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A key benefit of sociality is a reduction in predation risk. Cohesive group behaviour and rapid collective decision making are essential for reducing predation risk in groups. Parasite infection might reduce an individuals’ grouping behaviours and thereby change the behaviour of the group as a whole. To investigate the relationship between parasite infection and grouping behaviours, we studied groups of three-spined sticklebacks, Gasterosteus aculeatus, varying the number of individuals experimentally infected with the cestode Schistocephalus solidus. We studied groups of six sticklebacks containing 0, 2, 3, 4 or 6 infected individuals before and after a simulated bird attack. We predicted that infected individuals would have reduced shoaling and swimming speed and that the presence of infected individuals within a group would reduce group cohesion and speed. Uninfected fish increased shoaling and reduced swimming speed more than infected fish after the bird attack. In groups containing both infected and uninfected fish, the group behaviours were dominated by the more frequent character (uninfected versus infected). Interestingly, groups with equal numbers of uninfected and infected fish showed the least shoaling and had the lowest swimming speeds, suggesting that these groups failed to generate a majority and therefore displayed signs of indecisiveness by reducing their swimming speed the most. Our results provide evidence for a negative effect of infection on a group’s shoaling behaviour, thereby potentially deteriorating collective decision making. The presence of infected individuals might thus have far-reaching consequences in natural populations under predation risk.

This paper investigates experimentally how a group's structure affects its ethical behavior towards a passive outsider. We analyze one vertical and two horizontal structures (one requiring consensus, one implementing a compromise by averaging proposals). We also control for internal communication. The data support our main predictions: (1) horizontal, averaging structures are more ethical than vertical structures (where subordinates do not feel responsible) and than consensual structures (where responsibility is dynamically diffused); (2) communication makes vertical structures more ethical (subordinates with voice feel responsible); (3) with communication, vertical structures are more ethical than consensual structures (where in-group bias hurts the outsider). (JEL C92, D23, L21, M14)

Combinatorial auctions have been studied analytically for several years, but only limited experimental results are available for auctions with more than 10 items. We investigate the Hierarchical Package Bidding auction (HPB), the Combinatorial Clock auction (CC), and one pseudo-dual price auction (PDP) experimentally, as all these formats were used or suggested for high-stakes spectrum auctions. We want to understand the impact that different auction formats have on bidder behavior and allocative efficiency. Interestingly, we find that the main source of inefficiency in all formats is the bidders’ preselection of packages, rather than their strategies or auction rules; bidders mostly preselect a small number of packages of interest early in the auction. CC achieves high efficiency and revenue in all experiments, but HPB yields similar results even in value models, where hierarchical pre-packaging is difficult. Due to their influence on the decision of the US Federal Communications Commission, we intentionally repeated a set of experiments conducted by Goeree and Holt (GH) [Games and Economic Behavior 70:146–169, 2010 ], and find similar aggregate results. In addition, we analyze the CC auction and find that this mechanism has advantages in environments where the auctioneers’ hierarchy does not fit the bidders’ preferences well. In addition to the value models with global synergies in GH, we used value models where bidders have local synergies, which play a significant role in spectrum auctions in the field and lead to different results.

The theory of collective motion and the study of animal social networks have, each individually, received much attention. Currently, most models of collective motion do not consider social network structure. The implications for considering collective motion and social networks together are likely to be important. Social networks could determine how populations move in, split up into and form separate groups (social networks affecting collective motion). Conversely, collective movement could change the structure of social networks by creating social ties that did not exist previously and maintaining existing ties (collective motion affecting social networks). Thus, there is a need to combine the two areas of research and examine the relationship between network structure and collective motion. Here, we review different modelling approaches that combine social network structures and collective motion. Although many of these models have not been developed with ecology in mind, they present a current context in which a biologically relevant theory can be developed. We argue that future models in ecology should take inspiration from empirical observations and consider different mechanisms of how social preferences could be expressed in collectively moving animal groups.

Purpose This paper aims to investigate the interaction of the relationships between group behaviour, group process and learning outcomes in online executive education. Design/methodology/approach A systematic review of literature in the relevant conceptual domains is performed. Findings A framework is proposed from the systematic review and proposes a dynamic classroom environment where instructor capability interacts with group process and behaviour to generate new learning outcomes. The impact of institutional context and technology infrastructure are highlighted as drivers of both the classroom and instructor effectiveness. Research limitations/implications The systematic review highlights several future research trajectories posing the questions: How disruptive innovation impacts on instructor capability development? How alternative theories explain the routines underpinning instructor capability? What is the role of external partners in the development of learning in context? What is the nature of instructor innovation capability? and How does instructor technology capability impact on learning outcomes? Practical implications Human resource development practitioners are presented with insights as to their existing and potential future roles in enhancing group behaviour, process and learning outcomes in executive classrooms impacted by technological change. The subsequent potential for practitioner enabled learning innovation is highlighted. Originality/value This paper contributes to contemporary debates regarding the interaction of emerging technologies and the executive online classroom, specifically focusing on the area of group behaviour process and learning.

Economics has devoted little attention to whether the type of decision maker matters for economic decisions. However, many important decisions like those on monetary policy or a company's business strategy are made by (small) groups rather than an individual. We compare behaviour of individuals and small groups in an experimental beauty-contest game. Our findings suggest that groups are not smarter decision makers per se but that they learn faster than individuals. When individuals compete against groups, the latter significantly outperform the former in terms of payoff.

Virtue-based research in business ethics has increased over the last two decades, but most of the research has focused on the actions of an individual person. In this article, we examine the associations among team-level virtues using data from two studies. Specifically, we investigate whether transparency (usually thought to be an organizational-or collective-level construct), behavioral integrity (usually thought to be an individuallevel construct), and trust (usually thought to be an individual-level construct) can be conceptualized and operate at the team level of analysis and, if so, what their relationships are to team performance. Using Partial Least Squares (PLS) analysis, we found in both studies that team transparency was positively related to team behavioral integrity, which in turn was positively related to team trust. We also found evidence of a positive relationship between team trust and team performance. Implications of these findings for future teams and ethics research are discussed.

Plant photosynthate fuels carbon-limited microbial growth and activity, resulting in increased rhizosphere nitrogen (N) mineralization. Most soil organic nitrogen is macromolecular (chitin, protein, nucleotides); enzymatic depolymerization is likely rate limiting for plant nitrogen accumulation. Analyzing Avena (wild oat) planted in microcosms containing sieved field soil, we observed increased rhizosphere chitinase and protease-specific activities, bacterial cell densities, and dissolved organic nitrogen (DON) compared with bulk soil. Low-molecular-weight (MW) DON (<3000 Da) was undetectable in bulk soil but comprised 15% of rhizosphere DON. Extracellular enzyme production in many bacteria requires quorum sensing (QS), cell-density-dependent group behavior. Because proteobacteria are considered major rhizosphere colonizers, we assayed the proteobacterial QS signals N-acyl-homoserine lactones (AHLs), which were significantly increased in the rhizosphere. To investigate the linkage between soil signaling and nitrogen cycling, we characterized 533 bacterial isolates from Avena rhizosphere: 24% had chitinase or protease activity and AHL production; disruption of QS in seven of eight isolates disrupted enzyme activity. Many Alphaproteobacteria were newly found with QS-controlled extracellular enzyme activity. Enhanced specific activities of nitrogen-cycling enzymes accompanied by bacterial density-dependent behaviors in rhizosphere soil gives rise to the hypothesis that QS could be a control point in the complex process of rhizosphere nitrogen mineralization.

A fundamental debate in social sciences concerns how individual judgments and choices, resulting from psychological mechanisms, are manifested in collective economic behavior. Economists emphasize the capacity of markets to aggregate information distributed among traders into rational equilibrium prices. However, psychologists have identified pervasive and systematic biases in individual judgment that they generally assume will affect collective behavior. In particular, recent studies have found that judged likelihoods of possible events vary systematically with the way the entire event space is partitioned, with probabilities of each of N partitioned events biased toward 1/N. Thus, combining events into a common partition lowers perceived probability, and unpacking events into separate partitions increases their perceived probability. We look for evidence of such bias in various prediction markets, in which prices can be interpreted as probabilities of upcoming events. In two highly controlled experimental studies, we find clear evidence of partition dependence in a 2-h laboratory experiment and a field experiment on National Basketball Association (NBA) and Federation Internationale de Football Association (FIFA World Cup) sports events spanning several weeks. We also find evidence consistent with partition dependence in nonexperimental field data from prediction markets for economic derivatives (guessing the values of important macroeconomic statistics) and horse races. Results in any one of the studies might be explained by a specialized alternative theory, but no alternative theories can explain the results of all four studies. We conclude that psychological biases in individual judgment can affect market prices, and understanding those effects requires combining a variety of methods from psychology and economics.