Victorious and Hierarchical: Past Performance as a Determinant of Team Hierarchical Differentiation

Hierarchies emerge as collectives attempt to organize themselves toward successful performance. Consequently, research has focused on how team hierarchies affect performance. We extend existing models of the hierarchy-performance relationship by adopting an alternative: Performance is not only an output of hierarchy but also a critical input, as teams’ hierarchical differentiation may vary based on whether they are succeeding. Integrating research on exploitation and exploration with work on group attributions, we argue that teams engage in exploitation by committing to what they attribute as the cause of their performance success. Specifically, collectives tend to attribute their success to individuals who wielded greater influence within the team; these individuals are consequently granted relatively higher levels of influence, leading to a higher degree of hierarchy. We additionally suggest that the tendency to attribute, and therefore grant more influence, to members believed to be the cause of success is stronger for teams previously higher (versus lower) in hierarchy, as a higher degree of hierarchical differentiation provides clarity as to which members had a greater impact on the team outcome. We test our hypotheses experimentally with teams engaging in an online judgement task and observationally with teams from the National Basketball Association. Our work makes two primary contributions: (a) altering existing hierarchy-performance models by highlighting performance as both an input and output to hierarchy and (b) extending research on the dynamics of hierarchy beyond individual rank changes toward examining what factors increase or decrease hierarchical differentiation of the team as a whole.

Male dominance relationships in an extremely large chimpanzee community at Ngogo, Kibale National Park, Uganda

Male dominance hierarchies occur in many group-living primates and some non-primate mammals. Variation in aspects of agonistic relationships such as how many dyads show bidirectionality in aggression leads to variation in dominance hierarchies along a continuum from egalitarian (relatively small agonistic power differences between adjacently-ranked individuals, shallow hierarchies) to despotic (relatively large differences, steep hierarchies). Ranks usually depend mostly or entirely on individual characteristics that influence fighting ability (e.g., body size) and show inverse-U shaped relationships to age. However, coalitionary support sometimes also influences ranks. Chimpanzees (Pan troglodytes) form multi-male, multi-female communities within which males compete for status. Males typically form dominance hierarchies, and data from multiple study show that rank is positively related to paternity success. Males also often form coalitions and some dyads form long-term alliances. Effective coalitionary support can help individuals improve and maintain their ranks, and some evidence supports the hypothesis that coalitionary aggression generally, and the positions that males hold in coalitions networks specifically, influences paternity success. Hierarchy steepness varies among communities and within communities over time; variation in the number of prime-aged males per community is a likely source of this variation. Long-term data from an extremely large chimpanzee community with unusually many males, at Ngogo, Kibale National Park, Uganda, are largely consistent with previous analyses of male chimpanzee dominance hierarchies, but show several notable contrasts. Males at Ngogo formed significantly linear hierarchies and hierarchy steepness was greater than expected if the outcomes of agonistic interactions were random. However, variation in steepness did not show the significant inverse relationship to the number of “prime-aged” males documented for other chimpanzee communities and average steepness was high given the large number of males. Ranks showed an inverse-U shaped relationship to age, although individual rank trajectories varied considerably, but males attained their highest lifetime ranks at later ages and maintained relatively high ranks to later ages than those at other chimpanzee research sites. Two measures of coalition networks, strength and Bonacich power, showed significant positive relationships with male ranks. Strength is the rate at which males joined coalitions. Bonacich power is a measure of network centrality that assesses a male’s relational power, or influence (Bonacich, 1987): a male with high Bonacich power formed coalitions with relatively many other males who were also central in the coalition network, i.e., he was strongly connected to powerful others. On average, males also attained maximum values for these and other network measures relatively late and maintained relatively high values to relatively late ages. High coalition network strength, Bonacich power, and eigenvector centrality early in adulthood were associated with high peak ranks at later ages. However, the direction of causality between participation in coalition networks and ranks is not yet clear, and the effects of body size on dominance ranks and individual rank trajectories remains to be explored. Ngogo is a favourable habitat for chimpanzees and survivorship there is unusually high; this presumably facilitates the ability of males to maintain high competitive ability longer than at other sites and shifts rank trajectories toward older ages and leads to relatively steep hierarchies despite the fact that many male dyads have similar competitive ability. Future work will assess the impact of coalitions on dominance relationships in more detail and the relationship of coalitionary aggression to paternity success.

The Short Questionnaire to Assess Health-Enhancing (SQUASH) Physical Activity in Adolescents: A Validation Using Doubly Labeled Water

Background:Accurate assessment of physical activity energy expenditure (PAEE) among adolescents is important for surveillance, evaluating interventions, and understanding the relation between energy balance and normal physiological and behavioral growth and development. The purpose of this study was to examine the validity of the Short Questionnaire to Assess Health-Enhancing Physical Activity (SQUASH)13 for measuring PAEE among adolescents.Methods:The participants were seventeen adolescents (9 females; Mean age = 17.53; SD = 0.62). Energy expenditure was measured during a 9-day period with doubly labeled water (DLW). The SQUASH was self-administered on the morning of the 10th day and assessed commuting activities, leisure time activities, household activities, and activities at work and school over the previous 9 days.Results:A Bland-Altman plot indicated that the SQUASH underestimated PAEE compared with DLW by a mean difference of 126 kcal·d−1 (95% limits of agreement: –1,207 to 1,459 kcal·d−1), representative of a 10% underestimation. The Spearman rank order correlation coefficient showed there was a significant association between the SQUASH and DLW (r = .50, P = .04), for estimating PAEE.Conclusion:When using a sample of highly active adolescents, the SQUASH is a valid self-report tool for measuring PAEE at the group and individual rank order level.

Analysis of agonistic interactions between sows with different rank position during mixing

Ninety-six sows in twelve groups of eight sows were continuously video-observed during 48 hours after weaning and mixing. The occurrence and the outcome of all agonistic interactions (AI) were recorded and data of wins and defeats were transformed into a 8 × 8 (winner-loser) matrix. Aggressor and receiver of the attacks and fights in the dyads have been determined and the rank index for each sow was calculated leading to the individual rank place RP (1 to 8) and to the classifying into high ranking (HRS: RP 1 to 4) and low ranking sows (LRS: RP 5 to 8). Based on a total number of 2 414 AI dominant sows with RP=1 initiated 94.3 % of the AI they were involved in and were the receiver in 5.7 % of the AI. In contrast, every fourth AI was orientated towards the subdominant sow with RP=8. The sows with RP 7 or 8 were the receivers in nearly half of all AI (44.9 %). Fights occurred more frequently between sows with a low rank place difference. More than 60 % of the attacks and more than 40 % of the fights were initiated from high ranking sows towards low ranking sows even though 28.6 % was the estimated value for those dyads. In only 2 % of the attacks and 18.8 % of the fights LRS engaged HRS which means that HRS usually react with a counter-attack when being attacked by a LRS.

DETERMINING AGGREGATE CRITERIA WEIGHTS FROM CRITERIA RANKINGS BY A GROUP OF DECISION MAKERS

In this paper, we present an empirical methodology to determine aggregate numerical criteria weights from group ordinal ranks of multiple decision criteria. Assuming that such ordinal ranks are obtained from several decision makers, aggregation procedures are proposed to combine individual rank inputs into group criteria weights. In this process, we use previous empirical results for an individual decision maker, in which a simple function provides the weight for each criterion as a function of its rank and the total number of criteria. Using a set of experiments, weight aggregation procedures are proposed and empirically compared for two cases: (i) when all the decision makers rank the same set of criteria, and (ii) when they rank different subsets of criteria. The proposed methodology can be used to determine relative weights for any set of criteria, given only criteria ranks provided by several decision makers.