Web-conferencing as a viable method for group decision research

Studying group decision-making is challenging for multiple reasons. An important logistic difficulty is studying a sufficiently large number of groups, each with multiple participants. Assembling groups online could make this process easier and also provide access to group members more representative of real-world work groups than the sample of college students that typically comprise lab Face-to-Face (FtF) groups. The main goal of this paper is to compare the decisions of online groups to those of FtF groups. We did so in a study that manipulated gain/loss framing of a risky decision between groups and examined the decisions of both individual group members and groups. All of these dependent measures are compared for an online and an FtF sample. Our results suggest that web-conferencing can be a substitute for FtF interaction in group decision-making research, as we found no moderation effects of communication medium on individual or group decision outcome variables. The effects of medium that were found suggest that the use of online groups may be the preferred method for group research. To wit, discussions among the online groups were shorter, but generated a greater number of thought units, i.e., they made more efficient use of time

A Test of Rank-Dependent Utility in the Context of Ambiguity

Experimental investigations of non-expected utility have primarily concentrated on decision under risk (probability triangles). The literature suggests, however, that ambiguity is one of the main causes for deviations from expected utility (EU). This article investigates the descriptive performance of rank-dependent utility (RDU) in the context of choice under ambiguity. We use the axiomatic difference between RDU and EU to critically test RDU against EU. Surprisingly, the RDU model does not provide any descriptive improvement over EU. Our data suggest other framing factors that do provide descriptive improvements over EU

Dual microsporidial infection due to Vittaforma corneae and Encephalitozoon hellem in a patient with AIDS.

A 46-year-old human immunodeficiency virus-infected Swiss citizen living in Tanzania presented with respiratory, abdominal, and urogenital complaints. Microsporidial spores were isolated from urine and a sinunasal aspirate and were propagated in MRC-5 cell cultures. Western blot analysis and riboprinting identified the sinunasal isolate as Encephalitozoon hellem. Electron microscopic investigation of the urine isolate revealed spores with diplokaryotic nuclei and five to six isofilar coils of the polar tube and sporonts with two or three diplokarya. All stages were enveloped by two membranes, corresponding to a cisterna of host endoplasmic reticulum studded with ribosomes. These characteristics have been described for the genus Vittaforma. Western blot analysis of this isolate revealed a banding pattern identical to that of the Vittaforma corneae reference isolate. Part of the small subunit rRNA gene was amplified, sequenced (239 base pairs), and found to be identical to that of V. corneae. This is the second isolation of V. corneae and the first description of urinary tract infection due to V. corneae in a patient with AIDS

Comonotonic Independence: The Critical Test between Classical and Rank-Dependent Utility Theories

This article compares classical expected utility (EU) with the more general rank-dependent utility (RDU) models. The difference between the independence condition for preferences of EU and its comonotonic generalization in RDU provides the exact demarcation between EU and rank-dependent models. Other axiomatic differences are not essential. An experimental design is described that tests this difference between independence and comonotonic independence in its most basic form and is robust against violations of other assumptions that may confound the results, in particular the reduction principle and transitivity. It is well known that in the classical counterexamples to EU, comonotonic independence performs better than full-force independence. For our more general choice pairs, however, we find that comonotonic independence does not perform better. This is contrary to our prior expectation and suggests that rank-dependent models, in full generality, do not provide a descriptive improvement over EU. For rank-dependent models to have a future, submodels and choice situations need to be identified for which rank-dependence does contribute descriptively

Choice processes and their post-decisional consequences in morally conflicting decisions

Contains fulltext : 102372.pdf (publisher's version ) (Open Access)Morally challenging decisions tend to be perceived as difficult by decision makers and often lead to post-decisional worry or regret. To test potential causes of these consequences, we employed realistic, morally challenging scenarios with two conflicting choice options. In addition to respondents’ choices, we collected various ratings of choice options, decision-modes employed, as well as physiological arousal, assessed via skin conductance. Not surprisingly, option ratings predicted choice, such that the more positively rated option was chosen. However, respondents’ self-reported decision modes also independently predicted choice. We further found that simultaneously engaging in decision modes that predict opposing choices increased decision difficulty and post-decision worry. In some cases this was related to increased arousal. Results suggest that at least a portion of the negative consequences associated with morally challenging decisions can be attributed to conflict in the decision modes one engages in

Valuation of risky and uncertain choices

In this chapter, we describe how risk and ambiguity impact the value of choice options, how this impact can be modelled formally and how it is implemented in the brain. In particular, we give an overview of two distinct ways of how risky choice options can be decomposed – either into outcomes and probabilities as proposed in economics or into statistical moments of the probability distribution like mean, variance, or skewness, as proposed in finance theory. The components of either approach appear to be represented in common and, at least to some extent, in separate brain regions, which include the dopaminergic midbrain, striatum and the orbitofrontal cortex. Activity in different (prefrontal and striatal) brain regions also supports the distinction between decisions from experience, when knowledge about risk is learned through trial and error versus decisions from description, when it is described symbolically. The fact that the principal components of formal models from economics and finance theory and their behavioral versions that provide better descriptive fit are represented in the brain provides converging support for these models