Near-Optimal Adversarial Policy Switching for Decentralized Asynchronous Multi-Agent Systems

A key challenge in multi-robot and multi-agent systems is generating solutions that are robust to other self-interested or even adversarial parties who actively try to prevent the agents from achieving their goals. The practicality of existing works addressing this challenge is limited to only small-scale synchronous decision-making scenarios or a single agent planning its best response against a single adversary with fixed, procedurally characterized strategies. In contrast this paper considers a more realistic class of problems where a team of asynchronous agents with limited observation and communication capabilities need to compete against multiple strategic adversaries with changing strategies. This problem necessitates agents that can coordinate to detect changes in adversary strategies and plan the best response accordingly. Our approach first optimizes a set of stratagems that represent these best responses. These optimized stratagems are then integrated into a unified policy that can detect and respond when the adversaries change their strategies. The near-optimality of the proposed framework is established theoretically as well as demonstrated empirically in simulation and hardware

Contextual information and perceptual-cognitive expertise in a dynamic, temporally-constrained task

Skilled performers extract and process postural information from an opponent during anticipation more effectively than their less-skilled counterparts. In contrast, the role and importance of contextual information in anticipation has received only minimal attention. We evaluate the importance of contextual information in anticipation and examine the underlying perceptual-cognitive processes. We present skilled and less-skilled tennis players with normal video or animated footage of the same rallies. In the animated condition, sequences were created using player movement and ball trajectory data, and postural information from the players was removed, constraining participants to anticipate based on contextual information alone. Participants judged ball bounce location of the opponent’s final occluded shot. The two groups were more accurate than chance in both display conditions with skilled being more accurate than less-skilled (Exp. 1) participants. When anticipating based on contextual information alone, skilled participants employed different gaze behaviors to less-skilled counterparts and provided verbal reports of thoughts which were indicative of more thorough evaluation of contextual information (Exp. 2). Findings highlight the importance of both postural and contextual information in anticipation and indicate that perceptual-cognitive expertise is underpinned by processes that facilitate more effective processing of contextual information, in the absence of postural information

The role of contextual information in expert anticipation

This thesis was submitted for the award of Doctor of Philosophy and was awarded by Brunel University LondonWhile it is well established that expert performers can pick up and utilise postural cues to anticipate more effectively than less-skilled counterparts, the role of contextual information in expert anticipation has received relatively little research attention. The aims of this thesis were to highlight the importance of contextual information in anticipation, identify specific sources of contextual information that impact anticipation, and examine how this information is used. In five studies, skilled and less-skilled tennis players were presented with videos or animations of the same open play rallies. The animations omitted postural information, constraining participants to anticipate based on contextual information alone. First, participants anticipated more accurately than chance in both display conditions. Skilled participants were more accurate than less-skilled participants, with the difference being greater in the video condition. Second, gaze data and retrospective verbal reports were collected when viewing the animations. Skilled participants displayed different gaze behaviour and more thoroughly evaluated the presented information than less-skilled participants. Third, animations were manipulated to depict or omit potential sources of contextual information. The preceding shot sequence was shown to be a useful source of contextual information, particularly for skilled participants. Additionally, player positioning could be used to anticipate highly accurately in absence of any other information. Finally, the option generation strategies underpinning expert anticipation were examined. Participants generated fewer options when postural cues were available compared with when constrained to the use of contextual information alone. Moreover, skilled participants generated more task-relevant and fewer task-irrelevant options than less-skilled participants. Collectively, these findings increase understanding of the role of contextual information in expert anticipation and further highlight the complex nature of perceptual-cognitive expertise

Unravelling tennis performance:creating monitoring tools to measure and understand technical and tactical skills

The key in elite tennis performance is suggested to be the combination of outstanding technical and tactical skills. However, little is known about which specific skills are important to progress towards elite tennis performance. Moreover, there are no reliable, valid and feasible tools to assess technical and tactical skills in youth tennis players. Therefore, in this thesis, tools with sufficient psychometric properties were developed to measure technical and tactical skills in a tennis-specific context - contributing to both scientific and practical purposes. An on-court tennis test was developed to assess technical skills based on accuracy (target areas), ball speed (radar system) and percentage errors. A new instrument with closed-ended questions was designed to examine tactical skills, in particular ‘Anticipation and positioning’, ‘Game intelligence and adaptability’, ‘Decision-making’, and ‘Recognizing game situations’. Our studies showed that outstanding technical skills, especially accuracy under increased task complexity (i.e. high temporal and cognitive pressure), were considered essential to progress towards elite tennis performance. Findings of this thesis also suggest that these technical skills continue to develop in adolescence in a group of youth talented tennis players. From a practical perspective, the tools created in this thesis are valuable for coaches and players to enhance tennis performance. In addition to monitoring the progress of players, tools can assist in identifying relative strengths and weaknesses of players as well as provide essential information about underlying skills that require most attention to progress towards elite performance

Execution and perception of effector-specific movement deceptions

As a topic that touches on many aspects of movement execution and perception in sports, research on deception has attracted much attention during the last ten years. However, some important questions still remain unresolved—especially what are the kinematic characteristics of more effector-specific movement deceptions that influence an observer’s perceptual recognizability? It is still not known how spatiotemporal dissimilarities between movements and/or response time distributions influence this recognizability. Three different studies were conducted to answer these questions. To embed the new findings into an applied context, a first study investigated the speed of internal processing in domain-specific and unspecific RT tasks. As well as examining speed, results also showed that motor expertise facilitated the processing of domain-specific responses. The second study examined the kinematic characteristics of effector- specific movement deceptions. This showed that expertise in performing those deceptions, as a potential kind of movement mimicry, depends mainly on keeping dissimilarities to non-deceptive movements small. A third, psychophysical study investigated the role of spatiotemporal dissimilarity and response time distribution in the perceptual recognizability of deceptive movements. Results demonstrated that recognizability increases as a function of dissimilarity; however, perceptual performance decreases in the case of early responses. To sum up, the findings presented in this dissertation contribute to a deeper understanding of how the execution and perception of effector-specific movement deceptions are linked together. On the performer side, they demonstrate that experienced athletes are able to mimic non-deceptive movements while performing effector-specific deceptions. However, this attempt becomes a challenge the closer the execution of the movement phase is to the visibility of the action outcome. On the observer side, they show that the perceptual discriminability between movements increases as a function of spatiotemporal dissimilarity. However, observers more frequently tend to produce a prediction error when giving an early response, thus, indicating the efficiency of the performed effector-specific movement deceptions.Bewegungstäuschungen spielen in verschiedensten Interaktion im Sport eine besondere Rolle. Das Forschungsinteresse zu diesem Thema hat in den letzten Jahren zunehmend an Bedeutung gewonnen. Dennoch bleiben bislang einige Fragen ungeklärt, insbesondere, welchen kinematischen Besonderheiten Effektor-spezifische Bewegungstäuschungen unterliegen und welche dieser Parameter die perzeptuelle Erkennungsleistung beeinflussen. Noch ist zum Beispiel nicht bekannt, welchen Einfluss raum-zeitliche Unterschiede zwischen den Bewegungen und/oder die Verteilung von Reaktionszeiten auf die Erkennungsleistung haben. Zur Beantwortung dieser Fragen wurden im Rahmen dieser Arbeit drei Studien durchgeführt. Um die neu gewonnenen Befunde besser in einen Anwendungskontext einzubetten, untersuchte eine erste Studie die Geschwindigkeit interner Verarbeitungsprozesse während domänenspezifischen und unspezifischen RT-Aufgaben. Zudem zeigten die Ergebnisse, dass motorische Expertise zu einer schnelleren Verarbeitung domänenspezifischer Reaktionen beiträgt. Die zweite Studie im Rahmen dieser Dissertation untersuchte die kinematischen Eigenschaften von Effektor-spezifischen Bewegungstäuschungen. Es konnte gezeigt werden, dass die Ausführung Effektor-spezifischer Täuschungen, als eine Art “Bewegungs-Mimikry”, insbesondere eine möglichst präzise Anpassung der räumlichen Parameter an nicht getäuschte Bewegungen erfordert. Eine dritte, psychophysische Studie untersuchte im Folgenden die Rolle von raum-zeitlichen Unterschieden sowie die Verteilung von Reaktionszeiten auf die perzeptuelle Erkennungsleistung getäuschter Bewegungen. Die Resultate zeigten, dass die Erkennungsleistung mit einer Zunahme an raum- zeitlichen Unterschieden linear ansteigt. Die Ergebnisse der vorliegenden Dissertation tragen erheblich zum tieferen Verständnis der Ausführung und Wahrnehmung von Effektor-spezifischen Bewegungstäuschungen bei. Auf der Seite der Bewegungsausführung konnte gezeigt werden, dass erfahrene Athleten bei der Ausführung von Täuschungen in der Lage sind nicht getäuschte Bewegungen zu imitieren. Dennoch scheint dieser Ansatz immer schwieriger zu werden, je weiter sich die Bewegung der Sichtbarkeit des Handlungseffektes nähert. Auf der Seite des Beobachters wurde deutlich, dass sich perzeptuelle Diskriminanzleistungen mit dem Anstieg an raum-zeitlichen Unterschieden zwischen den beobachteten Bewegungen verstärkt. Allerdings zeigte sich auch, dass Beobachter häufiger zu Vorhersagefehlern tendierten, wenn frühe Einschätzungen abgegeben wurden. Dies spricht im Gegenzug für die Effektivität der ausgeführten Effektor-spezifischen Bewegungstäuschungen

Bounded rationality for relaxing best response and mutual consistency: The Quantal Hierarchy model of decision-making

While game theory has been transformative for decision-making, the assumptions made can be overly restrictive in certain instances. In this work, we focus on some of the assumptions underlying rationality such as mutual consistency and best response, and consider ways to relax these assumptions using concepts from level-$k$ reasoning and quantal response equilibrium (QRE) respectively. Specifically, we provide an information-theoretic two-parameter model that can relax both mutual consistency and best response, but can recover approximations of level-$k$, QRE, or typical Nash equilibrium behaviour in the limiting cases. The proposed Quantal Hierarchy model is based on a recursive form of the variational free energy principle, representing self-referential games as (pseudo) sequential decisions. Bounds in player processing abilities are captured as information costs, where future chains of reasoning are discounted, implying a hierarchy of players where lower-level players have fewer processing resources. We demonstrate the applicability of the proposed model to several canonical economic games.Comment: 36 pages, 15 figure

Identifying the visual information and processes underlying expert judgements of deceptive intent

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel UniversityThe aims of the current research programme were, first, to examine expertise effects with regard to anticipation skill and the perception of deceptive movement, and, second, to examine how knowledge of the probability of behavioural events influences anticipation performance and visual search behaviour. In addition, this thesis sought to test the predictions of attentional control theory (ACT) in examining how anxiety affects the influence of top-down probability information on anticipation skill and visual search behaviour. In Chapter 3, skill-based differences in anticipation and decision making were examined using judgement accuracy and confidence ratings. High-skilled soccer players demonstrated superior anticipatory performance and were less susceptible to deception compared with low-skilled players. In Chapters 4 and 5 Posner’s spatial cueing paradigm was adapted to examine the influence of top-down probability information on anticipation skill and visual search behaviour. High-skilled participants were found to be more accurate and demonstrate more efficient visual search behaviour compared to low-skilled participants. However, findings demonstrated that both groups benefited from the provision of probability information, and performance was moderated by the degree of certainty conveyed through the probability information. In Chapter 6, the same anticipation task and process tracing measures were used to examine the effects of heightened anxiety on the processing of probability and visual information. The findings supported the predictions of ACT, as the influence of top-down information was suppressed during high-pressure conditions, owing to an increased influence of the stimulus-driven attentional control system. The series of studies in this thesis are the first to explore the influence of top-down probability information on anticipation performance and the perception of deception. Study 4 is also the first to test the predictions of ACT regarding the processing of (top-down) explicit knowledge and (bottom-up) visual information under pressure during a simulated soccer anticipation task. The use of probability information through performance analysis feedback plays a prominent role across a number of sports, and the present findings highlight the importance of understanding the costs and benefits associated with such information. It is concluded that future perceptual training interventions should incorporate context-specific information that mimics the real-life demands of competitive sport, and should be directed towards enhancing players' ability to detect deception rather than training players to become attuned to non-deceptive movement