-theoretical model of the emergence of an egalitarian society is considered.  In this model, social control against a potentially dominant individual plays a central role in the emergence.  A potentially despotic payoff structure, large group size, small cost of competition, and variation in the strength of individuals can promote the evolution of egalitarian behavior

There is a growing body of research that focuses on the supposedly close association between an individual's moral-emotional behavior and his/her political ideology. A prominent example is Haidt's "moral psychology," which claims that political liberals and conservatives draw on mutually different sets of moral foundations. However, this and other arguments, which have mostly been advanced in the social context of the United States, lack a comparative perspective. In this study, we examine these arguments in broader spatio-temporal settings by way of a comparative analysis of public deliberations in the U.S. and Japanese legislatures. More specifically, with the help of well-established moral-and emotional-word dictionaries, and employing advanced computational techniques for systematic data collection, we analyze a large volume of speech data that records floor debates over decades in the U.S. Congress and the Japanese Diet to derive longitudinal moral-emotional dynamics. We then use multilevel modeling to regress the derived moral-emotional patterns of legislative deliberations in each country on various covariates to locate possible drivers of these patterns. The results of these analyses reveal more qualified relationships between a moral-emotional framework and political ideology than preceding arguments have suggested, casting serious doubt on the widespread tendency in the literature to quickly rely on an ideological explanation. The findings suggest the need for a more comprehensive approach to handling moral-emotional phenomena in political science.

The Japanese Association for Mathematical Sociology celebrates its 30th anniversary this year. We describe longitudinal trends of Sociological Theory and Methods in thirty years by analyzing all the articles from total volume 1 (1986) to 58 (2015). We divide themes and methods by using topic models. As a result, we show that themes and methods transformed around year 2000. Moreover, both transformations seem to depend on each other.

There has been a growing body of study on the relationship between public/political discourse and its moral-emotional foundations. Most of the studies, however, have been confined to a single country's context, lacking cross-cultural perspectives. Taking a comparative perspective, we examined the emotional and moral structures of political and public discussion observed in the U.S. and Japan by employing extensive text data that cover these two countries. Specifically, we conducted dictionary-based sentiment and moral analyses of floor debate in the U.S. Congress and the Japanese Diet over a long period of time. The analyses revealed intriguing cross-national patterns in the moral-emotional framework employed in parliamentary deliberations, which cast doubt on some of the dominant arguments in the field, including, among others, J. Haidt's moral foundation hypothesis.

Political polarization in public space can seriously hamper the function and the integrity of contemporary democratic societies. In this paper, we propose a novel measure of such polarization, which, by way of simple topic modelling, quantifies differences in collective articulation of public agendas among relevant political actors. Unlike most other polarization measures, our measure allows cross-national comparison. Analyzing a large amount of speech records of legislative debate in the United States Congress and the Japanese Diet over a long period of time, we have reached two intriguing findings. First, on average, Japanese political actors are far more polarized in their issue articulation than their counterparts in the U.S., which is somewhat surprising given the recent notion of U.S. politics as highly polarized. Second, the polarization in each country shows its own temporal dynamics in response to a different set of factors. In Japan, structural factors such as the roles of the ruling party and the opposition often dominate such dynamics, whereas the U.S. legislature suffers from persistent ideological differences over particular issues between major political parties. The analysis confirms a strong influence of institutional differences on legislative debate in parliamentary democracies.

Most human societies conduct a high degree of division of labor based on occupation. However, determining the occupational field that should be allocated a scarce resource such as vaccine is a topic of debate, especially considering the COVID-19 situation. Though it is crucial that we understand and anticipate people’s judgments on resource allocation prioritization, quantifying the concept of occupation is a difficult task. In this study, we investigated how well people’s judgments on vaccination prioritization for different occupations could be modeled by quantifying their knowledge representation of occupations as word vectors in a vector space. The results showed that the model that quantified occupations as word vectors indicated high out-of-sample prediction accuracy, enabling us to explore the psychological dimension underlying the participants’ judgments. These results indicated that using word vectors for modeling human judgments about everyday concepts allowed prediction o...

Background The availability of large-scale and fine-grained aggregated mobility data has allowed researchers to observe the dynamics of social distancing behaviors at high spatial and temporal resolutions. Despite the increasing attention paid to this research agenda, limited studies have focused on the demographic factors related to mobility, and the dynamics of social distancing behaviors have not been fully investigated. Objective This study aims to assist in designing and implementing public health policies by exploring how social distancing behaviors varied among various demographic groups over time. Methods We combined several data sources, including mobile tracking mobility data and geographical statistics, to estimate the visiting population of entertainment venues across demographic groups, which can be considered the proxy of social distancing behaviors. Next, we used time series analysis methods to investigate how voluntary and policy-induced social distancing behaviors s...

Crowdfunding is a new funding method through which founders request small amounts of funding from a large number of people through an online platform. Crowdfunding facilitates a new type of social capital and exhibits a unique form of social dynamics, thus attracting the interest of sociologists and other social scientists. Previous studies have focused on social relationships in crowdfunding such as direct reciprocity and consider how they contribute to the success of funding. The social structure of crowdfunding, however, involves more complex social relationships and it may contribute to the success of a new venture or project in many ways. In this study, we focus on a specific type of triadic social structure, the buddy relation, which can be described as a relationship through which project founder x, who previously backed another founder z's project, receives financial backing from the other backers of z's project. We found that the buddy relation occurs significantly more often than randomly, concluding that this structure facilitates the gathering of financial backing and may contribute to the success of a crowdfunded project.

This paper proposes normative theory of "reciprocity-based" equality. It is constructed to be an alternative of "rightbased" equality theory. The theory is subsumed under three points below: 1 interactive/local, 2 other-regarded, 3 otheroriented responsibility. It is often assumed that reciprocity-principle is incompatible with distributive equality. I refute this conjecture and demonstrate that reciprocity can be compatible with distributive equality, especially on the idea of reciprocity as value.

Despite considerable scholarly attention on the institutional and normative aspects of development cooperation, its longitudinal dynamics unfolding at the global level have rarely been investigated. Focusing on aid, we examine the evolving global structure of development cooperation induced by aid flows in its entirety. Representing annual aid flows between donors and recipients from 1970 to 2013 as a series of networks, we apply hierarchical stochastic block models to extensive aid-flow data that cover not only the aid behavior of the major OECD donors but also that of other emerging donors, including China. Despite a considerable degree of external expansion and internal diversification of aid relations over the years, the analysis has uncovered a temporally persistent structure of aid networks. The latter comprises, on the one hand, a limited number of major donors with far-reaching resources and, on the other hand, a large number of mostly poor but globally well-connected recipi...

Trust has been considered the "cement" of a society and is much studied in sociology and other social sciences. Most studies, however, have neglected one important aspect of trust: it involves an act of forgiving and showing tolerance toward another's failure. In this study, we refer to this concept as "generous trust" and examine the conditions under which generous trust becomes a more viable option when compared to other types of trust. We investigate two settings. First, we introduce two types of uncertainties: uncertainty as to whether trustees have the intention to cooperate, and uncertainty as to whether trustees have enough competence to accomplish the entrusted tasks. Second, we examine the manner in which trust functions in a broader social context, one that involves matching and commitment processes. Since we expect generosity or forgiveness to work differently in the matching and commitment processes, we must differentiate trust strategies into generous trust in the matching process and that in the commitment process. Our analytical strategy is twofold. First, we analyze the "modified" trust game that incorporates the two types of uncertainties without the matching process. This simplified setting enables us to derive mathematical results using game theory, thereby giving basic insight into the trust mechanism. Second, we investigate socially embedded trust relationships in contexts involving the matching and commitment processes, using agent-based simulation. Results show that uncertainty about partner's intention and competence makes generous trust a viable option. In contrast, too much uncertainty undermines the possibility of generous trust. Furthermore, a strategy that is too generous cannot stand alone. Generosity should be accompanied with moderate punishment. As for socially embedded trust relationships, generosity functions differently in the matching process versus the commitment process. Indeed, these two types of generous trust coexist, and their coexistence enables a society to function well.

Background: The availability of large-scale and fine-grained aggregated mobility data has allowed researchers to observe the dynamics of social distancing behaviors at high spatial and temporal resolutions. Despite the increasing attention paid to this research agenda, limited studies have focused on the demographic factors related to mobility, and the dynamics of social distancing behaviors have not been fully investigated. Objective: This study aims to assist in designing and implementing public health policies by exploring how social distancing behaviors varied among various demographic groups over time. Methods: We combined several data sources, including mobile tracking mobility data and geographical statistics, to estimate the visiting population of entertainment venues across demographic groups, which can be considered the proxy of social distancing behaviors. Next, we used time series analysis methods to investigate how voluntary and policy-induced social distancing behaviors shifted over time across demographic groups. Results: Our findings demonstrate distinct patterns of social distancing behaviors and their dynamics across age groups. On the one hand, although entertainment venues' population comprises mainly individuals aged 20-40 years, a more significant proportion of the youth has adopted social distancing behaviors and complied with policy implementations compared to older age groups. From this perspective, the increasing contribution to infections by the youth should be more likely to be attributed to their number rather than their violation of social distancing behaviors. On the other hand, although risk perception and self-restriction recommendations can induce social distancing behaviors, their impact and effectiveness appear to be largely weakened during Japan's second state of emergency. Conclusions: This study provides a timely reference for policymakers about the current situation on how different demographic groups adopt social distancing behaviors over time. On the one hand, the age-dependent disparity requires more nuanced and targeted mitigation strategies to increase the intention of elderly individuals to adopt mobility restriction behaviors. On the other hand, considering that the effectiveness of policy implementations requesting social distancing behaviors appears to decline over time, in extreme cases, the government should consider imposing stricter social distancing interventions, as they are necessary to promote social distancing behaviors and mitigate the transmission of COVID-19.

Political polarization in public space can seriously hamper the function and the integrity of contemporary democratic societies. In this paper, we propose a novel measure of such polarization, which, by way of simple topic modelling, quantifies differences in collective articulation of public agendas among relevant political actors. Unlike most other polarization measures, our measure allows cross-national comparison. Analyzing a large amount of speech records of legislative debate in the United States Congress and the Japanese Diet over a long period of time, we have reached two intriguing findings. First, on average, Japanese political actors are far more polarized in their issue articulation than their counterparts in the U.S., which is somewhat surprising given the recent notion of U.S. politics as highly polarized. Second, the polarization in each country shows its own temporal dynamics in response to a different set of factors. In Japan, structural factors such as the roles of the ruling party and the opposition often dominate such dynamics, whereas the U.S. legislature suffers from persistent ideological differences over particular issues between major political parties. The analysis confirms a strong influence of institutional differences on legislative debate in parliamentary democracies.