An avian urban morphotype: how the city environment shapes great tit morphology at different life stages

Urban Ecosystems - Urbanization is a worldwide phenomenon associated with tremendous modifications of natural habitats. Understanding how city dwelling species are affected by those changes is...     

The stability of exchange networks

Economic and sociological exchange theories predict divisions of exchange benefits given an assumed fixed network of exchange relations. Since network structure has been found to have a large impact on actors’ payoffs, actors have strong incentives for network change. We answer the question what happens to both the network structure and actor payoffs when myopic actors change their links in order to maximize their payoffs. We investigate the networks that are stable, the networks that are efficient or egalitarian with varying tie costs, and the occurrence of social dilemmas. Only few networks are stable over a wide range of tie costs, and all of them can be divided into two types: efficient networks consisting of only dyads and at most one isolate, and Pareto efficient and egalitarian cycles with an odd number of actors. Social dilemmas are observed in even-sized networks at low tie costs.     

Analyzing large scale exchange networks

Exchange theories or their implementations in algorithms have limited utility because they can be applied only to quite small networks. They cannot be applied to larger networks until that size limit is removed. Domain Analysis cuts networks into smaller pieces at the boundaries of strong power domains. Domain Analysis identifies strong power and breaks, and distinguishes domains that function exactly as they would were they free-standing, and components that do not. Support for the finding of breaks and the distinction between domains and components are obtained using both experimental data and simulations based on X-Net. To illustrate the use of Domain Analysis, it is applied to find the incidence of strong power in large exchange networks. The application shows that the incidence of strong power decreases as network density increases, and that strong power occurs only infrequently in dense networks. We conclude by calling for ever more general analytic procedures.     

Mothering,Fathering, and Externalizing Behavior in Toddler Boys

This study examined the effects of reported maternal and paternal support, psychological control, and spanking on externalizing behavior of toddler boys. Questionnaires were administered to both parents of 104 two‐parent families with a 3‐year‐old son. Both maternal and paternal psychological control was related to boys' externalizing behavior. Interaction effects were found, in that the association between maternal spanking and boys' externalizing behavior was stronger when levels of maternal support were high. High levels of paternal support strengthened the association between maternal support and boys' externalizing behaviors. Results suggest that the associations between specific parenting dimensions and children's externalizing behavior need to be considered within the context of other parenting dimensions that are displayed within the family.     

Unanticipated consequences of “humanitarian intervention”: The British campaign to abolish the slave trade, 1807–1900

Building on Robert Merton’s theory of unanticipated consequences of purposive action and Charles Tilly’s theory of error correction, the present article presents a stylized narrative about the British campaign to abolish the trading in African slaves, from its beginning in 1807 until the end of the nineteenth century. In the end, this campaign was largely successful, though it required error corrections that had extremely far-reaching consequences. The colonization of Africa was, to a certain extent, a second-degree unanticipated consequence. This case study suggests that three sorts of error correction can be distinguished, namely (a) measures that are taken to facilitate the effective implementation of the purposive action; (b) measures that are taken to minimize unintended consequences, after the purposive action has been carried out; and (c) new purposive actions that widen the objective and are more far-reaching than the original purposive action.     

Gratitude,indebtedness, and reciprocity: an extended replication of Bartlett & DeSteno (2006)

ABSTRACT

In a landmark study in 2006, Bartlett and DeSteno found that receiving help promoted reciprocal behavior and that this effect was mediated by gratitude. Recent research, however, suggested that indebtedness is more closely associated with reciprocation than gratitude. Therefore, we examined whether reciprocal behavior could (also) be attributed to indebtedness. Specifically, we attempted to replicate and extend Bartlett and DeSteno’s Study 1 by additionally including a measure of indebtedness. Surprisingly, the replication was not successful. We did not find support for the idea that receiving help promoted reciprocal behavior, and neither gratitude nor indebtedness was associated with reciprocal behavior. Finally, we call for attention that the extant literature may be inconclusive regarding the presumed prosocial effects of gratitude.     

Network public goods with asymmetric information about cooperation preferences and network degree

We propose a game theoretical model of one-shot network public goods formalizing the ‘closure argument’ that cooperation is more frequent in denser groups or networks. Equilibrium analyses show that (i) an ‘inefficiency problem’ exists: players all preferring mutual cooperation need not all cooperate; (ii) in dyads, groups and networks with degree independence, first order stochastic dominance shifts of the distribution of cooperation preferences or the degree distribution (weakly) increases cooperation, and (iii) the latter result does not hold for networks with degree dependence. Hence the closure argument always holds in networks satisfying degree independence but not in other networks.     

BETWEEN BROADCASTING POLITICAL MESSAGES AND INTERACTING WITH VOTERS

Politicians across Western democracies are increasingly adopting and experimenting with Twitter, particularly during election time. The purpose of this article is to investigate how candidates are using it during an election campaign. The aim is to create a typology of the various ways in which candidates behaved on Twitter. Our research, which included a content analysis of tweets (n?=?26,282) from all twittering Conservative, Labour and Liberal Democrat candidates (n?=?416) during the 2010 UK General Election campaign, focused on four aspects of tweets: type, interaction, function and topic. By examining candidates' twittering behaviour, the authors show that British politicians mainly used Twitter as a unidirectional form of communication. However, there were a group of candidates who used it to interact with voters by, for example, mobilizing, helping and consulting them, thus tapping into the potential Twitter offers for facilitating a closer relationship with citizens.     

NETWORKS AND SELECTION IN INTERNATIONAL MIGRATION TO SPAIN

We offer fresh evidence on the effect of migrant networks on two essential aspects of migration: (1) the total scale of migration and (2) the skill composition of migration. Our analysis is for the remarkable case of Spain, which experienced a full‐blown immigration boom from the mid‐1990s up to the Global Financial Crisis. To accommodate flexible substitution patterns across alternative migrant destinations, we use a three‐level nested multinomial logit model. We find a strong positive network effect on the scale of migration and a strong negative effect on the ratio of high‐skilled to low‐skilled migrants. Simplifying restrictions on the structure of cross‐destination substitutability are rejected by the data. (JEL F22, J61)