Decisions, Groups and Networks
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Program

8 September

TimeTopic
09:00 - 09:30 Registration.
09:30 - 09:45 Welcome.
09:45 - 10:30 Network Topology, Truth and Value (Ulrike Hahn, Birbeck/MCMP)
10:30 - 11:15 Deliberating in a Prediction Market (Aidan Lyon, University of Maryland/MCMP)
11:15 - 11:45 Coffee
11:45 - 12:30 The Consistency Principle in Interpersonal Communication: Consequences of Preference Confirmation and Disconfirmation in Collective Decision-Making (Andreas Mojzisch, University of Hildesheim)
12:30 - 13:15 Anchoring in Deliberations (Stephan Hartmann, MCMP)
13:15 - 14:15 Lunch
14:15 - 15:00 Aggregation of Preferences in Unanimous Group Decision-Making (Martin Kocher, LMU)
15:00 - 15:45 Gender Differences in Networking at Work (Friederike Mengel, University of Essex/Maastricht University)
15:45 - 16:00 Coffee
16:00 - 16:45 Structural Power, Endowments, and Social Preferences in Networks: An Experiment in Coalition Formation (Bernhard Kittel, University of Vienna)
16:45 - 17:30 A Logic Approach to Lehrer, Wagner, and De Groot's Model of Opinion Dynamics in Social Networks (Jens Ulrik Hansen, Lund University)
18:30 Workshop Dinner Osterwaldgarten (Website)

9 September

TimeTopic
09:45 - 10:30 Multiple Committee Memberships in Parliaments: Causes, Network Topology, and Consequences (Paul Thurner, LMU)
10:30 - 11:15 Affinity Communities Among State Actors in the United Nations (Skyler Cranmer, UNC)
11:15 - 11:45 Coffee
11:45 - 12:30 "Let's Formalize Behavior": The Diffusion of Rational Choice Theory in American Social Sciences, 1944-1970. (Malte Doehne, Zeppelin University Friedrichshafen/Catherine Herfeld, MCMP)
12:30 - 13:15 Network Defense: Pruning and Closing the Network to Prevent Leakage of Strategic Knowledge to Rivals (Anja Tuschke, LMU)
13:15 - 14:15 Lunch

Abstracts

Affinity Communities Among State Actors in the United Nations

Skyler Cranmer

We construct new “affinity communities” to identify several policy preference profiles that underlie the interactions between states. We find these communities through an examination of a similarity network based on roll call votes of members of the United Nations. We apply community detection techniques from the machine learning literature to identify affinity communities that maximize out of sample predictions on hold out sets of votes. We examine the similarities and differences between these community identifications to measures of similarity used in the existing literature, such as Gartzke’s state affinity scores. Lastly, we examine the effects that community membership has on conflictual international behavior by including indicators of community identification in a temporal exponential random graph model (TERGM) of conflict. top

Network Topology, Truth and Value

Ulrike Hahn, Erik J. Olsson, Jens Ulrik Hansen

Both our beliefs and values are shaped by others. Much of what we believe is based on testimony, and what we value is influenced by other’s opinion. Our social networks thus have a crucial role in our determining both our beliefs and desires. In this context, we have been addressing the extent to which the patterns of connectivity within our social networks affect beliefs. Via computer simulations we examine the influence of network topology on what agent’s hold to be true.top

A Logic Approach to Lehrer, Wagner, and De Groot's Model of Opinion Dynamics in Social Networks

Jens Ulrik Hansen

In studying dynamic phenomena in social networks, such as opinion dynamics, social network analysis often makes use of simulations as an effective and insightful technique. However, logic can be a useful tool as well that may provide new and different insights. Using the model of opinion dynamics indecently developed by Lehrer and DeGroot as a case in point, I will show how logic can be used to reason about such models. More specifically, I will introduce a many-valued logic that borrows elements from Modal Logic, Hybrid Logic, and Fuzzy Logic to reason about Lehrer, Wagner and DeGroot’s model.top

Anchoring in Deliberations

Stephan Hartmann

Decision-making in not too large groups often proceeds through deliberation. This has the advantage that the group members can learn from each other and that, at the end, a consensus arises that everybody endorses. But deliberation also has a disadvantage: What consensus is reached often depends on the order in which the different group members speak. More specifically, the group member who speaks first will typically have the highest impact on the decision on which the group eventually agrees upon. She anchors the deliberation process. While the anchoring effect appears in real deliberating groups, we ask whether it also appears in groups whose members are truth-seeking and rational in the sense that they take the opinion of their fellow group members into account and update their beliefs according to plausible rules in each round of the deliberation. To address this question, we construct a formal model that is inspired by the Lehrer-Wagner model. Using this model, we study the anchoring effect in homogenous groups (i.e. groups whose members consider each other as epistemic peers), for which we provide analytical results, and for inhomogeneous groups, for which we run computer simulations. The paper is based on joint work with Soroush Rafiee Rad.top

"Let's Formalize Behavior": The Diffusion of Rational Choice Theory in American Social Sciences, 1944-1970.

Malte DoehneCatherine Herfeld

How are scientific theories developed and spread across scientific communities? We address those questions by applying social network analysis to a case of theory development and diffusion in the behavioral sciences. We conceptualize a scientific theory as an ‘innovation’ invented by one or more ‘innovators’, which becomes or does not become adopted by other actors in a social network. Our case study is what has commonly been labeled rational choice theory. We argue that rational choice theory was collaboratively developed and further modified between the 1940s and the 1960s by a very small group of outstanding scholars from distinct disciplines before it spread to the social and behavioral sciences at large. By analyzing in detail the distinct positions of those actors in the social network, we show that they occupied the role of ‘opinion leaders’ and of ‘pioneers’ for developing and adopting innovations, encouraging early adopters via imitation. Thereby, we shed light on the diffusion of scientific theories and make a more general case for the fruitfulness of social network analysis in history and philosophy of science.
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Structural Power, Endowments, and Social Preferences in Networks: An Experiment in Coalition Formation

Bernhard Kittel

In exchange theoretic models assuming self-interest utility maximization the structure of a network biases redistributive outcomes toward the powerful agents. Experiments have shown, however, that powerful agents do not always make use of their opportunities but instead redistribute towards disadvantaged agents. Currently, the rationale of this behavior is unclear. We design an experiment in which we, firstly, systematically vary the relative endowment of the middle player in a 3-line network and test whether the size of a redistributive tax rate favored by this player in the network varies with the endowment and whether this player is able to forge a coalition with one of the other players on that proposed tax rate. Secondly, we test whether the endowment effect interacts with social preferences in order to disentangle positional, social structural, and personal causes of redistributive taxation in experimental groups.top

Aggregation of Preferences in Unanimous Group Decision-Making

Martin Kocher

Evidence on the aggregation of preferences within groups or teams is very scarce. We look at cooperative preferences. Eliciting individual beliefs about others' contributions, asking for contribution proposals by team members before the team interaction, and adding an independent measure of cooperative preferences on the individual level in a laboratory social dilemma experiment allow us to analyze the mechanisms that aggregate cooperative attitudes into a final team decision. Our empirical results imply that teams are more willing to cooperate in social dilemmas than individuals at the outset, based on more optimistic expectations, particularly held by conditional cooperators. Thus, we report a reverse discontinuity effect.top

Deliberating in a Prediction Market

Aidan Lyon

It is well-known that deliberation, when appropriately structured and moderated, can improve group judgements, and therefore group decisions. It is also well-known that prediction markets have many advantages when it comes to forming group judgements. Deliberation groups and prediction markets are very different methods for determining group judgements, and they exhibit different beneficial properties. We may wonder, then, what happens if we were to combine them? Can we take what is best from a deliberation group and combine it with what is best from a prediction market? We present a series of computer simulations, in which we embed deliberation groups into prediction markets to study the effect that deliberation has on the market. We also study the effect that the prediction market has on the deliberation groups. The paper is co-authored with Eric Pacuit.top

Gender Differences in Networking at Work

Friederike Mengel

Gender differences in networking have been cited as one of the main reasons for gender earnings and promotion gaps. Despite this fact there is little evidence on whether such differences exist and how exactly they look like. We conduct an experiment to gain insight into these questions. In our experiment participants are matched in groups of 6 to perform a (gender-neutral) real effort task. After the task they receive information about their performance, their rank and the overall group performance, not about others’ performance. They can share information via forming links to other group members. After links are formed and information exchanged, one group member is selected to distribute the overall surplus among all group members. Treatments differ in how the ''decision-maker’’ is selected. In PERF the group member with the best performance in the task becomes decision-maker, in DESIG s/he is designated by the previous decision-maker and in LINKS the one with the highest number of links becomes decision-maker. We find evidence of gender and promotion gaps only in treatment LINKS. Women do not form less links than men, but their networks are less strategic than those of men.top

The Consistency Principle in Interpersonal Communication: Consequences of Preference Confirmation and Disconfirmation in Collective Decision-Making

Andreas Mojzisch

In my talk, I will propose a new model of interpersonal cognitive consistency in collective decision-making. Building on the mutual enhancement model (Wittenbaum et al., 1999), I will argue that group members evaluate one another more positively when they mention information confirming each other's decision preferences instead of information disconfirming these preferences. Moreover, I will hypothesize that group members who communicate information confirming each other's preferences receive positive feedback for doing so, which, in turn, leads group members to mention even more of this information. The results of three experiments provide converging support for this model (Mojzisch et al., 2014).top

Multiple Committee Memberships in Parliaments: Causes, Network Topology, and Consequences

Paul W. Thurner

Committees constitute the organizational infrastructure of parliaments. They mirror the division of labor in a legislature. Thus, information aggregation becomes a major challenge. The objective of this project is to put forward the idea of multiple committee memberships as a tool for strategic information exchange and for the coordination of legislative parties. We propose to investigate the causes and the consequences of the occurrence of multiple memberships in legislative committees. Using network analysis, we identify latent community structures of the organization of the European Parliament. We are able to show that the accumulation of committee assignments and the strategic position in this network are valuable investments leading to higher political returns of MPs.top

Network Defense: Pruning and Closing the Network to Prevent Leakage of Strategic Knowledge to Rivals

Anja Tuschke

We explore how firms protect themselves from the risks of knowledge spillover to indirectly connected rivals in a network of interorganizational ties. We argue that the safeguards to limit opportunistic behavior by direct partners in a dyad are insufficient to overcome extra-dyadic leakage risks. Instead, firms terminate or avoid ties that expose their knowledge to indirectly linked rivals (pruning) and embed themselves in dense networks (closing) to prevent strategic knowledge diffusion. Analyzing German board interlocks between 1990 and 2003, we find that firms are more likely to prune and close their networks as they accumulate strategic knowledge and as their partners increasingly generate indirect ties to competitors.