The remarkable ability of the human brain to draw an accurate percept from imprecise sensory information is not well understood. Bayesian inference provides an optimal means for drawing perceptual conclusions from sensorineural activity. This approach has frequently been applied to visual and auditory studies but only rarely to studies of tactile perception. We explored whether a Bayesian observer model could replicate fundamental aspects of human tactile spatial perception. The model consisted of an encoder that simulated sensorineural responses with Poisson statistics followed by a decoder that interpreted the observed firing rates. We compared the performance of our Bayesian observer on a battery of tactile tasks to human participant data collected previously by our laboratory and others. The Bayesian observer replicated human performance trends on three spatial acuity tasks: classic two-point discrimination (C2PD), sequential two-point discrimination (S2PD), and two-point orientation discrimination (2POD). We confirmed the widely reported observation that C2PD is the least reliable method of assessing tactile acuity due presumably to the presence of non-spatial cues. Additionally, the Bayesian observer performed similarly to humans on raised letter and Braille character-recognition tasks. The Bayesian observer further replicated two illusions previously reported in humans: an adaptation-induced repulsion illusion and an orientation anisotropy illusion. Taken together, these results suggest that human tactile spatial perception may arise from a Bayesian-like decoder that is unaware of the precise characteristics of its inputs. / Thesis / Master of Science (MSc)

Page 193 is included twice. Numbered the same, but are different pages. / Although visual illusions have been used extensively to explore the mechanisms subserving perception and action, controversy exists regarding the extent to which illusions may differentially affect the perceptual and motor systems. In part, this is because it is often difficult to accurately assess the perceptual influence of illusory stimuli since participants are usually asked only to report binary size decisions (bigger or smaller) of an illusory stimulus relative to a control figure. Questions of relative size or the direction of misperception remain unanswered. In this thesis, 10 experiments, comprising eight separate studies, were conducted to address these issues. In Experiment 1, a software tool was developed that allowed participants to size-match a target to a Control figure (Experiment 1a), as well as both the Large (Experiment 1b) and Small Annuli (Experiment 1c) Ebbinghaus Illusion stimuli. These experiments provided an accurate percentage of misperception score when each of the three conditions was presented in isolation. Results from Experiment 2, however, suggest that when each of the three conditions are presented in a random and repeated stimulus array, a degree of perceptual adaptation occurs in which illusory effects are biased in the direction of the large annuli stimulus. Experiments 3-8 provided evidence to suggest that the degree of motor involvement (Experiment 3), number of illusory stimuli present (Experiments 4 and 5), direction of attention (Experiment 6) and visual field laterality (Experiments 7 and 8) have minimal influence on the adaptation effects observed in Experiment 2. / Thesis / Master of Science (MSc)

Dans le but de mieux comprendre le rôle et le fonctionnement des régions cérébrales impliquées dans le traitement et la modulation de la perception douloureuse, la première partie de cette thèse s’intéresse à l’évaluation en IRMf des modifications de la réponse cérébrale à la douleur grâce à deux modulations de la perception douloureuse. La première s’intéresse à l’effet d’un contexte émotionnel négatif sur la perception douloureuse afin de dissocier des aires cérébrales répondant à la douleur, les réponses liées à la composante émotionnelle. La deuxième s’intéresse à l’effet d’une manipulation de l’appréciation de la durée d’une stimulation douloureuse sur la perception de la douleur. L’utilisation d’une illusion permet, pour une intensité de stimulation thermique donnée, de modifier la perception douloureuse et d’évaluer les zones cérébrales impliquées dans ce type de modulation. Nous avons modulé la douleur perçue et pu observer que l’émotion met en jeu la partie prégénuale du cortex cingulaire antérieur, tandis que l’illusion d’une durée raccourcie met en jeu un réseau occipito-pariétal attentionnel. La seconde partie de cette thèse s’intéresse à la caractérisation du décours temporel de la réponse hémodynamique dans deux régions importantes pour le traitement de l’information douloureuse qui sont l’insula et le cortex cingulaire. La douleur est caractérisée par une latence de la réponse plus courte, par rapport à une stimulation non-douloureuse, dans l’insula antérieure et le cortex cingulaire moyen, tandis qu’il est possible de différencier une stimulation douloureuse d’une stimulation non-douloureuse grâce à l’amplitude de la réponse dans l’insula postérieure. / Pain is a complex and multidimensional experience that can be modulated by many factors. In order to better understand the respective role and function of the brain regions involved in the processing and the modulation of pain perception, the first part of this thesis focuses on the evaluation with functional magnetic resonance imaging (fMRI) of changes in the brain response to pain through two modulations of pain perception. The first study examines the effect of a negative emotional context on pain perception in order to dissociate the brain areas responding to pain from that related to the emotional context. The second study focuses on the effect of the manipulation of perceived duration of a painful stimulation on the perception of pain. The use of this illusion allows us to change the perceived intensity of pain and to assess the brain areas involved in this type of modulation at given intensity of thermal stimulation. We succeeded to increase or decrease perceived pain intensity and we observed that emotion involves pregenual part of the anterior cingulate cortex, while the illusion of a shortened duration involves an occipito-parietal attentional network. The second part of this thesis focuses on characterizing the time course of the hemodynamic response recorded with fMRI in two important areas processing pain that are the insula and the cingulate cortex. Painful sensation is characterized by a shortened latency of hemodynamic response compared to a non-painful sensation in the anterior insula and the midcingulate cortex, while it is possible to differentiate painful and non-painful sensation by the amplitude of the hemodynamic response in the posterior insula.

Cette thèse traite de modèles mésoscopiques de cortex appelés champs neuronaux. Les équations des champs neuronaux décrivent l'activité corticale de populations de neurones, ayant des propriétés anatomiques/fonctionnelles communes. Elles ont été introduites dans les années 1950 et portent le nom d'équations de Wilson et Cowan. Mathématiquement, elles consistent en des équations intégro-différentielles avec retards, les retards modélisant les délais de propagation des signaux ainsi que le passage des signaux à travers les synapses et l'arbre dendritique. Dans la première partie, nous rappelons la biologie nécessaire à la compréhension de cette thèse et dérivons les équations principales. Puis, nous étudions ces équations du point de vue des systèmes dynamiques en caractérisant leurs points d'équilibres et la dynamique dans la seconde partie. Dans la troisième partie, nous étudions de façon générale ces équations à retards en donnant des formules pour les diagrammes de bifurcation, en prouvant un théorème de la variété centrale et en calculant les principales formes normales. Nous appliquons tout d'abord ces résultats à des champs neuronaux simples mono-dimensionnels qui permettent une étude détaillée de la dynamique. Enfin, dans la dernière partie, nous appliquons ces différents résultats à trois modèles de cortex visuel. Les deux premiers modèles sont issus de la littérature et décrivent respectivement une hypercolonne, /i.e./ l'élément de base de la première aire visuelle (V1) et un réseau de telles hypercolonnes. Le dernier modèle est un nouveau modèle de V1 qui généralise les deux modèles précédents tout en permettant une étude poussée des effets spécifiques des retards / This thesis deals with mesoscopic models of cortex called neural fields. The neural field equations describe the activity of neuronal populations, with common anatomical / functional properties. They were introduced in the 1950s and are called the equations of Wilson and Cowan. Mathematically, they consist of integro-differential equations with delays, the delays modeling the signal propagation and the passage of signals across synapses and the dendritic tree. In the first part, we recall the biology necessary to understand this thesis and derive the main equations. Then, we study these equations with the theory of dynamical systems by characterizing their equilibrium points and dynamics in the second part. In the third part, we study these delayed equations in general by giving formulas for the bifurcation diagrams, by proving a center manifold theorem, and by calculating the principal normal forms. We apply these results to one-dimensional neural fields which allows a detailed study of the dynamics. Finally, in the last part, we study three models of visual cortex. The first two models are from the literature and describe respectively a hypercolumn, i.e. the basic element of the first visual area (V1) and a network of such hypercolumns. The latest model is a new model of V1 which generalizes the two previous models while allowing a detailed study of specific effects of delays

Dans notre vie quotidienne, nous recueillons et intégrons constamment un grand nombre d’informations sensorielles (Calvert & Thesen, 2004). Tout au long de nos activités perceptives, les connaissances que nous avons sur l’environnement sont continuellement "récupérées" en mémoire. Le cadre de la cognition incarnée et située proposent que les processus cognitifs (i.e. processus mnésiques, processus langagiers) sont ancrés dans les mêmes systèmes sensorimoteurs que ceux engagés dans les processus perceptivo-moteurs (Glenberg, 1997 ; Slotnick, 2004 ; Pecher & Zwaan, 2005).La mémoire contient des traces sensori-motrices encodées lors des multiples expériences de l’individu dans son environnement (Versace, Labeye, Badard, & Rose, 2009). De nombreux travaux en psychologie cognitive et en neurosciences démontrent que les connaissances sont construites et (re)émergent à partir de l’activation des systèmes neuronaux typiquement associés aux mécanismes perceptivo-moteurs. Le contenu et le fonctionnement de notre mémoire sont intrinsèquement liés à nos activités sensori-motrices passées et présentes. Pour être efficace, les connaissances impliquées dans nos activités cognitives doivent être étroitement liées à la situation présente. Cette capacité à s’adapter à des situations spécifiques ne serait pas possible à moins que les connaissances, y compris les connaissances conceptuelles, soientissues de la réactivation de traces mnésiques d’expériences passées (Barsalou, 2008 ; Versace et al., 2014). Réciproquement, les activités sensori-motrices sont totalement dépendantes des traces mnésiques d’expériences sensori-motrices passées. Ainsi, la différence entre perception et mémoire réside dans le fait que, dans le premier cas, les propriétés sont perceptivement présentes, tandis que, dans le deuxième cas, celles-ci sont absentes mais réactivées.Ce travail de thèse avait pour objectif d’étudier les liens entre mémoire et perception et, plus précisément, d’apporter des arguments en faveur de la similarité entre les processus mnésiques et perceptifs qui résultent de l’activation de composants de même nature sensorimotrice.Nous avons testé l’hypothèse selon laquelle des effets perceptifs devraient pouvoir être obtenus avec des composants réactivés en mémoire. Pour cela, nous avons utilisé des effets perceptifs - tels que l’effet de masquage ou les biais de jugement perceptif - afin d’explorer la possibilité de répliquer ce type d’effets avec l’intervention des dimensions mnésiques. / In everyday life, each of us is constantly processing perceptual input from the environment, we collect and then integrate numerous items of sensory information (Calvert & Thesen, 2004). Alongside these perceptual activities, knowledge related to our environment is continually "recovered" from memory. Embodied cognition and grounded cognition theories suggest that cognitive processes (e.g., memory processes, language processes) are grounded in the same sensory-motor systems as those used in perceptual and motor processes (Glenberg, 1997 ; Slotnick, 2004 ; Pecher & Zwaan, 2005).Memory is composed of sensorimotor traces encoded during the several experiences of an individual in his environment (Versace et al., 2009). A large number of studies in cognitive psychology and neurosciences demonstrated that knowledge is constructed and (re)emerged from the activation of neural systems typically associated with perceptual-motor mechanisms. The contents and the functioning of our memory are intrinsically linked to our past and present sensorimotor activities. To be effective, knowledge involved in our cognitive activities must be closely linked to the actual situation. This ability to adapt to specific situations would not be possible unless knowledge, including conceptual knowledge, is derived from the reactivation of memory traces of past experiences (Barsalou, 2008 ; Versace et al., 2014). Conversely, sensorimotor activities are totally dependent on memory traces of past sensorimotor experiences. Thus, the difference between perception and memory is that, in the former, properties are perceptually present, whereas, in the latter, they are absent but reactivated. This PhD research focused on the link between memory and perception and, more precisely, aims to provide arguments in favor of the similarity of memory and perceptual processes that result from the activation of components of same sensorimotor nature. We tested the hypothesis that perceptual effects should be observed with reactivated components in memory. We used well-known perceptual effects (such as masking effect or perceptual bias invisual illusion) to investigate the possibility to replicate these effects by replacing the sensorial present components by reactivated components in memory.

A pesquisa traz uma crítica à teoria moderna de finanças em relação à política de gestão de risco, especificamente sobre o Value at Risk, e como ela afeta o risco na economia. O trabalho propõe uma discussão comportamental da ineficácia do VaR e como este tipo de informação pode ser ruim para a economia, por refletir no problema do moral hazard (risco moral) para os gestores, baseados na ilusão de compreensão, ilusão de validade e de habilidade. A dissertação conclui que,ao superestimar a informação do VaR, os agentes alteram seu comportamento para tomar decisão e, com este risco moral, podem gerar o problema dos black swans (cisnes negros). / The research brings a critique of modern finance theory in relation to risk management policy, specifically on the Value at Risk, and how this affects the risk in the economy. The paper proposes a behavioral discussion of VaR ineffectiveness and how such information may be bad in the economy, for reflecting on the moral hazard problem for managers, based on the illusion of understanding, illusion of validity and ability. The dissertation concludes that, to overestimate VaR information, the agents change their behavior to take this decision and, this moral hazard, can generate the black swans.

<p><em><p>“Money is controlled by a market; I trust the government has control. I do not think you are right, of course the government has the control and they would not do like this, it cannot be true that my savings is not real, I work hard for them! But just stop it I just do not want to make these kinds of questions to myself; I just need a house, go traveling and have some fun, I do not want to go around and worrying”.(Anonym comment)</p><p>This comment by a person with university degree in business and middle manager at one of the larger Swedish companies, when discussing the thesis you are about to read, without the person having reading it in advance, actually seems representative for the overall knowledge about what is really going on in the financial system today and the willingness of people question it. The knowledge you will obtain and the result you will experience after finished your reading is challenges of basic “taken for granted assumptions” of businessmen, academics or people in general within the society today, for the purpose of understanding the system and its role in society. You will experience a unique critical presentation of the financial system today, and also discover that this knowledge about the financial system is not a knowledge the majority should possess, even one of the important principles of the system might be just that the majority do not possess this knowledge.</p><p>The financial system, when the time of writing, suffer from large global problems. This thesis is examining the foundation of the system, such as the concept of money, and the forces and principles within the system. The research goes from how the system has developed historically to how it is constructed and maneuvered today. Money is described as trading tools which value is only an illusion of value for persons in the society. The financial system is further broken down into three different subsystems in order to understand the term financial system. From the perspective of the three subsystems the financial system is described as a deceiving system fooling the participants that they possess value in forms of bank notes and coins. Further the thesis shifts the focus to how the system looks today by categorizing actors and tools in the system, how state authorities is trying to maneuver the system and create a network model of the Swedish financial system, the conclusion became that no one can escape the system and do not have a chance not to enter the system, the chapter also reveals how no one really has the power to control and influence the system. Finally the thesis provides foundations for the reader to make his own opinion if the gambling within the system has been taken to long, if the financial system could be labeled as a pyramid scheme, if the system has provided more benefits than drawbacks to society and finally some speculation in consequences if the system would crash and speculation of how historians in the future would describe the present version of the financial system. But before starting reading, think about the message from the director Alan Alda:</p><em><p>“Your assumptions are your windows on the world. Scrub them off every once in a while, or the light won’t come in”</p><p>(Citation: Alan Alda, Quoteland, n.d)</p></em></em></p>

“Money is controlled by a market; I trust the government has control. I do not think you are right, of course the government has the control and they would not do like this, it cannot be true that my savings is not real, I work hard for them! But just stop it I just do not want to make these kinds of questions to myself; I just need a house, go traveling and have some fun, I do not want to go around and worrying”.(Anonym comment) This comment by a person with university degree in business and middle manager at one of the larger Swedish companies, when discussing the thesis you are about to read, without the person having reading it in advance, actually seems representative for the overall knowledge about what is really going on in the financial system today and the willingness of people question it. The knowledge you will obtain and the result you will experience after finished your reading is challenges of basic “taken for granted assumptions” of businessmen, academics or people in general within the society today, for the purpose of understanding the system and its role in society. You will experience a unique critical presentation of the financial system today, and also discover that this knowledge about the financial system is not a knowledge the majority should possess, even one of the important principles of the system might be just that the majority do not possess this knowledge. The financial system, when the time of writing, suffer from large global problems. This thesis is examining the foundation of the system, such as the concept of money, and the forces and principles within the system. The research goes from how the system has developed historically to how it is constructed and maneuvered today. Money is described as trading tools which value is only an illusion of value for persons in the society. The financial system is further broken down into three different subsystems in order to understand the term financial system. From the perspective of the three subsystems the financial system is described as a deceiving system fooling the participants that they possess value in forms of bank notes and coins. Further the thesis shifts the focus to how the system looks today by categorizing actors and tools in the system, how state authorities is trying to maneuver the system and create a network model of the Swedish financial system, the conclusion became that no one can escape the system and do not have a chance not to enter the system, the chapter also reveals how no one really has the power to control and influence the system. Finally the thesis provides foundations for the reader to make his own opinion if the gambling within the system has been taken to long, if the financial system could be labeled as a pyramid scheme, if the system has provided more benefits than drawbacks to society and finally some speculation in consequences if the system would crash and speculation of how historians in the future would describe the present version of the financial system. But before starting reading, think about the message from the director Alan Alda: “Your assumptions are your windows on the world. Scrub them off every once in a while, or the light won’t come in” (Citation: Alan Alda, Quoteland, n.d)

A pesquisa traz uma crítica à teoria moderna de finanças em relação à política de gestão de risco, especificamente sobre o Value at Risk, e como ela afeta o risco na economia. O trabalho propõe uma discussão comportamental da ineficácia do VaR e como este tipo de informação pode ser ruim para a economia, por refletir no problema do moral hazard (risco moral) para os gestores, baseados na ilusão de compreensão, ilusão de validade e de habilidade. A dissertação conclui que,ao superestimar a informação do VaR, os agentes alteram seu comportamento para tomar decisão e, com este risco moral, podem gerar o problema dos black swans (cisnes negros). / The research brings a critique of modern finance theory in relation to risk management policy, specifically on the Value at Risk, and how this affects the risk in the economy. The paper proposes a behavioral discussion of VaR ineffectiveness and how such information may be bad in the economy, for reflecting on the moral hazard problem for managers, based on the illusion of understanding, illusion of validity and ability. The dissertation concludes that, to overestimate VaR information, the agents change their behavior to take this decision and, this moral hazard, can generate the black swans.

L’enjeu de cette thèse sur Henry Fuseli est de tenter de montrer la façon dont cet artiste a conçu sa pratique de la peinture d’histoire comme un véritable spectacle. En nous appuyant notamment sur l’analyse du corpus d’œuvres shakespeariennes peintes, dessinées et gravées par l’artiste entre 1768 et 1825, nous avons essayé de mettre au jour les processus de « spectacularisation » à l’œuvre chez Fuseli. L’étude de la participation de l’artiste à la société anglaise et à ses divertissements - spectacles privés, fréquentation des théâtres publics et d’attractions plus populaires - a permis de mesurer en quoi une culture visuelle bien plus large que celle issue de la simple production théâtrale informe la production de l’artiste. Le spectacle populaire, véritable modèle caché du peintre, a nourri la réflexion de Fuseli sur la recherche de l’effet en peinture, dans sa relation avec la mémoire du spectateur. Contre l’idée commune faisant de Fuseli un peintre visionnaire, ancrant son œuvre dans sa seule imagination, cette thèse a pour ambition de montrer la nature du rapport éminemment matériel que l’artiste entretint avec les spectacles de son temps. La mise au jour du rôle des réminiscences de la scène de théâtre dans la création picturale et l’étude du transfert d’un certains nombre de « signes matériels » de la scène au tableau (tels que le cadre, les portes, le rideau…), nous ont permis de mettre en évidence l’esthétique en acte dans la peinture d’histoire de Fuseli. C’est la question de la relation que cette peinture instaure avec son spectateur qui clôt notre étude : une forme de pacte au sein duquel celui qui peint et celui qui regarde s’accordent, le temps du regard, pour croire à ce qui est donné à voir, afin d’en éprouver l’effet. / Trying to demonstrate how Henry Fuseli’s practice of history painting was truly conceived as a show is what is the challenge of this thesis. By basing ourselves mainly on the analysis of the corpus of Shakespearian paintings, drawings and engravings made by the artist between 1768 and 1825, we have tried to highlight the processes of spectacularisation (theatrical devices) within Fuseli’s work. The study of the artist’s involvement in the english society – his attendance to various entertainments such as privates shows, public theatres or even more popular scenes – enabled us to measure that the artist’s production is the result not only of the mere theater scene but accounts for a much broader visual culture. Hidden model for the painter, the popular scene nourished Fuseli’s thoughts in the search for painting effects and the induced relationship with the spectator’s memory. Despite the common belief of Fuseli being a visionary painter who’s work sets roots solely in his imagination, this thesis ambition is to show the very concrete and material links of the artist with the scenes of his time. Highlighting reminiscences of the theatre scene in the pictorial creation and the moving from the scene to the painting of a number of “material signs” (such as the frame, the doors, the curtain…) have enabled us to show the aesthetics performing within Fuseli’ history paintings. Our study ends with the relationship that these paintings generate with their spectator : a kind of pact in which for the time of a glance painter and spectator agree to believe in what is given to see so as to experi-ence its effects.