Dissertations / Theses on the topic 'Conscious Processing'
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Rafter, Anne. "Non-conscious processing in anxiety." Thesis, University of Cambridge, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.620156.
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Mullen, Richard Hugh. "State anxiety, conscious processing and motor performance." Thesis, Bangor University, 2000. https://research.bangor.ac.uk/portal/en/theses/state-anxiety-conscious-processing-and-motor-performance(5822a5eb-fcf4-475a-a233-ac775259b45f).html.
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This thesis examined the conscious processing hypothesis as a potential explanation for the way in which anxiety affects motor performance. The thesis is written as a series of research papers (studies). The five papers are preceded by a general introduction and followed by a general discussion. The first study replicated and extended previous research in the area of conscious processing. Participants acquired the skill of golf putting explicitly and implicitly across 400 trials. During a high anxiety transfer test, the performance of participants who learned explicitly was less robust than that of participants who learned implicitly, supporting the conscious processing hypothesis. Study 2 tested the conscious processing hypothesis using a performance rather than learning paradigm to control for possible desensitisation effects identified as a possible alternative explanation for the results of study 1. Results supported the conscious processing hypothesis, but an alternative attentional explanation was identified. Study 3 examined the conscious processing hypothesis while controlling for both desensitisation and attentional effects. Kinematic measures were also adopted to examine the golf putting task in vivo. Performance results partially supported the conscious processing hypothesis. Study 4 replicated and extended the design adopted in study 3. Study 4 also examined processing efficiency theory as a plausible alternative to the conscious processing hypothesis. Kinematic and cardiovascular measures were incorporated into the design. Performance scores suggested a processing efficiency interpretation. However, conscious processing effects could not be totally discounted. The fifth study examined the suggestion that the use of process goals by skilled but anxious performers might actively encourage lapses into conscious processing. Increases in state anxiety did not produce performance decrements. A lack of training in the use of goals was identified as an explanation for the absence of performance impairment. Implications for future research and applied practice are derived from the five studies.
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Poland, Eva [Verfasser]. "Neural correlates of conscious visual processing / Eva Poland." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2021. http://d-nb.info/123522256X/34.
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Strain, Eamon. "Automatic, preattentive processing and its influence on overt conscious behaviour." Thesis, Queen's University Belfast, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334645.
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Stewart, Fiona Margaret. "On-line and off-line semantic processing in aphasia." Thesis, University of Newcastle Upon Tyne, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366587.
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Berkovitch, Lucie. "Non-conscious processing, attentional amplification and conscious access : experimental investigations in healthy controls and patients with schizophrenia Disruption of conscious access in schizophrenia Impaired conscious access and abnormal attentional amplification in schizophrenia." Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS405.
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Dans de nombreuses études, les personnes atteintes de schizophrénie présentent une élévation du seuil de perception consciente alors que le traitement subliminal est préservé. Dans cette thèse, nous nous appuyons sur cette dissociation conscient-subliminal pour explorer l’accès conscient et les processus non conscients. Nous montrons que le seuil de conscience est associé à une dysconnectivité cérébrale chez les patients atteints de psychose, ce qui favoriserait la survenue de symptômes psychotiques. Nous explorons ensuite comment les facteurs attentionnels modulent l’accès conscient. Nos résultats indiquent qu’une accumulation d’évidence a lieu en l’absence d’attention, et qu’elle est amplifiée par la focalisation attentionnelle chez les sujets sains mais pas chez les patients atteints de schizophrénie. Trois études supplémentaires chez les sujets sains explorent les interactions entre facteurs descendants et ascendants. Une première étude montre une synergie entre clignement attentionnel et masquage dans la perturbation de l’accès conscient. Une seconde expérience suggère que les événements violant les attentes d’un sujet sont plus facilement identifiés que ceux qui les confirment ou sont aléatoires. Enfin, une étude sur le langage indique que les caractéristiques syntaxiques peuvent être extraites inconsciemment et induire différents niveaux d’amorçageIn many studies, persons with schizophrenia exhibited an elevated threshold for conscious perception while subliminal processing was preserved. In this thesis, we rely on this dissociation between conscious and subliminal processing to examine conscious access mechanisms and non-conscious processing. We found that consciousness threshold was associated with cerebral dysconnectivity in patients with psychosis, which may favour psychotic symptoms. We explored how attentional factors modulated conscious access in healthy controls and patients with schizophrenia. We showed that an accumulation of evidence could occur under unattended conditions and was tremendously amplified for attended stimuli in healthy controls but not in patients with schizophrenia. We conducted three additional studies in healthy controls to further study interactions between bottom-up and top-down processing. In a first study, we observed a synergy between attentional blink and visual masking in preventing conscious access. In a second experiment, we examined whether predicted events were better processed under low visibility conditions and found that stimuli violating expectations were more easily identified than confirming or random ones. Finally, we conducted behavioural experiments on language, revealing that syntactic features could be subliminally extracted and induce different levels of priming
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Faull, Andrea Leigh. "Anxiety and motor performance : conscious processing and the process goal paradox." Thesis, Cardiff Metropolitan University, 2010. http://hdl.handle.net/10369/894.
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This thesis examined the process goal paradox and the conscious processing hypothesis (CPH; Masters, 1992) as an explanation for performance decrements in conditions of high cognitive state anxiety. The aims of the thesis were to: (1) investigate the process goal paradox as a means of examining conscious processing effects, (2) examine the number of part process goals as a method of inducing conscious processing and (3) to make use of an interdisciplinary approach to uncover the mechanisms underlying conscious processing effects. The thesis comprised four empirical studies that adopted a range of methodological approaches including quantitative and qualitative research. Study 1 examined the process goal paradox using a part process goal, a holistic process goal, an external goal and a discovery learning group in a driving simulation task in acquisition and across neutral and competition conditions. Study 2 investigated the process goal paradox using a part process goal, a holistic process goal and an external goal, in novice and expert performers in a basketball free throw task in low and high anxiety conditions. Study 3 examined the impact of using a varying number of part process goals when performing under high and low anxiety conditions in expert tennis players. Overall the findings of studies 1, 2 and 3 supported the use of goals in preventing performance decrements under conditions of high anxiety. No support was found for conscious processing. Subsequently, study 4 aimed to ascertain the causes and mechanisms that contribute to performance failure under pressure. Overall, the results of study 4 suggest that performance decrements under conditions of high anxiety are more suitably explained by attentional based theories such as Processing Efficiency Theory (PET; Eysenck & Calvo, 1992) rather than self focus explanations, such as the CPH.
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RUTIGLIANO, TERESA. "MVAR ANALYSIS OF IEEG SIGNALS TO DIFFERENTIATE CONSCIOUS STATES." Doctoral thesis, Università degli Studi di Milano, 2018. http://hdl.handle.net/2434/547119.
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Neuroscience is a highly multidisciplinary and rapidly evolving research field. An important recent challenge of this discipline is the investigation of the so-called connectome. According to its original meaning, connectome is the map of the all brain neural connections. In this framework, the cognitive processes are not seen as localized in specific loci, but stored and processed in a distributed manner. Connectome aims to map and under-stand the organization of neural interactions trying, at the same time, to explain the role of functional units within the brain system. In particular, one of the most difficult and un-solved tasks in neuroscience is the identification of the areas, connections or brain func-tions that are called neuronal correlates of consciousness (NCCs).
In this thesis the neural activity was explored by analysing human brain signals ac-quired during medical procedure. Signals from patients with drug resistant epilepsy were acquired by means of electrodes placed deep in the cortex (intracranial electroencephalog-raphy, EEG-iEEG), positioned in order to localize the epileptogenic focus. The technique, called stereotactic EEG (SEEG), guided and flanked by detailed 3D images, also pro-vides for periodical intracranial single-pulse electrical stimulation (SPES) to highlight are-as of interest. The continuous recording of the EEG activity took place for several days, and signals were grouped in two datasets: one acquired during wakefulness (WAKE) and the other one during the Non-Rapid Eye Movement sleep (NREM), stage 3.
The signals were processed by means of two methods based on a multivariate auto-regressive model (MVAR). The first method was DTF (Directed Transfer Function), that is an estimator of the information flow between structures, depending on the signal fre-quency; it is able to describe which structure influences another. The second one was ADTF (Adaptive DTF) that permits to study the time-variant signal features, capturing their temporal dynamics. In addition to these connectivity analysis, feature extraction and classification techniques have been employed.
The main aim of the dissertation is to evaluate methods and carry out analyses useful to distinguish between conscious and unconscious states, corresponding to WAKE and NREM respectively, studying at the same time the brain connectivity in response to Single Pulse Electrical Stimulation in intracranial EEG data.
Massimini’s group (Department of Biomedical and Clinical sciences “L. Sacco”, Uni-versità degli Studi di Milano) revealed a different behavior for signals from the two states, WAKE and NREM: they noted a reactivation of the signal around 300 ms after the system perturbation in WAKE and, in contrast, a period of neural silence (down-state) in NREM condition. A hypothesis about the origin of the reactivation phenomenon is a feedback activity, i.e. the result of the activity from the rest of the network. In the thesis, the ADTF method was chosen to shed light on the down-state effect, paying attention to a defined temporal slice of data. The analysis was completed by the application of the DTF procedure, that was chosen to compare the two consciousness states and underline their differences in the frame of network connectivity.
The analysis carried out lead to the following results:
Indication of useful combinations of features and techniques able to distinguish the states of interest
Observations of neural connection changes over frequency and time consider-ing causal relationships
Comparison of connectivity results using different re-referencing styles
Endorsement of the anatomical-functional importance of some channels corre-sponding to specialized brain areas.
As conclusion of the analysis it was possible to identify a series of anatomical-functional brain features useful to discriminate the two mentioned states, therefore to speculate on the possibility to differentiate conscious and unconscious states with computational tools.
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King, Jean-Remi. "Characterizing electro-magnetic signatures of conscious processing in healthy and impaired human brains." Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066023.
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Nous n’avons pas conscience de l’ensemble des processus réalisés par notre cerveau à chaque instant. Cette dissociation entre l’expérience subjective et l’activité neuronale présente un défi majeur à la fois pour les neurosciences fondamentales, mais également pour la pratique clinique. En effet, non seulement les mécanismes neuronaux de la prise de conscience sont mal compris, mais il reste extrêmement difficile de déterminer si des patients en état végétatif – éveillés mais non-communicants – perçoivent leur environnement consciemment. Ces questions théorique et clinique constituent les deux axes principaux de cette thèse. Dans un premier temps, je développe, à partir des récentes avancées aussi bien empiriques que théoriques, une série d’outils permettant de caractériser les mécanismes neuronaux et computationnels de la perception consciente. En particulier, je montre dans une première étude comment les analyses de classification multivariée permettent de décoder les signaux magnéto- et électro-encéphalographiques à l’échelle de l’essai unique. De plus, dans trois études successives, je propose de nouvelles méthodes de traitement du signal permettant de i) caractériser la structure dynamique des processus évoqués par une stimulation sensorielle ii) de quantifier la quantité d’information échangées entre différentes régions corticales et iii) d’estimer la complexité des réponses cérébrales. Enfin, je montre comment un modèle mathématique utilisant les principes d’inférence bayésienne permet de rendre compte d’un grand nombre de résultats observés dans les études de la perception consciente et inconsciente. Dans un second temps, j’applique ces méthodes aux EEG d’une large cohorte de patients végétatifs, minimalement conscients et conscients. Les résultats montrent que les patients végétatifs présentent i) une altération des réponses corticales tardives évoquées par une stimulation auditive, ii) une diminution de l’échange d’information entre régions cérébrales, iii) des rythmes EEG moyens et lents (< 13Hz) anormaux et iv) une réduction de la complexité de l’activité EEG. A l’avenir, ces différentes signatures neurales de la conscience pourraient être utilisées en synergie pour décoder le contenu conscient et aider au diagnostic, au pronostic et au monitoring des patients non-communicantsWe are not aware of everything our brain does. This dissociation between subjective experience and objective neural activity challenges both theoretical neuroscience and clinical practice. Indeed, not only are the neuronal mechanisms of conscious perception poorly understood, but it remains extremely difficult to deter-mine whether vegetative state patients – who are thus awake but non-communicating – perceive their envi-ronment consciously. These theoretical and clinical questions constitute the two main axes of this thesis. In a first part, I develop, from the recent empirical and theoretical advances, a series of methods to characterize the neural and computational mechanisms of conscious perception. In particular, I show in a first study how multivariate pattern classifiers can decode magneto- and electroencephalographic recordings at the single trial level. In three successive studies, I then propose new signal processing methods to i) characterize the dynamical structure of stimulus-evoked processes ii) quantify the amount of information exchanged across cortical regions and iii) estimate the complexity of cerebral responses. At last, I show how a mathematical model based on Bayesian inference principles, can account for a large number of empirical findings observed in studies of conscious and unconscious perception. In a second part, I apply these methods on EEG recordings acquired from a large cohort of vegetative, minimally conscious and conscious patients. The results show that vegetative state patients present i) impaired late and sustained sound-evoked brain responses, ii) a reduction of the exchange of information across cortical regions iii) abnormal slow and medium EEG rhythms (<13Hz) and iv) a decrease of the EEG complexity. Ultimately, these various neural signatures of consciousness could be used in synergy to decode conscious contents and help to diagnose, predict and monitor the state of consciousness of non-communicating patients
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Cacciamani, Laura M. "Beyond Conscious Object Perception: Processing and Inhibition of the Groundside of a Figure." Diss., The University of Arizona, 2014. http://hdl.handle.net/10150/332846.
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Object perception is necessary to our understanding of the visual world, yet its neural mechanism remains poorly understood. The goal of this dissertation is to shed light on this mechanism. Current computational models of object perception suggest that regions on opposite sides of a shared border compete, with the winner perceived as the shaped object and the loser as its locally shapeless background (or ground). Recent behavioral work indicates that the result of this competition is suppression of the ground at the level of object shape--a finding not predicted by models. Here, I present three studies that extend this previous research on ground suppression as a mechanism by which object perception is accomplished. I first show that the amount of suppression applied to the ground depends on the amount of competition for object status (Salvagio, Cacciamani, & Peterson, 2012). I then provide the first neural evidence of ground suppression from shape-level competition at both high and low levels of the visual hierarchy, with the latter arising from top-down feedback (Cacciamani, Scalf, & Peterson, submitted). Finally, I show that semantic information pertaining to the ground is accessed prior to the assignment of object status, but unlike shape information, is not suppressed (Cacciamani, Mojica, Sanguinetti, & Peterson, 2014). Together, the three studies that comprise this dissertation demonstrate that ground suppression arising from shape-level competition underlies object perception. This research contradicts traditional theories stating that objects are processed unidirectionally through the visual system in a single feedforward pass; instead, it supports theories of object perception entailing dynamical feedforward and feedback processes.
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Madipakkam, Apoorva Rajiv [Verfasser]. "The conscious and unconscious processing of socially relevant visual stimuli / Apoorva Rajiv Madipakkam." Berlin : Medizinische Fakultät Charité - Universitätsmedizin Berlin, 2017. http://d-nb.info/1140486853/34.
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Cressman, Erin K. "How do "invisible" stimuli influence action? : Visuomotor processing in the absence of conscious awareness." Thesis, University of British Columbia, 2007. http://hdl.handle.net/2429/31278.
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The goal of the current research was to examine the properties of visuomotor processing occurring in the absence of conscious awareness. Specifically, we investigated the ability of a subliminal stimulus to influence the on-line control of an action (Studies 1 and 2) and the extent to which the same subliminal stimulus could influence action when the probability of it predicting the upcoming response was manipulated (Studies 3 and 4). In order to display stimuli subliminally, stimuli were presented through the psychophysical procedure of metacontrast masking - a form of backward masking in which the visibility of a briefly displayed visual stimulus (the prime ) is greatly reduced when it is followed by a second visual stimulus (the mask ). Thus in the present research we were interested in how the primes would influence performance. Results revealed that (1) unconscious visuomotor processing can result in the modification of an overt response, such that a goal-directed movement is adjusted in response to a subliminal stimulus and (2) the visuomotor system can be modified in response to manipulations of the prime-mask sequence presented at an unconscious level. These results imply that subliminal stimuli are not processed in a conditionally automatic manner. In order to explain the ability of subliminal stimuli to influence behaviour we propose an accumulator model, in which adaptations to the state of the system arising due to task constraints are reflected at the level of response activation (i.e. at the accumulators). An "accumulator" is tuned to a specific stimulus-response mapping such that if participants are instructed to make a left or right response, two separate accumulators are established with one collecting neural evidence for stimuli mapped to the left response and the other collecting neural evidence for stimuli mapped to the right response. Both primes and masks are equally effective at driving the accumulators and a response is initiated as soon as the accumulated neural evidence for one response versus the alternative response reaches a critical threshold. The level of this threshold can be set strategically, or modified without awareness, depending on the prime-mask sequence displayed.Education, Faculty of
Kinesiology, School of
Graduate
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Chang, Acer Yu-Chan. "The role of predictive processing in conscious access and regularity learning across sensory domains." Thesis, University of Sussex, 2017. http://sro.sussex.ac.uk/id/eprint/70234/.
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To increase fitness for survival, organisms not only passively react to environmental changes but also actively predict future events to prepare for potential hazards within their environment. Accumulating evidence indicates that the human brain is a remarkable predictive machine which constantly models causal relationships and predicts future events. This ‘predictive processing' framework, a prediction-based form of Bayesian inference, states that the brain continuously generates and updates predictions about incoming sensory signals. This framework has been showing notable explanatory power in understanding the mechanisms behind both human behaviour and neurophysiological data and elegantly specifies the underlying computational principles of the neural system. However, even though predictive processing has the potential to provide a unified theory of the brain (Karl Friston, 2010), we still have a limited understanding about fundamental aspects of this model, such as how it deals with different types of information, learns statistical regularities and perhaps most fundamentally of all what its relationship to conscious experience is. This thesis aims to investigate the major gaps in our current understanding of the predictive processing framework via a series of studies. Study 1 investigated the fundamental relationship between unconscious statistical inference reflected by predictive processing and conscious access. It demonstrated that predictions that are in line with sensory evidence accelerate conscious access. Study 2 investigated how low level information within the sensory hierarchy is dealt with by predictive processing and regularity learning mechanisms through “perceptual echo” in which the cross-correlation between a sequence of randomly fluctuating luminance values and occipital electrophysiological (EEG) signals exhibits a long-lasting periodic (~100ms cycle) reverberation of the input stimulus. This study identified a new form of regularity learning and the results demonstrate that the perceptual echo may reflect an iterative learning process, governed by predictive processing. Study 3 investigated how supra-modal predictive processing is capable of learning regularities of temporal duration and also temporal predictions about future events. This study revealed a supramodal temporal prediction mechanism which processes auditory and visual temporal information and integrates information from the duration and rhythmic structures of events. Together these studies provide a global picture of predictive processing and regularity learning across differing types of predictive information.
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Liu, Feilong. "Accelerating Analytical Query Processing with Data Placement Conscious Optimization and RDMA-aware Query Execution." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1543532295915722.
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Smith, Ryan Scott. "Disambiguating the Roles of Select Medial Prefrontal Subregions in Conscious and Unconscious Emotional Processing." Diss., The University of Arizona, 2015. http://hdl.handle.net/10150/556440.
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A substantial body of previous research suggests that the medial prefrontal cortex (MPFC) plays an important role in multiple aspects of emotion. These aspects include, but are not limited to, (1) generating, (2) experiencing, and (3) regulating one's own emotional state, as well as (4) facilitating the use of emotion-related information within goal-directed cognition and action selection. However, there is considerable controversy with regard to the distinct functional roles of various MPFC subregions. In this dissertation, I first provide a review of the theoretical and experimental literature to date in order to defend a plausible model of the hierarchical neural processes associated with each of the aspects of emotion highlighted above. This model proposes that different MPFC subregions each play distinct, but interactive, roles at or near the top of the respective hierarchical systems associated with those aspects of emotion. After reviewing this model, I then provide a description of four experiments that test the predictions of this model's claims regarding the roles of three distinct MPFC subregions: the rostral anterior cingulate cortex (rACC), the dorsomedial prefrontal cortex (DMPFC), and the ventromedial prefrontal cortex (VMPFC). These experiments provide independent support for the claims that (1) rACC plays an important role in representing the conceptual meaning of one's felt emotional reactions, (2) DMPFC plays an important role in maintaining representations of one's own emotions within a consciously accessible state, and (3) VMPFC plays an important role in both appraising the emotional significance of one's current situation and triggering the somatic/visceral reactions associated with the generation of an emotional response. In the concluding section of the dissertation, I then integrate these findings together with the larger model and discuss important directions for future research as well as ways in which the model might be extended to include insights from recent advances in theoretical neuroscience associated with predictive coding.
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Schwalb, David, Jens Krüger, and Hasso Plattner. "Cache conscious column organization in in-memory column stores." Universität Potsdam, 2013. http://opus.kobv.de/ubp/volltexte/2013/6389/.
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Cost models are an essential part of database systems, as they are the basis of query performance optimization. Based on predictions made by cost models, the fastest query execution plan can be chosen and executed or algorithms can be tuned and optimised. In-memory databases shifts the focus from disk to main memory accesses and CPU costs, compared to disk based systems where input and output costs dominate the overall costs and other processing costs are often neglected. However, modelling memory accesses is fundamentally different and common models do not apply anymore.
This work presents a detailed parameter evaluation for the plan operators scan with equality selection, scan with range selection, positional lookup and insert in in-memory column stores. Based on this evaluation, a cost model based on cache misses for estimating the runtime of the considered plan operators using different data structures is developed. Considered are uncompressed columns, bit compressed and dictionary encoded columns with sorted and unsorted dictionaries. Furthermore, tree indices on the columns and dictionaries are discussed. Finally, partitioned columns consisting of one partition with a sorted and one with an unsorted dictionary are investigated. New values are inserted in the unsorted dictionary partition and moved periodically by a merge process to the sorted partition. An efficient attribute merge algorithm is described, supporting the update performance required to run enterprise applications on read-optimised databases. Further, a memory traffic based cost model for the merge process is provided.Kostenmodelle sind ein essentieller Teil von Datenbanksystemen und bilden die Basis für Optimierungen von Ausführungsplänen. Durch Abschätzungen der Kosten können die entsprechend schnellsten Operatoren und Algorithmen zur Abarbeitung einer Anfrage ausgewählt und ausgeführt werden. Hauptspeicherresidente Datenbanken verschieben den Fokus von I/O Operationen hin zu Zugriffen auf den Hauptspeicher und CPU Kosten, verglichen zu Datenbanken deren primäre Kopie der Daten auf Sekundärspeicher liegt und deren Kostenmodelle sich in der Regel auf die kostendominierenden Zugriffe auf das Sekundärmedium beschränken. Kostenmodelle für Zugriffe auf Hauptspeicher unterscheiden sich jedoch fundamental von Kostenmodellen für Systeme basierend auf Festplatten, so dass alte Modelle nicht mehr greifen. Diese Arbeit präsentiert eine detaillierte Parameterdiskussion, sowie ein Kostenmodell basierend auf Cache-Zugriffen zum Abschätzen der Laufzeit von Datenbankoperatoren in spaltenorientierten und hauptspeicherresidenten Datenbanken wie das Selektieren von Werten einer Spalte mittels einer Gleichheitsbedingung oder eines Wertebereichs, das Nachschlagen der Werte einzelner Positionen oder dem Hinzufügen neuer Werte. Dabei werden Kostenfunktionen für die Operatoren erstellt, welche auf unkomprimierten Spalten, mittels Substitutionskompression komprimierten Spalten sowie bit-komprimierten Spalten operieren. Des Weiteren werden Baumstrukturen als Index Strukturen auf Spalten und Wörterbüchern in die Betrachtung gezogen. Abschließend werden partitionierte Spalten eingeführt, welche aus einer lese- und einer schreib-optimierten Partition bestehen. Neu Werte werden in die schreiboptimierte Partition eingefügt und periodisch von einem Attribut-Merge-Prozess mit der leseoptimierten Partition zusammengeführt. Beschrieben wird eine Effiziente Implementierung für den Attribut-Merge-Prozess und ein Hauptspeicher-bandbreitenbasiertes Kostenmodell aufgestellt.
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Shirazibeheshti, Amirali. "The effect of sedation on conscious processing : computational analysis of the EEG response to auditory irregularity." Thesis, University of Kent, 2015. https://kar.kent.ac.uk/54467/.
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Characterising the relationships between conscious and unconscious processes is one of the most important goals in cognitive neuroscience. Behavioural studies as well as neuroimaging techniques have been conducted to understand the nature of conscious perception in the brain. Functional brain imaging and EEG (Electroencephalogram) methods allow for detailed exploration of neural and computational correlates of conscious and unconscious cognition. Using a high density EEG dataset, recorded from 129 electrodes over the scalp, we studied the neural responses of the brain to auditory stimuli. To this end, we employed an auditory oddball paradigm, called the local-global experiment. Bekinschtein et al (2009) designed this experiment to explore the neural dynamics at the early auditory cortex, associated with the MMN (mismatch negativity) component, generated by the local violation of auditory stimuli. They also investigated a later novelty response, associated with the P3 (a late positive response) component, which was generated by the global violation of auditory stimuli. Their findings suggest that the global response, corresponding to working memory updating, independently from the local response, is a signature of conscious processing. But our investigations shows that the local and global effects are not fully independent from one another. Therefore, we looked for other potential signatures of conscious processing. To do this, we studied 18 healthy participants who had been sedated. Using SPM (Statistical Parametric Mapping), which is a mass univariate approach, we analysed the sedation dataset in an omnibus statistical setting. We found an interaction between the local and global effects. In addition, we investigated the impact of sedation on both the early and late temporal components (i.e. the local and global effects), and their interaction. In addition to SPM analysis, we performed single-trial analysis. Unlike SPM analysis, which explores ERPs (average effect across replications) to assess significance, single-trial analysis looks for variation across replications, from one experimental level to another. More specifically, we looked at amplitude variation and temporal jitter when participants are sedated versus recovered. In the cases, when the null hypothesis is not rejected (i.e. there is no significant difference across different levels), we calculated Bayes factors to search for evidence in favour of the null hypothesis. With the exception of latency dispersion under dual (global and local) deviance, we could find no evidence for increased variability in single trial responses under sedation. This suggests the effects of reduced conscious level are systematic and can be summarised as an attenuation of dependency of (or interaction between) local and global processing.
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Cooke, Jennifer Ann. "Interacting with consciousness : an investigation into the neural signatures of conscious processing using the global-local auditory task." Thesis, University of Kent, 2016. https://kar.kent.ac.uk/63872/.
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Can conscious processing be inferred from electrophysiological measurements? Bekinschtein et al. (2009) devised the global-local auditory oddball task as a way of investigating electrophysiological (EEG) responses to hierarchical violations in auditory regularity. It was argued that the detection of local violations in auditory regularity (arising within a short temporal window) occurs independently of consciousness, whilst the detection of global violations in auditory regularity (arising within a longer temporal window) occurs only with the presence of consciousness. For this to be the case, global and local effects must be assumed to be independent and thus share an additive relationship. Crucially, if a relationship is additive, then cognitive subtraction allows each effect to be understood in isolation. Within this thesis, we explore the notion that global and local effects may not be independent but actually share a multiplicative relationship, based on the principle that the brain is a non-linear system (Friston et al., 1996). We examine this by re-analysing the data of the original attention study by Bekinschtein et al. (2009) using a factorial design analysis. What is more, we extend this work to consider the presence of an interaction between global and local effects when consciousness is manipulated using healthy sedation. Our findings reveal an interaction between global and local effects that occurs within the region of the global effect and varies depending on the presence of direct attention, expectancy and sedation. The manifestation of an interaction between global and local effects is discussed in detail in relation to a predictive coding framework, whereby multiple levels of prediction exist within the brain (Auksztulewicz & Friston, 2015). Furthered analysis, directly comparing the findings of varied attention to the findings with healthy sedation is presented and discussed with a view to the brain's predictive nature. Methodological issues that were encountered, as well as a method we developed for re-aligning time-series data, are presented and explored in detail within the later Chapters of this thesis. Our research suggests that global and local effects may not be considered as independent and therefore the presence of a global effect is not sufficient to constitute a functionally isolated marker of conscious processing (as initially proposed by Bekinschtein et al. [2009]). Further research is necessary to better define the nature of an interaction between global and local effects in relation to conscious experience.
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Rousseau, Noel. "Conscious processing of a complex motor skill : an investigation into the automaticity paradigm of full golf swing execution." Thesis, University of Birmingham, 2015. http://etheses.bham.ac.uk//id/eprint/6359/.
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This thesis examines factors that influence the propensity to, and the utility of, conscious processing during a complex motor skill. Prevalent theories of skill acquisition and automaticity view expert performance as best executed in the absence of conscious control of the movement. There is substantial evidence to support this claim for simple tasks but a lack of research for complex skills is apparent. In this thesis the role of conscious processing (reinvestment) is examined in relation to the full golf swing in baseline and anxiety conditions. The early experiments in the thesis examined the effects of limiting conscious processing through a temporal restriction. This paved the way for the later experiments that looked deeper into individualistic elements of personality and cognitive 'make up,' that may affect the control structures of the golf swing. The results indicate that conscious processing during task performance affects individuals differently. A high 'verbaliser' group deteriorated while 'visualisers' showed improvement during restricted conscious input trials. Furthermore, both short-term memory and working memory showed positive correlations with task performance. Overall, this study implies a positive role for conscious control in the golf swing and questions the efficacy of reinvestment theory in relation to complex skills.
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Eriksson, Johan. "The conscious brain : Empirical investigations of the neural correlates of perceptual awareness." Doctoral thesis, Umeå : Department of Psychology, Umeå University, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-1430.
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Quevedo, Díaz Marcos 1979. "Role of the amygdala and the hippocampus in conscious perception and emotion processing in patients with drug resistant epilepsy." Doctoral thesis, Universitat Pompeu Fabra, 2017. http://hdl.handle.net/10803/664168.
Full textAbstract:
Understanding the neural basis of conscious perception is still one of the central
unsolved problems in neuroscience. Current theoretical models of conscious
processing include the Global Workspace Theory, that proposes that for any
stimulus to access to consciousness it should be broadcasted to different brain
areas, making information, simultaneous and globally available among distant
nodes in the network, through a network of neurons with long-range axons
densely distributed in prefrontal, parieto-temporal, and cingulate cortices.
Specifically, the hippocampus has been postulated as a critical hub, given its
large structural and functional connectivity with distant brain areas.
In this Thesis, I have taken advantage of the high spatial precision and signal-tonoise
ratio afforded by intracranial recording in epileptic patients to explore
signatures of this state of distributed ‘‘ignition’’ in two structures of the limbic
system, the hippocampus and the amygdala. Electrophysiological data were
recorded during the performance of two cognitive tasks for emotion recognition
of faces (Emotion Recognition Test) and conscious perception of threatening
words (Significant Words Paradigm). Specifically, I contrasted the fate of masked
(subliminal) versus unmasked (conscious) words while recording from local sites
in amygdala and hippocampus, using intracerebral depth electrodes in four
epileptic patients. We explored two signatures of conscious processing: event
related potentials (ERPs) and event related spectral perturbations (ERSPs)
modifications discriminating emotion-related information (faces and words) and
consciously perceived from subliminally processed stimuli.
The analysis of the neuropsychological tests revealed a significant emotionspecific
impairment in emotion recognition of faces, but no deficit was detected
for perceiving emotion content of words in patients with epilepsy. ERP and ERSP
analyses showed that amygdala, but not hippocampus has a role for emotion
processing disregarding the quality of stimuli (faces or words); importantly, this
was also observed in subliminal condition. On the other hand, when comparing
conscious against subliminally perceived words, ERP and ERSP showed that
amygdala and hippocampus are similarly involved in conscious processing;
specifically, significant changes in voltage (ERP) and in theta and gamma
frequencies (ERSP) were noted around 500 ms after target onset, supporting that
conscious processing occurs between an early-perceptual window (0-200ms)
and a later window in which more complex processing occurs (600-800ms). We
conclude that those changes might constitute different measures of the same
state of distributed ‘‘ignition’’ of a larger cortical network.Entender los mecanismos neuronales que dan lugar a la percepción consciente es todavía uno de los grandes problemas por resolver en neurociencia. Actualmente, los modelos teóricos sobre la consciencia incluyen la Teoría del Espacio de Trabajo Global, la cual propone que para que un estímulo acceda a la consciencia, éste debe ser transmitido a diferentes áreas cerebrales, de tal forma que su información esté disponible global y simultáneamente entre todos los nodos distantes que componen esa red, a través de una red de neuronas con axones de largo alcance densamente distribuidos entre las cortezas prefrontal, parietofrontal y cingulada. Específicamente el hipocampo ha sido propuesto como un nodo crítico, debido a sus numerosas conexiones estructurales y funcionales con regiones cerebrales distantes. En esta Tesis, he aprovechado la alta precisión espacial y relación señal-ruido que brindan los registros intracraneal en pacientes epilépticos, con el fin de explorar las firmas de este estado de “ignición” distribuida, desde dos estructuras del sistema límbico: el hipocampo y la amígdala, involucrados en el procesamiento de estímulos emocionales. Los datos electrofisiológicos fueron registrados durante la realización de dos tareas cognitivas de reconocimiento emocional de caras (Tarea de Reconocimiento de Emociones) y de palabras amenazantes (Paradigma de Palabras Significativas). Específicamente, contrasté el destino de registros de palabras enmascaradas (subliminales) versus no-enmascaradas (conscientes) mientras se registraban un sitiosl locales de amígdala e hipocampo en cuatro pacientes epilépticos. Exploramos las firmas del procesamiento consciente con: potenciales relacionados a evento (ERP) y perturbaciones espectrales relacionadas a evento (ERSP) en el hipocampo (theta) y en la amígdala (gamma) que discriminan entre estímulos emocionales conscientemente percibidos de aquellos procesados subliminalmente. El análisis de las pruebas neuropsicológicas reveló que los pacientes con epilepsia tienen una alteración significativa emoción-específica en el reconocimiento emocional de caras, pero ningún déficit en el reconocimiento de palabras. El análisis de ERP y ERSP mostró que la amígdala, pero no el hipocampo, tiene un papel en el procesamiento emocional independientemente de la calidad del estímulo (caras o palabras); importantemente, esto también fue observado en la condición subliminal. Por otro lado, cuando comparamos las palabras percibidas conscientemente contra aquellas percibidas subliminalmente, tanto los ERPS como los ERSP mostraron que la amígdala y el hipocampo están involucrados de manera similar en el procesamiento de la consciencia; específicamente, se observaron cambios significativos en el voltaje (ERP) y en frecuencias theta y gamma (ERSP) alrededor de 500ms después de la presentación del estímulo. Lo anterior apoya la idea que el procesamiento de la consciencia ocurre en una ventana temporal intermedia entre la percepción temprana (0-200ms) y un procesamiento cognitivo más complejo y tardío (600- 800ms). Concluimos que estos cambios pueden constituir diferentes medidas de un mismo estado de “ignición” distribuida de una red cortical más grande.
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Haertel, Robbie A. "Practical Cost-Conscious Active Learning for Data Annotation in Annotator-Initiated Environments." BYU ScholarsArchive, 2013. https://scholarsarchive.byu.edu/etd/4242.
Full textAbstract:
Many projects exist whose purpose is to augment raw data with annotations that increase the usefulness of the data. The number of these projects is rapidly growing and in the age of “big data” the amount of data to be annotated is likewise growing within each project. One common use of such data is in supervised machine learning, which requires labeled data to train a predictive model. Annotation is often a very expensive proposition, particularly for structured data. The purpose of this dissertation is to explore methods of reducing the cost of creating such data sets, including annotated text corpora.We focus on active learning to address the annotation problem. Active learning employs models trained using machine learning to identify instances in the data that are most informative and least costly. We introduce novel techniques for adapting vanilla active learning to situations wherein data instances are of varying benefit and cost, annotators request work “on-demand,” and there are multiple, fallible annotators of differing levels of accuracy and cost. In order to account for data instances of varying cost, we build a model of cost from real annotation data based on a user study. We also introduce a novel cost-conscious active learning algorithm which we call return-on-investment, that selects instances for annotation that contain the most benefit per unit cost. To address the issue of annotators that request instances “on-demand,” we develop a parallel, “no-wait” framework that performs computation while the annotator is annotating. As a result, annotators need not wait for the computer to determine the best instance for them to annotate—a common problem with existing approaches. Finally, we introduce a Bayesian model designed to simultaneously infer ground truth annotations from noisy annotations, infer each individual annotators accuracy, and predict its own accuracy on unseen data, without the use of a held-out set. We extend ROI-based active learning and our annotation framework to handle multiple annotators using this model. As a whole, our work shows that the techniques introduced in this dissertation reduce the cost of annotation in scenarios that are more true-to-life than previous research.
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Hasford, Jonathan. "To Think or Not to Think?: A New Perspective on Optimal Consumer Decision Making." UKnowledge, 2013. http://uknowledge.uky.edu/marketing_etds/1.
Full textAbstract:
This research introduces a new theoretical perspective (termed the Adaptive Processing Perspective) that reexamines how consumers should think before making decisions and the optimal outcomes that result. New insights into conscious (“careful deliberation”), unconscious (“sleeping on it”), and intuitive (“going with your gut”) thought processes are provided. Across four studies, empirical evidence demonstrates that consumers can make significantly better decisions by thinking more about routine choices, using their intuition for occasional purchase decisions, and distracting themselves before making major purchase decisions. Specifically, in study 1, increased conscious thought optimized routine decision making due to increases in openness to information. In study 2, consumers using intuition optimized an occasional purchase decision by focusing attention on relevant information. Study 3 demonstrated unconscious thought to be optimal for consumers when making a major purchase decision via their engagement in associative processing. Lastly, study 4 provided further support for the Adaptive Processing Perspective by manipulating the decision setting (i.e., routine, limited, extensive) across a common product and replicating the earlier study results. Several theoretical and practical advances to the domains of information processing and consumer decision making are offered and discussed.
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Pohl, Constantin [Verfasser], Kai-Uwe [Akademischer Betreuer] Sattler, Klaus [Gutachter] Meyer-Wegener, and Gunter [Gutachter] Saake. "Hardware-conscious query processing for the many-core era / Constantin Pohl ; Gutachter: Klaus Meyer-Wegener, Gunter Saake ; Betreuer: Kai-Uwe Sattler." Ilmenau : TU Ilmenau, 2020. http://d-nb.info/1221960393/34.
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Adams, Danielle. "Exploring the attentional processes of expert performers and the impact of priming on motor skill execution." Thesis, Brunel University, 2010. http://bura.brunel.ac.uk/handle/2438/5082.
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It is widely acknowledged that under situations of heightened pressure, many expert athletes suffer from performance decrements. This phenomenon has been termed ‘choking under pressure’ and has been the subject of extensive research in sport psychology. Despite this attention, gaps in the literature remain leaving opportunities for further advancements in knowledge about the phenomenon, particularly in relation to its underlying processes and the development of appropriate interventions that can be adopted in order to alleviate, or even prevent choking. The present programme of research, in general terms, aimed to develop and test the efficacy of an intervention tool, based on priming, to alleviate choking under pressure. It was acknowledged that such a tool should be matched to the mechanisms that underlie the choking process and although an abundance of research has provided valuable information about these mechanisms, it was identified that there still remains a lack of consensus regarding the most appropriate explanatory theory. Therefore the initial study in this thesis aimed to provide further insight into the processes that govern choking by examining accounts from elite international swimmers of their experiences of performing under high levels of pressure. The results provided further support for the postulation that choking under pressure occurs as a result of a combination of conscious processing hypothesis (Masters, 1992) and processing efficiency theory (Eysenck & Calvo, 1992) and that an optimum level of skill-focused attention is beneficial to performance. The following studies utilised this information as well as that of the existent theories of choking, to develop and examine an effective priming based intervention tool (a scrambled sentence task). Specifically, Studies 2, 3 and 4 examined the amount of residual working memory available after activation of the prime, the optimisation of the priming task and the efficacy of the tool in promoting performance under high pressure respectively. Results revealed support for the efficacy of the tool in reducing online skill-focused attention and promoting performance under both low- and high-pressure conditions. Finally, the general themes that emerged throughout the whole programme of study are discussed, as well as the limitations and recommendations for future research. Implications for coaches, athletes and practitioners are also presented.
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López, Álvarez David. "Recursos anchos: una técnica de bajo coste para explotar paralelismo agresivo en códigos numéricos." Doctoral thesis, Universitat Politècnica de Catalunya, 1998. http://hdl.handle.net/10803/5997.
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Els bucles son la part que més temps consumeix en les aplicacions numèriques. El rendiment dels bucles està limitat tant pels recursos oferts per l'arquitectura com per les recurrències del bucle en la computació. Per executar més operacions per cicle, els processadors actuals es dissenyen amb graus creixents de replicació de recursos (tècnica de replicació) para ports de memòria i unitats funcionals. En canvi, el gran cost en termes d'àrea i temps de cicle d'aquesta tècnica limita tenir alts graus de replicació: alts valors en temps de cicle contraresten els guanys deguts al decrement en el nombre de cicles, mentre que alts valors en l'àrea requerida poden portar a configuracions impossibles d'implementar. Una alternativa a la replicació de recursos, és fer los més amples (tècnica que anomenem "widening"), i que ha estat usada en alguns dissenys recents. Amb aquesta tècnica, l'amplitud dels recursos s'amplia, fent una mateixa operació sobre múltiples dades.
Per altra banda, alguns microprocessadors escalars de propòsit general han estat implementats amb unitats de coma flotants que implementen la instrucció sumar i multiplicar unificada (tècnica de fusió), el que redueix la latència de la operació combinada, tanmateix com el nombre de recursos utilitzats.
A aquest treball s'avaluen un ampli conjunt d'alternatives de disseny de processadors VLIW que combinen les tres tècniques. S'efectua una projecció tecnològica de les noves generacions de processadors per predir les possibles alternatives implementables. Com a conclusió, demostrem que tenint en compte el cost, combinar certs graus de replicació i "widening" als recursos hardware és més efectiu que aplicar únicament replicació. Així mateix, confirmem que fer servir unitats que fusionen multiplicació i suma pot tenir un impacte molt significatiu en l'increment de rendiment en futures arquitectures de processadors a un cost molt raonable.
Loops are the main time-consuming part of numerical applications. The performance of the loops is limited either by the resources offered by the architecture or by recurrences in the computation. To execute more operations per cycle, current processors are designed with growing degrees of resource replication (replication technique) for memory ports and functional units. However, the high cost in terms of area and cycle time of this technique precludes the use of high degrees of replication. High values for the cycle time may clearly offset any gain in terms of number of execution cycles. High values for the area may lead to an unimplementable configuration. An alternative to resource replication is resource widening (widening technique), which has also been used in some recent designs in which the width of the resources is increased (i.e., a single operation is performed over multiple data). Moreover, several general-purpose superscalar microprocessors have been implemented with multiply-add fused floating point units (fusion technique), which reduces the latency of the combined operation and the number of resources used. On this thesis, we evaluate a broad set of VLIW processor design alternatives that combine the three techniques. We perform a technological projection for the next processor generations in order to foresee the possible implementable alternatives. From this study, we conclude that if the cost is taken into account, combining certain degrees of replication and widening in the hardware resources is more effective than applying only replication. Also, we confirm that multiply-add fused units will have a significant impact in raising the performance of future processor architectures with a reasonable increase in cost.
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Ampatzis, Christos. "On the evolution of autonomous decision-making and communication in collective robotics." Doctoral thesis, Universite Libre de Bruxelles, 2008. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210445.
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In this thesis, we use evolutionary robotics techniques to automatically design and synthesisebehaviour for groups of simulated and real robots. Our contribution will be on
the design of non-trivial individual and collective behaviour; decisions about solitary or
social behaviour will be temporal and they will be interdependent with communicative
acts. In particular, we study time-based decision-making in a social context: how the
experiences of robots unfold in time and how these experiences influence their interaction
with the rest of the group. We propose three experiments based on non-trivial real-world
cooperative scenarios. First, we study social cooperative categorisation; signalling and
communication evolve in a task where the cooperation among robots is not a priori required.
The communication and categorisation skills of the robots are co-evolved from
scratch, and the emerging time-dependent individual and social behaviour are successfully
tested on real robots. Second, we show on real hardware evidence of the success of evolved
neuro-controllers when controlling two autonomous robots that have to grip each other
(autonomously self-assemble). Our experiment constitutes the first fully evolved approach
on such a task that requires sophisticated and fine sensory-motor coordination, and it
highlights the minimal conditions to achieve assembly in autonomous robots by reducing
the assumptions a priori made by the experimenter to a functional minimum. Third, we
present the first work in the literature to deal with the design of homogeneous control
mechanisms for morphologically heterogeneous robots, that is, robots that do not share
the same hardware characteristics. We show how artificial evolution designs individual
behaviours and communication protocols that allow the cooperation between robots of
different types, by using dynamical neural networks that specialise on-line, depending on
the nature of the morphology of each robot. The experiments briefly described above
contribute to the advancement of the state of the art in evolving neuro-controllers for
collective robotics both from an application-oriented, engineering point of view, as well as
from a more theoretical point of view.
Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished
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CUCCHIARINI, VERONICA. "L'esplorazione dei processi mentali implicati nella soluzione di problemi insight attraverso lo studio del controverso ruolo della working memory." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2020. http://hdl.handle.net/10281/273359.
Full textAbstract:
L’insight problem solving è una delle attività cognitive più affascinanti, alla base della scoperta scientifica, della creatività e dell’innovazione. Nonostante la grande attenzione che ha ricevuto il concetto di insight nel corso del tempo e l’ampio corpus di ricerche accumulate, i processi implicati nella soluzione dei problemi di tipo insight rimangono in parte “misteriosi”. Questo lavoro cercherà di far emergere gli aspetti interessanti e i punti critici delle principali prospettive teoriche che si occupano di studiare questi processi, attraverso tre studi. Il filo conduttore che unisce gli studi è l'esplorazione del ruolo della memoria di lavoro nell'insight problem solving come strumento per far luce sulla natura conscia o inconscia dei processi implicati nella soluzione di questo tipo di processi. Il primo studio riguarda la relazione tra le funzioni dominio-generali della memoria di lavoro, intese come controllo esecutivo, e la soluzione dei problemi insight in una condizione a tempo limitato e in seguito a un periodo di incubazione indotto. Il secondo studio indaga la possibilità di considerare ruoli separati per le componenti dominio-specifiche verbali vs. spaziali della memoria di lavoro nell’insight problem solving, che si ipotizza potrebbero influenzare in maniera opposta il processo di soluzione. Il terzo studio infine, approfondisce la relazione tra strategie di soluzione, cambi di rappresentazione e differenze individuali nella Working Memory Capacity. Gli esperimenti hanno mostrato che i processi di soluzione dei problemi insight differiscono da quelli dei problemi non insight, non solo per la loro natura inconscia, ma anche per alcuni fattori che caratterizzano più in generale l’insight problem solving, come ad esempio le caratteristiche del problema, le conoscenze implicite dei soggetti e una più globale interpretazione della situazione sperimentale.Insight problem solving is one of the most fascinating cognitive activities, underlying scientific discovery, creativity and innovation. Despite the great attention that the concept of insight has received and the large body of research, the processes involved in the solution of this type of problem remain in part “mysterious”. This work, consisting of three studies, will seek to highlight the interesting aspects and the critical points of the main theoretical perspectives concerning the study of these processes. The common thread that unites the studies is the exploration of the role of working memory in insight problem solving as a tool to shed light on the conscious or unconscious nature of the processes involved in the solution of this type of problem. The first study concerns the relationship between the general-domain functions of working memory, understood as executive control, and the solution of insight problems in a limited time condition and after an induced incubation period. The second study explores the possibility of considering separate roles for verbal vs spatial specific-domain components of working memory in insight problem solving, which are assumed to affect the solution process in opposite ways. Finally, the third study explores the relationship between solution strategies, representation changes and individual differences in Working Memory Capacity. Experiments show that the processes underlying the solution of insight problems differ from those of non-insight problems, not only for their unconscious nature, but also for some factors that characterize more generally the insight problem solving, such as the characteristics of the problem, the implicit knowledge of the subjects and a more global interpretation of the experimental situation.
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Willenbockel, Verena. "Visual information processing during conscious and non-conscious face perception." Thèse, 2012. http://hdl.handle.net/1866/10095.
Full textAbstract:
Les stimuli naturels projetés sur nos rétines nous fournissent de l’information visuelle riche. Cette information varie le long de propriétés de « bas niveau » telles que la luminance, le contraste, et les fréquences spatiales. Alors qu’une partie de cette information atteint notre conscience, une autre partie est traitée dans le cerveau sans que nous en soyons conscients. Les propriétés de l’information influençant l’activité cérébrale et le comportement de manière consciente versus non-consciente demeurent toutefois peu connues. Cette question a été examinée dans les deux derniers articles de la présente thèse, en exploitant les techniques psychophysiques développées dans les deux premiers articles.
Le premier article présente la boîte à outils SHINE (spectrum, histogram, and intensity normalization and equalization), développée afin de permettre le contrôle des propriétés de bas niveau de l'image dans MATLAB. Le deuxième article décrit et valide la technique dite des bulles fréquentielles, qui a été utilisée tout au long des études de cette thèse pour révéler les fréquences spatiales utilisées dans diverses tâches de perception des visages. Cette technique offre les avantages d’une haute résolution au niveau des fréquences spatiales ainsi que d’un faible biais expérimental. Le troisième et le quatrième article portent sur le traitement des fréquences spatiales en fonction de la conscience. Dans le premier cas, la méthode des bulles fréquentielles a été utilisée avec l'amorçage par répétition masquée dans le but d’identifier les fréquences spatiales corrélées avec les réponses comportementales des observateurs lors de la perception du genre de visages présentés de façon consciente versus non-consciente. Les résultats montrent que les mêmes fréquences spatiales influencent de façon significative les temps de réponse dans les deux conditions de conscience, mais dans des sens opposés. Dans le dernier article, la méthode des bulles fréquentielles a été combinée à des enregistrements intracrâniens et au Continuous Flash Suppression (Tsuchiya & Koch, 2005), dans le but de cartographier les fréquences spatiales qui modulent l'activation de structures spécifiques du cerveau (l'insula et l'amygdale) lors de la perception consciente versus non-consciente des expressions faciales émotionnelles. Dans les deux régions, les résultats montrent que la perception non-consciente s'effectue plus rapidement et s’appuie davantage sur les basses fréquences spatiales que la perception consciente.
La contribution de cette thèse est donc double. D’une part, des contributions méthodologiques à la recherche en perception visuelle sont apportées par l'introduction de la boîte à outils SHINE ainsi que de la technique des bulles fréquentielles. D’autre part, des indications sur les « corrélats de la conscience » sont fournies à l’aide de deux approches différentes.Natural stimuli impinging on our retinas provide us with a wealth of visual information. This information varies along “low-level” features, such as luminance, contrast, and spatial frequency (SF). Whereas some of this information reaches our awareness, some of it is processed in the brain without us ever becoming aware of it (i.e., non-consciously). A remaining question is precisely which SFs influence brain activation and behavior consciously vs. non-consciously. The aim of this thesis was to address this question using state-of the-art psychophysical techniques. The first article introduces the SHINE (spectrum, histogram, and intensity normalization and equalization) toolbox for controlling low-level image properties in MATLAB. The second article describes and validates the SF Bubbles technique, which was used throughout the studies in this thesis to map SF tuning for various face perception tasks with a high SF resolution and low experimental bias. The third and fourth articles focus on SF processing as a function of awareness. In the former, SF Bubbles was employed together with repetition priming and masking to investigate which SFs are correlated with observers’ behavioral responses during conscious vs. non-conscious face-gender perception. The results show that the same SFs significantly influenced response times in both prime awareness conditions but, surprisingly, in opposite ways. In the latter, SF Bubbles was combined with intracranial recordings from awake human patients and Continuous Flash Suppression (Tsuchiya & Koch, 2005). This allowed us to map the SFs that modulate activation in specific brain structures (the insula and the amygdala) during the conscious vs. non-conscious perception of emotional facial expressions. The results for both regions demonstrate that non-conscious perception relied on low SFs more and was faster than conscious perception. The contribution made in this thesis is thus two-fold: methodological contributions to visual perception research are made by introducing the SHINE toolbox and the SF Bubbles technique, and insights into the “informational correlates” of consciousness are provided from two different angles.
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Ventura, Ana Sofia Tavares da Silva Marques. "Exploring unconscious threat processing using virtual reality." Master's thesis, 2021. http://hdl.handle.net/10773/31571.
Full textAbstract:
Emotions have as primary effect the activation of our body to elicite a quick
response. Fear responses created mechanisms to avoid or escape threatening
stimuli and events. Through natural selection, the individuals with more
effective defensive and visual systems in responding and detecting threat,
prevailed. This processing advantage is still present in humans as various
studies reveal snakes’ advantage in accessing awareness. Continuous Flash
Suppression (CFS) technique allows the study of unawareness processing. In
this project, we will compare the results of using CFS in a computer monitor or
in a virtual reality device, accessing reaction times, heart rate and skin
conductance. To the dominant eye will been presented the stimuli (snakes’ or
birds’ images) and to the other eye the Mondrian masks. We will manipulate
the stimuli position by visions (foveal or peripheral). We expect advantage of
snakes’ stimuli over birds’ images, in both devices, and also modulation of the
physiological measures upon appearance of the threat eliciting stimuli. We
expect, as well, that snakes’ advantage will be independent of the visual field.
This project aims to contribute to the study of threat processing in the human
being as well as to evaluate the use of virtual reality in experimental psychology
and increase the ecological validity of its use in investigation and psychological
intervention.As emoções têm como efeito primário a ativação do nosso corpo para provocar uma resposta rápida. As respostas de medo criam mecanismos para evitar e escapar de estímulos e eventos ameaçadores. Através da seleção natural, os indivíduos com sistemas defensivos e visuais mais eficazes na resposta e deteção de ameaça, prevaleceram. Esta vantagem de processamento está ainda presente nos seres humanos de hoje, com vários estudos a mostrarem a vantagem das cobras na sua deteção e acesso à consciência. A técnica de CFS (Continuous Flash Supression) permite o estudo do processamento inconsciente. Neste projeto, iremos comparar os resultados usando CFS num monitor de computador e num dispositivo de realidade virtual, medindo tempos de reação, frequência cardíaca e condutância da pele. No olho dominante serão apresentados os estímulos (imagens de cobras e de pássaros) e no outro olho, as máscaras de Mondrian. Iremos manipular a posição dos estímulos através das visões (foveal e periférica). Esperamos uma vantagem dos estímulos de cobras aos dos pássaros, nas duas condições (computador e realidade virtual), e também modulação das medidas fisiológicas com o aparecimento dos estímulos ameaçadores. Esperamos também que a vantagem das cobras seja independente do campo visual. Este projeto pretende contribuir para o estudo do processamento de ameaça no ser humano, assim como avaliar o uso de realidade virtual em psicologia experimental e aumentar a validade ecológica do uso desta em investigação e intervenção psicológica.
Mestrado em Psicologia da Saúde e Reabilitação Neuropsicológica
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Kleinot, Karen Deborah. "A study in problem solving in the engineering sciences." Diss., 2004. http://hdl.handle.net/2263/27783.
Full textAbstract:
This study investigated the link between creative thought and intuition. These concepts were defined in terms of two psychometric tests used to measure personality and interest. The two tests used were the 19 Field Interest Inventory (19FII) and the Jung Personality Questionnaire (JPQ). Intuition was measured on a continuum in terms of Jung’s conceptualisation of intuition- sensation. Creative thought was conceived as both a cognitive and an unconscious process. The research was quantitative in nature. A comparison was done between the scores obtained on the personality questionnaire (JPQ) and the interest inventory (19FII) in order to determine if there was a link between intuition and creative thought. These results were inconclusive. Thereafter the study investigated whether the subjects enrolled for an engineering degree who used intuition as their dominant auxiliary function performed well in a course designed to promote creative thought. The results were inconclusive and this might be due to the small sample group and numerous variables that were not controlled.Dissertation (MA (Psychology))--University of Pretoria, 2006.
Psychology
unrestricted
32
Chen, Kuan-Ling, and 陳冠伶. "Meditation effect on amygdala reactivity to consciously and unconsciously emotional processing." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/m3wh64.
Full textAbstract:
碩士國立陽明大學
神經科學研究所
105
Meditation training is known to improve anxiety in relation with better attentional skills. The conscious and unconscious perception of threatening faces can elicit the amygdala reactivity, indicating state and trait anxiety, respectively. However, the effect of meditation on the amygdala reactivity in response to conscious and unconscious perception of emotional faces remains to be determined. Enrolling the meditators, who had continued to practice meditation for more than five years and the naïve controls, this study combined the assessment of the State-Trait Anxiety inventory (STAI), the detection task, and fMRI scanning for the color identification task in response to consciously and unconsciously perceived emotional faces. Results indicated that the mediator group performed longer reaction time for the color identification, than did the control group. The meditators had significantly lower scores on the STAI than naïve controls. The meditator group showed reduced amygdala reactivity regardless of conscious or non-conscious perception of emotional faces. The findings first provide direct evidence to support that meditation training could modulate amygdala reactivity, which, in turn, may have positive effect in anxiety.