Contest Behaviour Research Articles

Adult sex ratio influences courtship behaviour, contest behaviour and breeding success in Onthophagus taurus

Adult sex ratio influences courtship behaviour, contest behaviour and breeding success in Onthophagus taurus

Tractable Binary Contests

Much of the work on multi-agent contests is focused on determining the equilibrium behavior of contestants. This capability is essential for the principal for choosing the optimal parameters for the contest (e.g., prize amount). As it turns out, many contests exhibit not one, but many possible equilibria, hence precluding contest design optimization and contestants’ behavior prediction. In this article, we examine a variation of the classic contest that alleviates this problem by having contestants make the decisions sequentially rather than in parallel. We study this model in the setting of a binary contest , wherein contestants only choose whether or not to participate, while their performance level is exogenously set. We show that by switching to the sequential mechanism not only does there emerge a unique equilibrium behavior, but also that the principal can design this behavior to be as good, and, at times, better, than any pure-strategy equilibrium of the parallel setting (assuming the principal’s profit is either the maximum performance or the sum of performances). We also show that in the sequential setting, the optimal prize, which is inherently a continuous parameter, can be effectively computed and reduced to a set of discrete values to be evaluated. The theoretical analysis is complemented by comprehensive experiments with people over Amazon Mechanical Turk. Here, we find that the modified mechanism offers great benefit for the principal in terms of an increased over-participation in the contest (compared to theoretical expectations). The effect on the principal average profit, however, depends on its goal in the contest—when benefiting from the maximum performance the modified mechanism results in increased average profit, while when benefiting from the sum of performances, it is preferred to stay with the original (parallel) contest.

All politics are national: Partisan defection in national and subnational elections

AbstractObjectiveWhile they were once viewed as largely local or candidate‐centered contests, recent American elections have come to be dominated by national forces such as presidential politics and partisanship. Prior research on voter behavior in this new era of nationalized politics, however, has largely focused on more high‐profile contests and has not examined voter decision making across multiple levels of government.MethodsOur study uses cross‐sectional (2006–2020) survey data from the Cooperative Election Study to explore the determinants of partisan loyalty and defection across both national and subnational American elections.ResultsWe find consistent evidence that citizens increasingly rely upon national forces—specifically partisan‐ideological sorting and presidential approval—to make decisions about candidates up and down the ballot. We also find mixed evidence that evaluations of the national economy inform defection behavior.ConclusionThese findings indicate that the national political forces shape voter behavior in national and subnational contests in effectively identical ways. Thus, the evidence supports the notion that all (electoral) politics are now national.

Colony-level aggression escalates with the value of food resources

BackgroundTheory predicts that the level of escalation in animal contests is associated with the value of the contested resource. This fundamental prediction has been empirically confirmed by studies of dyadic contests but has not been tested experimentally in the collective context of group-living animals. Here, we used the Australian meat ant Iridomyrmex purpureus as a model and employed a novel field experimental manipulation of the value of food that removes the potentially confounding effects of nutritional status of the competing individual workers. We draw on insights from the Geometric Framework for nutrition to investigate whether group contests between neighbouring colonies escalate according to the value to the colony of a contested food resource.ResultsFirst, we show that colonies of I. purpureus value protein according to their past nutritional intake, deploying more foragers to collect protein if their previous diet had been supplemented with carbohydrate rather than with protein. Using this insight, we show that colonies contesting more highly valued food escalated the contest, by deploying more workers and engaging in lethal ‘grappling’ behaviour.ConclusionOur data confirm that a key prediction of contest theory, initially intended for dyadic contests, is similarly applicable to group contests. Specifically, we demonstrate, through a novel experimental procedure, that the contest behaviour of individual workers reflects the nutritional requirements of the colony, rather than that of individual workers.

Modelling animal contests based on spatio-temporal dynamics.

We present a general theoretical model for the spatio-temporal dynamics of animal contests. Inspired by interactions between physical particles, the model is formulated in terms of effective interaction potentials, which map typical elements of contest behaviour into empirically verifiable rules of contestant motion. This allows us to simulate the observable dynamics of contests in various realistic scenarios, notably in dyadic contests over a localized resource. Assessment strategies previously formulated in game-theoretic models, as well as the effects of fighting costs, can be described as variations in our model's parameters. Furthermore, the trends of contest duration associated with these assessment strategies can be derived and understood within the model. Detailed description of the contestants' motion enables the exploration of spatio-temporal properties of asymmetric contests, such as the emergence of chase dynamics. Overall, our framework aims to bridge the growing gap between empirical capabilities and theory in this widespread aspect of animal behaviour.

Game theory in biology: 50 years and onwards.

Game theory in biology gained prominence 50 years ago, when Maynard Smith & Price formulated the concept of an evolutionarily stable strategy (ESS). Their aim was to explain why conflicts between animals of the same species usually are of a 'limited war' type, not causing serious injury. They emphasized that game theory is an alternative to previous ideas about group selection, which were used by ethologists to explain limited aggression. Subsequently, the ESS concept was applied to many phenomena with frequency dependence in the evolutionary success of strategies, including sex allocation, alternative mating types, contest behaviour and signalling, cooperation, and parental care. Both the analyses of signalling and cooperation were inspired by similar problems in economics and attracted much attention in biology. Here we give a perspective on which of the ambitions in the field have been achieved, with a focus on contest behaviour and cooperation. We evaluate whether the game-theoretical study of the evolution of cooperation has measured up to expectations in explaining the behaviour of non-human animals. We also point to potentially fruitful directions for the field, and emphasize the importance of incorporating realistic behavioural mechanisms into models. This article is part of the theme issue 'Half a century of evolutionary games: a synthesis of theory, application and future directions'.

Feedback types and users’ behavior in online innovation contests: Evidence of two underlying mechanisms

Online innovation contests (OIC) provide companies, via a dedicated community, an important means to access remote knowledge and ideas of users and thereby a creative playground for fueling innovation. Our literature review shows that our understanding of the impact of diverse types of feedback on user participation, especially continued participation, and success in OIC is at a nascent stage. The present study therefore seeks to examine why and how different types of feedback influence users’ behavior in OIC, and the detailed mechanisms underlying such influences. While our results do not show a significant relationship between receiving peer dynamic feedback and user success, we find that receiving sponsor static feedback in users’ first submission is positively associated with their continued participation in OIC. Also, when compared to peer dynamic feedback, sponsor static feedback has a stronger effect on users’ continued participation. Our goal is to confer a holistic picture of how the timing, source, and form of feedback shape user continuous participation and success in OIC.

Відносини по лінії центр-периферія в Україні: ресурси підвищення стійкості держави

This article identifies key factors that helped reducing the conflict potential in centre-periphery relations in Ukraine and enabled their contribution to state resilience in 2022–2023. The analytical framework is based on rational choice institutionalism and cleavage theory. The article argues that the conflict potential of center-periphery relations in the past was triggered by political competition between key central political actors for a subordination of subnational political actors, in order to strengthen their own positions in the Center. The article specifies two factors that helped reducing the conflict potential of centre-periphery relations and enabled a positive input from them into Ukraine’s state resilience in 2022–2023. The first factor is an institutional one, i. e. the decentralization reform (2014–2020), which strengthened duties and resources of local self-government rather than regional administrations. The second factor is a non-institutional one; it is a „nationalization” of electoral behaviour in democratic contests that led to the emergence of a dominant central political actor and turn away from competitive struggles between central political actors with the help of subnational actors. A shift in the pattern of center-periphery relations was visible in changing interaction of the dominant central political actor with subnational actors during the 2020 regional elections. Still, the article acknowledges that such institutionalized and non-institutionalized changes cannot automatically neutralize clan or oligarchic structures at the local level. Finally, the article identified three types of concrete contributions of Ukraine's new center-periphery relations to increasing state resilience in 2022–2023. They happened via enabling the input of local self-government into territorial defense, the support of internally displaced persons, and Ukraine’s recovery from the Russia’s war.

Weapon performance and contest assessment strategies of the cavitating snaps in snapping shrimp

AbstractAnimals compete in contests over limited resources. Contestants forfeit once they ascertain that their opponent has greater resource‐holding potential (RHP; mutual assessment) or once they reach a threshold of costs (self‐assessment). Functional scaling studies of contest behaviour performance can inform how assessment signals, offensive capacity and endurance scale with RHP and thereby elucidate the mechanisms through which each of these assessment types operates.Here, we performed behavioural contest analyses to determine the assessment strategies used in snapping shrimp (Alpheus heterochaelis) contests. Then, we used biomechanical measurements of a common contest behaviour to inform how assessment might operate. We were specifically interested in the snapping behaviour during which snapping shrimp fire imploding cavitation bubbles—hereafter, ‘snaps’—at their opponents.We showed thatA. heterochaelisuse mutual assessment early in contests. Then, when they fire snaps, they switch to cumulative assessment—a type of self‐assessment where contestants endure costs from their own behaviours (e.g. energy) and their opponent's (e.g. injury).Because larger individuals tend to win contests, we then tested how the maximum performance and endurance of snaps scaled with size. We measured the average angular velocity of the snapping dactyl, cavitation bubble duration and pressure of snaps as metrics of performance. We measured 10 snaps per individual (n = 76 individuals). From this series of 10 snaps, we calculated the maximum of each metric as the maximum performance and the attrition of each metric over the course of 10 snaps as a measure of endurance. Maximum performance increased with size, but endurance did not.This suggests that cumulative assessment in snapping shrimp is driven by opponent‐imposed costs. Our results are not consistent with self‐assessment based on endurance; however, the experiment could not fully replicate the quick succession of snaps fired in real contests. Future experiments should better replicate the rapid firing of snaps to test if endurance matters in a more ecologically relevant context.Our framework of integrating biomechanics and behavioural ecology provides a pathway to identify precise mechanisms of contest assessment and animal behaviour more broadly.Read the freePlain Language Summaryfor this article on the Journal blog.

Biocontrol implications of multiparasitism by Trissolcus mitsukurii and Trissolcus japonicus on the invasive brown marmorated stink bug

AbstractThe egg parasitoids Trissolcus japonicus (Ashmead) and Trissolcus mitsukurii (Ashmead) (Hymenoptera: Scelionidae) are the most effective biocontrol agents of the invasive agricultural pest Halyomorpha halys (Stål) (Heteroptera: Pentatomidae) in its native range (east Asia). Trissolcus japonicus and T. mitsukurii are sympatric in the native areas. In northern Italy, where H. halys is a major pest of fruit orchards, adventive populations of both species are spreading, and T. japonicus is artificially released under a classical biocontrol program against H. halys. This laboratory study aimed to assess the outcome of competition when both species share the same resource and possible implications for the biological control of the invasive stink bug. Egg masses of H. halys were offered to each parasitoid after previous parasitization by the other species. Parasitoid behaviour, number of ovipositions, and successfully developed parasitoids were recorded. Additionally, contest behaviour was assessed when both species were released simultaneously on the same egg mass. Results showed that both T. japonicus and T. mitsukurii were able to parasitize an egg mass already parasitized by the other species. Competition occurred within the host eggs and each species outperformed the other when it was the first to oviposit. Importantly, the overall contribution to H. halys mortality was not affected by the interaction between parasitoids, as non‐parasitized eggs were 4–6% in the absence of competition and <8% in its presence, respectively. When simultaneously released on the egg mass, T. mitsukurii was more aggressive, engaging in chase‐off events in 71% of cases compared to 50% of T. japonicus.

Sabotage in dynamic tournaments with heterogeneous contestants: Evidence from European football

This paper analyses how sabotage, measured as the number of fouls and yellow and red cards, is affected by the relative performance of and asymmetries between teams, determined based on score margin and the odds gap between one team and its opponent. By applying detailed controls for within-match dynamics and differences in team quality, we first observe that badly losing favourites are more willing than losing underdogs to increase their unsporting behaviour in heterogeneous contests. There are more yellow cards and fouls as the game progresses. We further find that most sabotage (yellow cards) can be observed when the (absolute) goal difference is equal to 1. Teams decrease their level of sabotage (fouls) by increasing the number of goals of lead or trail. In addition, weaker teams have an incentive to engage in more unfair and destructive strategies, such as committing more fouls, including those penalized with yellow cards. However, the incidence of red cards is not influenced by the score margin or strength gap.

Fighting over defense chemicals disrupts mating behavior.

Studies on intraspecific contest behavior predominantly focus on contests between individuals of the same sex, however contest behavior is also expected to occur between individuals of the opposite sex including possible mates. Here we investigate potential trade-offs between mating and fighting behavior in the turnip sawfly (Athalia rosae). Adults of this species collect chemical defense compounds (clerodanoids) directly from plants but also indirectly by nibbling on conspecifics that have already obtained clerodanoids, a highly aggressive behavioral interaction. An A. rosae individual without clerodanoids may therefore be the potential mate or attacker of an individual of the opposite sex that has gained clerodanoids. To test the effect of clerodanoids on agonistic and mating behavior we paired females and males with or without clerodanoid access in a two-way factorial design. We show that asymmetrical clerodanoid acquisition between female-male pairs causes an increase in agonistic nibbling behavior, irrespective of sex, and moreover that conflict between individuals delays mating behavior. Our study highlights the importance of investigating agonistic intersex interactions, which can occur when adults are able to acquire valuable non-reproductive resources from a potential partner.

Spatiotemporal dynamics of animal contests arise from effective forces between contestants

Competition among animals for resources, notably food, territories, and mates, is ubiquitous at all scales of life. This competition is often resolved through contests among individuals, which are commonly understood according to their outcomes and in particular, how these outcomes depend on decision-making by the contestants. Because they are restricted to end-point predictions, these approaches cannot predict real-time or real-space dynamics of animal contest behavior. This limitation can be overcome by studying systems that feature typical contest behavior while being simple enough to track and model. Here, we propose to use such systems to construct a theoretical framework that describes real-time movements and behaviors of animal contestants. We study the spatiotemporal dynamics of contests in an orb-weaving spider, in which all the common elements of animal contests play out. The confined arena of the web, on which interactions are dominated by vibratory cues in a two-dimensional space, simplifies the analysis of interagent interactions. We ask whether these seemingly complex decision-makers can be modeled as interacting active particles responding only to effective forces of attraction and repulsion due to their interactions. By analyzing the emergent dynamics of "contestant particles," we provide mechanistic explanations for real-time dynamical aspects of animal contests, thereby explaining competitive advantages of larger competitors and demonstrating that complex decision-making need not be invoked in animal contests to achieve adaptive outcomes. Our results demonstrate that physics-based classification and modeling, in terms of effective rules of interaction, provide a powerful framework for understanding animal contest behaviors.

Testosterone, signal coloration, and signal color perception in male zebra finch contests.

Many animals use assessment signals to resolve contests over limited resources while minimizing the costs of those contests. The carotenoid-based orange to red bills of male zebra finches (Taeniopygia guttata) are thought to function as assessment signals in male-male contests, but behavioral analyses relating contest behaviors and outcomes to bill coloration have yielded mixed results. We examined the relationship between bill color and contests while incorporating measurements of color perception and testosterone (T) production, for an integrative view of aggressive signal behavior, production, and perception. We assayed the T production capabilities of 12 males in response to a gonadotropin-releasing hormone (GnRH) challenge. We then quantified the initiation, escalation, and outcome of over 400 contests in the group, and measured bill color using calibrated photography. Finally, because signal perception can influence signal function, we tested how males perceive variation in bill coloration, asking if males exhibit categorical perception of bill color, as has been shown recently in female zebra finches. The data suggest that males with greater T production capabilities than their rivals were more likely to initiate contests against those rivals, while males with redder bills than their rivals were more likely to win contests. Males exhibited categorical color perception, but individual variation in the effect of categorical perception on color discrimination abilities did not predict any aspects of contest behavior or outcomes. Our results are consistent with the hypotheses that T plays a role in zebra finch contests and that bill coloration functions as an aggressive signal. We suggest future approaches, based on animal contest theory, for how links among signals, perception, and assessment can be tested.

Once bitten, twice shy: Aggressive and defeated pigs begin agonistic encounters with more negative emotions

Aggression between unfamiliar commercial pigs is common and likely invokes strong emotions in contestants. Furthermore, contest outcomes affect subsequent aggressive behaviour, suggesting a potential lasting influence on affective state. Here we used a combination of qualitative and quantitative methods to assess the emotional expression of pigs in agonistic encounters. We investigated how recent victory or defeat influences emotions expressed in a subsequent contest, and the role of aggressiveness as a personality trait in emotional expression. We observed the pre-escalation contest behaviour (second contest; age 13 wks) in animals of different aggressiveness (categorised using two resident intruder tests as Agg+ or Agg-, age 9 wks), which had recently won or lost a contest (first contest; 10 wks). We measured gaze direction and ear position. Observers watched video clips of the initial 30 s of the second contest and evaluated the emotional expression of 57 pigs (25 contest 1 winners, 32 contest 1 losers) using qualitative behavioural assessment (QBA) with a fixed list of 20 descriptive terms.QBA identified three principal components (PCs), accounting for 68% of the variation: PC1 (agitated/tense to relaxed/content), PC2 (fearful/aimless to confident/enjoying) and PC3 (listless/ indifferent). Agg- pigs and males showed a more positive emotionality (PC2). PC1 and PC3 were unaffected by first contest outcome and aggressiveness. Agg+ pigs were more likely to hold their ears back (X2 =7.8, p = 0.005) during the early contest period. Differences in attention were detected in the contest outcome × aggressiveness interaction (χ24.3, p = 0.04), whereby approaching the opponent was influenced by winning and losing in the Agg- pigs only. QBA and gaze behaviour reveal differences in emotional valence between pigs of different aggressiveness: less aggressive pigs may be more susceptible to the emotional impact of victory and defeat but overall, more aggressive pigs express more negative emotionality at the start of agonistic encounters.

Which effort pays off? Analyzing ideators’ behavioral patterns on corporate ideation platforms

AbstractThe challenge of developing high‐quality ideas as the basis of new goods and services is an important topic that coincides with companies’ rapid development of these products. In response, firms increasingly rely on online ideation platforms for ideation contests to optimize their employees’ creative power. This optimization requires a profound understanding of online ideation contests’ underlying mechanisms, specifically the participants’ innovative behavior that contributes to generating, elaborating, and championing ideas based on each ideator's effort distribution, namely their behavioral patterns. Our analysis of the ideators’ behavioral patterns and their relationship to idea success consists of two steps. First, we combine contest theory with innovative behavior literature to derive eight types of innovative behavior in online contests—clustered into the three categories idea generation, elaboration, and championing—that represent the ideators’ required efforts to compete in an ideation contest successfully. Second, we use a unique empirical sample, which combines platform and evaluation data of a corporate R&D ideation contest with participants’ survey data, received a few days before the contest's closure, to analyze the relationship between the effort invested in these dimensions and idea success. The results show that more effort does not necessarily lead to better results. The effort invested in idea generation, such as more extensive submission (“spamming”) and creative inspiration (“copying”), could be wasted and even has adverse effects on idea success. However, especially effort invested into idea championing provides strong possibilities to increase idea success.

Modulating the activity of right temporo-parietal junction increases bidding behavior in lottery contests

Contest often involves bids that are higher than the Nash equilibrium, and overbidding behaviour closely relates to personal reasoning and judgement. The right temporo-parietal junction (rTPJ) plays an important role in social, cognitive and inference decision-making. In the present study, we investigated the effect of transcranial direct current stimulation (tDCS) of the rTPJ on overbidding behaviour by using a modified model-lottery contests task. Our results showed that participants that received cathodal-stimulation had significantly higher expenditure compared to participants that received anodal and sham stimulation. Cathodal-stimulation may reduce the participants’ ability to infer other contestants’ intention or may modulate the non-monetary utility of winning. Our data indicate that excitability of the rTPJ may contribute to overbidding behaviour.

Influence of age and individual identity in the use of breeding colony habitat by male Weddell seals in Erebus Bay, Antarctica

AbstractMale–male contest behavior can contribute to spatial distributions of male pinnipeds during breeding seasons. To maximize breeding opportunities, the most competitive males would be expected to be surrounded by the highest numbers of reproductive‐age females. As information regarding fine‐scale spatial ecology of Weddell seals is lacking, we performed an exploratory study using kernel density analyses to evaluate age‐specific habitat use of male Weddell seals in Erebus Bay, Antarctica. Additionally, we investigated the relationship between age and number of surrounding reproductive‐age females using a competing set of regression models in a Bayesian framework that considered different functional forms of age while incorporating individual heterogeneity. As male adult Weddell seals aged, to at least 20 years, they were more likely to be found in areas associated with the greatest densities of reproductive‐age females, but individual heterogeneity also influenced the number of reproductive‐age female neighbors. The youngest males tended to haul out in offshore areas associated with better hunting, and older males tended to settle in more nearshore areas associated with more pup production. Our findings from this preliminary investigation indicate that male Weddell seal spatial behavior during the breeding season varies with age and individual and might be related to reproductive activity.

Extrinsic stressors modulate resource evaluations: insights from territoriality under artificial noise

BackgroundCompetition is considered to rely on the value attributed to resources by animals, but the influence of extrinsic stressors on this value remains unexplored. Although natural or anthropogenic environmental stress often drives decreased competition, assumptions that this relies on resource devaluation are without formal evidence. According to theory, physiological or perceptual effects may influence contest behaviour directly, but motivational changes due to resource value are expected to manifest as behavioural adjustments only in interaction with attainment costs and resource benefits. Thus, we hypothesise that stressor-induced resource devaluations will impose greater effects when attainment costs are high, but not when resource benefits are higher. Noise may elicit such effects because it impacts the acoustic environment and imposes physiological and behavioural costs to animals. Therefore, we manipulated the acoustic environment using playbacks of artificial noise to test our hypotheses in the territorial male Siamese fighting fish, Betta splendens.ResultsCompared to a no-playback control, noise reduced defense motivation only when territory owners faced comparatively bigger opponents that impose greater injury costs, but not when territories also contained bubble nests that offer reproductive benefits. In turn, nest-size decreases were noted only after contests under noise treatment, but temporal nest-size changes relied on cross-contest variation in noise and comparative opponent size. Thus, the combined effects of noise are conditional on added attainment costs and offset by exceeding resource benefits.ConclusionOur findings provide support for the hypothesised modulation of resource value under extrinsic stress and suggest implications for competition under increasing anthropogenic activity.

Risky choices in a natural experiment from Turkey: Var Mısın Yok Musun?

In this paper, we study high-stakes risky choices of contestants in the Turkish edition of the popular TV game show Deal or No Deal. We conduct a large-scale replication of Post, Van den Assem, Baltussen, and Thaler (2008), and we investigate contestant behavior in Turkey in detail via the expected utility and cumulative prospect theory. We find strong empirical support on the role of path dependence in shaping risk attitudes: Turkish contestants who enjoy early gains or suffer early losses in the initial rounds of the game are more risk-lover than other contestants, which aligns well with the break-even and house-money effects à la Thaler and Johnson (1990). We also document that the cumulative prospect theory predicts contestant behavior better than the expected utility theory empirically. Finally, we demonstrate that risk aversion exhibits sizable heterogeneity over demographics, and female and university-graduate contestants are more risk-averse than their male and less-educated counterparts.