3,334 research outputs found

    Visual Perception of Dynamic Properties and Events: Collisions and Throws

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    The central topic of this dissertation is visual perception of dynamic events. The topic is worth of interest, as witnessed by its long tradition in the history of Experimental Psychology, starting with the seminal work of Albert Michotte (1881 - 1965) on phenomenal causality. Thus, the topic I chose is not original in itself. However, a distinctive element of novelty in my dissertation is the use of Computer Graphics techniques as a means for creating realistic experimental stimuli in psychological experiments. Besides the advantage of reducing the gap between laboratory experiments and everyday experience, this may reveal the importance of experimental variables which traditionally have been ignored in research on visual perception of dynamic events. The reader should be informed that this dissertation is characterized by various lines of research, which are intrinsically connected with the central topic of visual perception of dynamic events. In some of the experiments, I investigate visual perception of dynamic events, whereas in others I investigate cognition of the same events. Two distinct dynamic events will be especially studied: horizontal collisions and throws. Moreover, the results of the experiments will be discussed not only in relation to their theoretical implications for psychological models, but also in relation to their potential applications to Physics education and Computer Graphics. As a result, the content of the dissertation is quite heterogeneous, but I hope to provide the reader with a broad and multidisciplinary perspective on the subject at hand. The dissertation is composed of five chapters, which may be divided into three groups. (i) In Chapters 1-3, after a presentation of the theoretical background of visual perception of dynamic events, I investigate the influence of dynamic properties of virtual objects on visual perception of horizontal collisions. The results of this research are important for the old and still active debate on phenomenal causality. (ii) In Chapter 4 I present a research on Naïve Physics of horizontal collisions between virtual spheres differing in simulated mass and velocity. In this chapter I take a more cognitive (rather than perceptual) perspective on dynamic events, investigating how people reason about the proposed physical event. (iii) In Chapter 5, I present a research on visual perception of virtual throwing animations, which are complex and rarely studied dynamic events. This chapter stands out for its multidisciplinary nature, as in it I discuss how the results can be applied to Computer Graphics. The research presented in this last chapter has been conducted as a part of my doctorate studies when I was a visiting PhD student at the Graphics, Vision, and Visualisation Group at Trinity College Dublin, where I collaborated with Professor Carol O’Sullivan and Doctor Ludovic Hoyet, who are computer scientists working on applications of visual perception to Computer Graphics. In more detail, in Chapter 1 I discuss the theoretical background of visual perception of dynamic events and phenomenal causality. Firstly, I focus on Michotte’s classical work. Secondly, I discuss some prominent issues which have been debated for a long time in this field of research. Lastly, I present White’s schema-matching model of visual perception of dynamic events, discussing its differences and similarities as compared with Michotte’s model. This chapter is intended to serve as a theoretical point of reference for the entire dissertation. In Chapter 2 I discuss the hypothesis that visually perceived dynamic properties of objects involved in dynamic events do influence visual perception of the dynamic events themselves. Firstly, I try to confute two popular arguments against this hypothesis. Then, I highlight the evolutionary advantage of visual perception of dynamic properties, discussing their possible influence on visual perception of dynamic events. Lastly, I discuss Runeson’s KSD model in relation to the presented hypothesis. In Chapter 3 I present three experiments which confirm the hypothesis discussed in Chapter 2. In particular, I show that simulated material (Experiment 1) and size (Experiments 2 and 3) of virtual objects involved in horizontal collisions strongly influence how observers perceive the event. I also discuss the theoretical implications of these findings by referring to Michotte’s and White’s models. In Chapter 4 I present a research on Naïve Physics of horizontal collisions. Firstly, I discuss the general importance of studying Naïve Physics for improving basic education in Physics. Secondly, I present Information Integration Theory and Functional Measurement methodology as suitable tools for the assessment of students’ intuitive knowledge of physical events, evidencing their advantages over multiple-choice surveys. Lastly, I present two experiments (conducted using Information Integration Theory and Functional Measurement) on Naïve Physics of horizontal collisions between simulated spheres differing in size, velocity, and material. The importance of the results for Physics instruction will also be discussed. Finally, in Chapter 5 I present a research on visual perception of edited virtual throwing animations. First I discuss the relations between visual perception of dynamic events (human motion in particular) and Computer Graphics. Then, I present two experiments on observers’ sensitivity to anomalies in realistic virtual throwing animations, discussing the importance of the results for videogames and movies industry

    Performance monitoring during action observation and auditory lexical decisions

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    How does the brain monitor performances? Does expertise modulate this process? How does an observer’s error related activity differ from a performers own error related activity? How does ambiguity change the markers of error monitoring? In this thesis, I present two EEG studies and a commentary that sought to answer these questions. Both empirical studies concern performance monitoring in two different contexts and from two different personal perspectives, i.e. investigating the effects of expertise on electroencephalographic (EEG) neuromarkers of performance monitoring and in terms of monitoring own and others’ errors during actions and language processing. My first study focused on characterizing the electrophysiological responses in experts and control individuals while they are observing domain-specific actions in wheelchair basketball with correct and wrong outcomes (Chapter II). The aim of the commentary in the following chapter was to highlight the role of Virtual Reality approaches to error prediction during one’s own actions (Chapter III). The fourth chapter hypothesised that the error monitoring markers are present during both one’s own performance errors in a lexical decision task, and the observation of others’ performance errors (Chapter IV), however, the results suggested a further modulation of uncertainty created by our task design. The final chapter presents a general discussion that provides an overview of the results of my PhD work (Chapter V). The present chapter consists of a literature review in the leading frameworks of performance monitoring, action observation, visuo-motor expertise and language processing

    FAST : a fault detection and identification software tool

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    The aim of this work is to improve the reliability and safety of complex critical control systems by contributing to the systematic application of fault diagnosis. In order to ease the utilization of fault detection and isolation (FDI) tools in the industry, a systematic approach is required to allow the process engineers to analyze a system from this perspective. In this way, it should be possible to analyze this system to find if it provides the required fault diagnosis and redundancy according to the process criticality. In addition, it should be possible to evaluate what-if scenarios by slightly modifying the process (f.i. adding sensors or changing their placement) and evaluating the impact in terms of the fault diagnosis and redundancy possibilities. Hence, this work proposes an approach to analyze a process from the FDI perspective and for this purpose provides the tool FAST which covers from the analysis and design phase until the final FDI supervisor implementation in a real process. To synthesize the process information, a very simple format has been defined based on XML. This format provides the needed information to systematically perform the Structural Analysis of that process. Any process can be analyzed, the only restriction is that the models of the process components need to be available in the FAST tool. The processes are described in FAST in terms of process variables, components and relations and the tool performs the structural analysis of the process obtaining: (i) the structural matrix, (ii) the perfect matching, (iii) the analytical redundancy relations (if any) and (iv) the fault signature matrix. To aid in the analysis process, FAST can operate stand alone in simulation mode allowing the process engineer to evaluate the faults, its detectability and implement changes in the process components and topology to improve the diagnosis and redundancy capabilities. On the other hand, FAST can operate on-line connected to the process plant through an OPC interface. The OPC interface enables the possibility to connect to almost any process which features a SCADA system for supervisory control. When running in on-line mode, the process is monitored by a software agent known as the Supervisor Agent. FAST has also the capability of implementing distributed FDI using its multi-agent architecture. The tool is able to partition complex industrial processes into subsystems, identify which process variables need to be shared by each subsystem and instantiate a Supervision Agent for each of the partitioned subsystems. The Supervision Agents once instantiated will start diagnosing their local components and handle the requests to provide the variable values which FAST has identified as shared with other agents to support the distributed FDI process.Per tal de facilitar la utilització d'eines per la detecció i identificació de fallades (FDI) en la indústria, es requereix un enfocament sistemàtic per permetre als enginyers de processos analitzar un sistema des d'aquesta perspectiva. D'aquesta forma, hauria de ser possible analitzar aquest sistema per determinar si proporciona el diagnosi de fallades i la redundància d'acord amb la seva criticitat. A més, hauria de ser possible avaluar escenaris de casos modificant lleugerament el procés (per exemple afegint sensors o canviant la seva localització) i avaluant l'impacte en quant a les possibilitats de diagnosi de fallades i redundància. Per tant, aquest projecte proposa un enfocament per analitzar un procés des de la perspectiva FDI i per tal d'implementar-ho proporciona l'eina FAST la qual cobreix des de la fase d'anàlisi i disseny fins a la implementació final d'un supervisor FDI en un procés real. Per sintetitzar la informació del procés s'ha definit un format simple basat en XML. Aquest format proporciona la informació necessària per realitzar de forma sistemàtica l'Anàlisi Estructural del procés. Qualsevol procés pot ser analitzat, només hi ha la restricció de que els models dels components han d'estar disponibles en l'eina FAST. Els processos es descriuen en termes de variables de procés, components i relacions i l'eina realitza l'anàlisi estructural obtenint: (i) la matriu estructural, (ii) el Perfect Matching, (iii) les relacions de redundància analítica, si n'hi ha, i (iv) la matriu signatura de fallades. Per ajudar durant el procés d'anàlisi, FAST pot operar aïlladament en mode de simulació permetent a l'enginyer de procés avaluar fallades, la seva detectabilitat i implementar canvis en els components del procés i la topologia per tal de millorar les capacitats de diagnosi i redundància. Per altra banda, FAST pot operar en línia connectat al procés de la planta per mitjà d'una interfície OPC. La interfície OPC permet la possibilitat de connectar gairebé a qualsevol procés que inclogui un sistema SCADA per la seva supervisió. Quan funciona en mode en línia, el procés està monitoritzat per un agent software anomenat l'Agent Supervisor. Addicionalment, FAST té la capacitat d'implementar FDI de forma distribuïda utilitzant la seva arquitectura multi-agent. L'eina permet dividir sistemes industrials complexes en subsistemes, identificar quines variables de procés han de ser compartides per cada subsistema i generar una instància d'Agent Supervisor per cadascun dels subsistemes identificats. Els Agents Supervisor un cop activats, començaran diagnosticant els components locals i despatxant les peticions de valors per les variables que FAST ha identificat com compartides amb altres agents, per tal d'implementar el procés FDI de forma distribuïda.Postprint (published version

    Analysis of the services as a performance factor in high-level volleyball and beach volleyball

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    L’objectiu final d’aquesta Tesi és identificar aspectes crítics de la utilització del servei en el voleibol i voleibol de platja d’alt nivell. Per aconseguir-ho quatre estudis, emmarcats dintre de l’anàlisi del rendiment esportiu, es van dur a terme. Els resultats de les nostres investigacions mostren que el servei és una habilitat tècnica important en les disciplines del voleibol però no pot explicar per si mateixa el resultat d’un partit. No obstant això, sembla un element clau en la prevenció d’atacs contraris eficaços i el seu resultat està clarament influenciat per les habilitats executades en salt. Una execució reeixida del servei és una qüestió complexa, i té una component física, tècnica, estratègica i tàctica. Una correcta utilització d’aquesta habilitat tècnica és fonamental per desequilibrar el resultat d’un partit. Ara bé, altres aspectes han estat identificats també com a rellevants per tenir èxit en un partit de voleibol o voleibol de platjaThe ultimate goal of this Dissertation was to identify critical aspects of the use of service in high-level volleyball and beach volleyball. To address this purpose four studies on different aspects of service performance, framed into the field of performance analysis, were conducted. The results of our investigation show that service is a very important skill in volleyball disciplines but it cannot explain by itself the result of a match. Nevertheless, it seems a key element in preventing an effective attack. Service behavior and its ability to impair the opponent’s game is clearly influenced by jump abilities. The successful execution of the service is a complex issue, and has a physical, technical, strategic and tactical component. Proper use of this technical skill is capital in making the result of a match uneven. However, some other aspects have been identified as relevant to success in a volleyball or beach volleyball match

    The subjective construal of social exclusion : an integrative model

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    Research on social exclusion has mainly focused on situations in which exclusion is highly ambiguous and represents a violation of prevailing inclusion norms. However, it has rarely been accounted for that social exclusion situations are subjectively construed by the involved actors. In this dissertation, I suggest that subjective reactions to exclusion are cognitively mediated and do not necessarily depend on objective qualities of the exclusion experience. I further present a construal-based model of social exclusion that frames the construal of social exclusion as a function of norm consistency (whether social exclusion is consistent with or violating social norms) and the adopted perspective (targets, sources, and observers). This dissertation contains four manuscripts, which emphasize the important role of subjective construal. Rudert, Hales, Greifeneder, and Williams (2016) showed that minimal acknowledgement affects the subjective experience of exclusion more strongly than the objective amount of exclusion. Rudert and Greifeneder (2016) demonstrated that targets’ negative reactions to exclusion are attenuated if exclusion is perceived as consistent with compared to violating the prevailing social norm. Rudert, Janke, and Greifeneder (2016) investigated subjective exclusion experiences as a reaction to an anti-immigration popular vote in Switzerland and demonstrated differences due to personal norms and attitudes. Finally, Rudert, Reutner, Greifeneder, and Walker (2017) showed that observers’ moral judgment of social exclusion experiences is affected by facial characteristics of the excluded target. All manuscripts are discussed in terms of the presented model together with additional lines of research that can be derived from a perspective of subjective construal

    Weight perception during action observation: the role of motor skills and abilities

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    The aim of this work is to investigate the role that motor skills and abilities have in perceiving the weight of an object handled and moved by another person. This topic provides an understanding of the interaction between actions and perceptions by assessing how motor repertoire, either shaped during years of sport practice, or altered during aging and fatigability, modulates the way individuals perceived the movement performed by others. The first chapter (Chapter 1) presents a summary of the scientific literature about this topic, and, in particular, of the mechanisms underlying it, primarily motor resonance. Next, the state of the art on the perception of the weight of an object during the execution and observation of a movement is presented. The first study (Chapter 2) investigates the role of motor expertise and the acquisition of specific skills in assessing the weight of an object moved during a sport-specific gesture. In the second study (Chapter 3), the role of ageing and the decline of motor ability in the ability to perceive the weight of an object during the observation of an everyday life movement was investigated. In the third study (Chapter 4), the focus was on how the nature of the movement, i.e. concentric or eccentric movement, affected the ability to discriminate the weight of an object during action observation. The fourth study (Chapter 5) focused on how the state of the observer could affect this ability, specifically how fatigue affects the ability to discriminate and evaluate the weight of an object during the observation of an everyday movement
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