The success of recent 3-D stereoscopic movies such as Avatar has created a lot of attention for 3-D in the home. Almost all major consumer electronics (CE) manufacturers have launched their 3-D stereoscopic displays in the market. A problem with those solutions is that viewers have to wear glasses. Glasses-free autostereoscopic 3-D displays typically use lenticular lenses or barriers to create multiple views. However these displays suffer from a number of issues: inverted views at viewing cone transitions, cross-talk between views, and need for multi-view content.  As Philips Electronics research group, we believe that some of these issues can be reduced by using pupil tracking. In the research process, we began with an extensive literature study on people detection and tracking techniques that helped us to understand the benefits and the shortcomings of different applications. Addition to literature studies, we greatly benefited from constant experimentation with prototypes and the hands-on experience with variety of digital and optical components under different conditions. As a result, we designed a multi-person infrared pupil tracker and multi-view renderer for 3D display to adapt the view rendering in real-time according to viewer’s position. Together with the integration of these two applications, the integrated 3D TV successfully adapts the center view according to position of the viewer and able to provide a smooth transition while the viewer actively changes her position from a notable distance under ambient illumination. However, even though the pupil tracker is implemented for multiple people, because of the time limitation and the complexity of the problem regarding multi-view renderer, the integrated system functions only for one person.   Exploring the employed technique, in-depth description and detailed illustration of designed applications and the conclusions drawn from the implemented system; we believe that this paper forms a substantial guidance and show-how source for further research in the field of 3D display and people tracking methods.

Über 90% der Informationsaufnahme beim Fahren erfolgt über den visuellen Sinneskanal. Das Auge ist das einzige fernorientierte Sinnesorgan, das über die Blickbewegungen gezielt ausrichtbar ist und die Erfassung räumlich voraus liegender Objekte ermöglicht. Somit spielt das Blickverhalten der Kraftfahrer eine zentrale Rolle beim Steuern eines Fahrzeugs. Da die Informationsaufnahme und -verarbeitung die Grundlage für Handlungsentscheidungen, ihre Realisierung und Kontrolle im Straßenverkehr bilden, bestimmt das Blickverhalten des Kraftfahrers weitestgehend sein Fahrverhalten und ist dadurch auch für die Verkehrssicherheit von zentraler Bedeutung. Mit Hilfe moderner Messtechnik lassen sich die Blickbewegungen genau registrieren und das Blickverhalten kann beim Autofahren exakt erfasst werden. Dadurch stellt die Analyse des Blickverhaltens ein neues Verfahren dar, mit dem der wahrnehmungspsychologische Faktor in der Wechselwirkung zwischen Fahrer, Fahrzeug und Straße berücksichtigt werden kann. Das Blickverhalten der Fahrer ist ein hochselektiver dynamischer Vorgang, durch den eine präzise Wahrnehmung von beweglichen bzw. unbeweglichen Objekten, Geschwindigkeiten und räumlichen Ausdehnungen gewährleistet ist. Die Analyse des Blickverhaltens ermöglicht sowohl den zeitlichen als auch den räumlichen Verlauf des detaillierten Informationszuflusses zusammen mit den Aufmerksamkeitsverlagerungen zu erforschen. Wo und in welchem Zeitpunkt der Fahrer detailliert hinblickt, kann mithilfe der Blickverhaltensanalyse ermittelt werden. In der Literatur sind verschiedene Blickverhaltensmaße vorhanden, mit denen das zeitliche Verhalten der visuellen Aufmerksamkeitsverteilung, die räumliche Konzentration des Blickes und die Intensität der Informationsaufnahme untersucht und interpretiert werden können. In der vorliegenden Arbeit werden aus dem breiten Spektrum dieser Maße diejenigen ausgewählt, die bezüglich der gesuchten Abhängigkeiten am aussagekräftigsten sind. Das Blickverhalten der Kraftfahrer wird in erheblichem Maße von der Streckenge-ometrie bestimmt. Aus der Forschung ist bekannt, dass die Verhältnisse beim Lenken eines Fahrzeugs entlang geraden Strecken und innerhalb von Kurven bezüglich der Beanspruchung des Fahrers und der Blickkonzentration nicht gleich sind. In Kurven ist die Belastung höher im Vergleich zu den Geraden und das führt zu einer gesteigerten Aufmerksamkeit. Das Blickverhalten in Links- und Rechtskurven charakterisiert sich mit bestimmten Blickmustern, die sich voneinander deutlich unterscheiden. Diesbezüglich werden entsprechende Untersuchungen und Analysen auch unter Einbeziehung der vorhandenen Sichtweite durchgeführt. Der Einfluss der streckencharakteristischen Parameter auf das Fahrverhalten und das Unfallgeschehen ist auf dem Gebiet des Straßenentwurfs seit langer Zeit Untersuchungsgegenstand zahlreicher Forschungsarbeiten. Auf Autobahnen sind jedoch nur wenige solche Untersuchungen vorhanden und ein Forschungsbedarf liegt auch diesbezüglich vor. In der Dissertation wurde die BAB A72 zwischen Hof und Chemnitz untersucht, die eine der ältesten Autobahnen Deutschlands ist und für die bekannt ist, dass sie Sicherheitsprobleme hat. Diese Bundesautobahn, die ursprünglich als Regionalautobahn sehr geländeangepasst trassiert worden ist, wurde im Zeitraum von 1990 bis 1995 grundhaft ausgebaut. Die Trasse ist unverändert geblieben und die Gradiente und der Querschnitt sind verbessert worden. Dadurch sind die Geschwindigkeiten deutlich gestiegen. So ein Ausbau kann zu Disproportionen in der räumlichen Linienführung führen. Auf der Autobahn A72 sind in einigen Abschnitten solche Disproportionen vorhanden. Ausdruck dafür ist das überdurchschnittlich hohe Unfallgeschehen. Die Verkehrssicherheit hat eine vorrangige Bedeutung für den Bau und den Betrieb jeder Straße. In der Arbeit wird durch das Blickverhalten von Fahrern mit einer neu entwickelten Methodik versucht, die Gründe für unsichere Abschnitte anders als mit den klassischen Methoden zu erforschen. Im Ergebnis werden Empfehlungen für einen Kurvenmindestradius und eine psychologische Mindestsichtweite untermauert.

資訊的進步讓學習者可透過多媒體進行動作學習，有偵測錯誤能力才能在無指導者的狀況下進行自我調整。本研究目的為探討多媒體教學影片講解順序對於學習者錯誤偵測能力的影響。研究對象為四年制大專學生，且無網球或其他持拍類運動背景60名 (男：33位；女：27位；年齡：22.0±1.0)。研究中預先設計A、B兩段網球正拍教學影片，A.先講解身體重心後講解球拍軌跡，以及B.先講解球拍軌跡後講解身體重心，實驗進行前參與者隨機觀看教學影片，建立認知基模，進行實驗時使用SMI 公司的RED遠距測量眼動儀，捕捉參與者偵測初學者網球正拍動作時的凝視軌跡，並以手機錄音的方式紀錄參與者口述偵測的錯誤，所得資料以獨立樣本t檢定處理分析 (α=.05)。結果顯示：1. 觀看不同順序的參與者凝視初學者正拍動作的視覺分配不同，其中手臂、軀幹的AOI達顯著差異；2. 分期階段的拉拍期手臂與軀幹的AOI達顯著差異；3. 擊球期與完成期則皆只有手臂AOI達顯著差異；4. 偵測錯誤結果上觀看A教學影片的參與者偵測較多錯誤，結果也達顯著差異。本研究結果發現不同順序教學影片對參與者偵測錯誤的視覺軌跡或能力皆有影響，建議未來網球正拍教學過程先給予身體重心的重點，將有利於學習者偵測錯誤能力提昇。 / The advent of information technology made learning motor skill through multimedia possible and error-detection ability is essential to self-regulate learning under no instructor condition. In order to study the effect of multimedia instructional video content sequence to the learner’s error-detection ability, this research used sixty (male:33; female:27; age: 22.0±1.0 yrs old) four-years university students with no tennis or racket sports experience as subjects. Two demonstration videos were designed: A: explain body Center of Gravity (CG) first follow by racket trajectory; B: explain racket trajectory first follow by body CG. Participants were randomly assigned to watch the videos to build-up their cognitive schema. The SMI RED remote eye tracker is used to capture participant’s gaze trajectory when watching the beginner’s Tennis forehand drive motion. A cellphone is used to record the participant’s dictation of detection of errors. Data gathered were analysed with independent t-test (α=.05). The results indicate that: 1. participants watching different video content sequence allocate their visual distribution differently, with the arm and truck AOI significantly different; 2. The AOI of arm and truck in backswing stage were significantly different; 3. In waving and follow through stage only the arm AOI exhibit significant difference. 4. In error-detection, watching the A instructional video group exhibit significant error-detection results. The results indicate instructional video content sequence affect the learner’s error-detection visual trajectory and ability. The author suggests that emphasize on body CG in tennis forehand drive instruction process can be favourable to the error-detection ability. / 第壹章 緒論 1 第一節 研究背景 1 第二節 研究目的 2 第三節 研究範圍與限制 2 第四節 操作性定義 3 第貳章 文獻探討 6 第一節 多媒體與學習理論 7 第二節 動作學習理論 14 第三節 眼動與運動相關研究 22 第四節 網球正拍動作 25 第五節 本章總結 27 第參章 研究方法 28 第一節 研究架構 28 第二節 研究對象 29 第三節 實驗時間與地點 29 第四節 教學影片與實驗素材 30 第五節 實驗儀器 32 第六節 場地布置 33 第七節 實驗步驟 34 第八節 收集資料與處理方法 40 第九節 統計分析方法 42 第十節 預備實驗 43 第肆章 結果與討論 45 第一節 凝視AOI區域分佈 46 第二節 偵測錯誤語音資料 51 第三節 偵測錯誤凝視順序 54 第四節 綜合討論 55 第伍章 結論與建議 58 第一節 結論 58 第二節 建議 58 參考文獻 60 附件一 正拍動作技術檢核表 67 附件二 人體研究倫理委員會通過證明 68 附件三 受試者同意書 69

Most South African subtitles are produced and broadcast in English despite the fact that English is the first language of only 8.2% of the entire population (Statistics South Africa, 2004). Therefore, current English subtitles are predominantly received as second language text. This poses questions as to how people perceive these subtitles, and if and how their reading of English second language (L2) subtitles differs from their reading of L1 (non-English) subtitles. In recent years, eye tracking has proven to be a valuable method in observing and measuring the eye movements of people watching and reading subtitles. In order to explain the use of eye tracking and in order to answer the question at hand, this study comprises a literature review and an empirical study. The literature review gives an in-depth account of previous studies that used eye tracking to study reading and elaborates on the parameters used to account for various findings. The two empirical components of this study examined the accessibility and effectiveness of English L2 subtitles by presenting native speakers of Afrikaans and Sesotho with subtitles displayed (a) in their native language, Afrikaans or Sesotho, and (b) in L2 English, while monitoring their eye movements with an SMI iViewX™ Hi-Speed eye tracker and comparing the data with that of English L1 speakers reading English subtitles. Participants were also given static text to read (accompanied by a corresponding comprehension test) in order to see if there was a relation between participants’ first and second language reading of static text and that of subtitling. Additionally, participants were given a questionnaire on their reading behaviour, reading preferences, access to subtitled television programming and reading of subtitles in order to find explanations for occurrences in the data. The initial hypothesis was that there would be a difference in L1 and L2 subtitle reading and attention allocation as measured by key eye-tracking parameters. Using ANOVAs, statistically significant differences were indeed found, but the differences were much more significant for the Sesotho L1 than the Afrikaans L1 speakers. After excluding possible confounding factors that were analysed in attempt to refute this hypothesis, the conclusion was that participants inherently read L1 and L2 subtitles differently. The hypothesis is therefore supported. However, the difference in L1 and L2 subtitle reading was not the only significant finding – the Sesotho L1 speakers’ reading data revealed a greater underlying issue, namely literacy. The problem of low literacy levels can be attributed to the participants’ socioeconomic background and history, and needs to be addressed urgently. Recommendations for future research include that the current study be broadened in terms of scope, sampling size, representativeness and experimental material; that the focus be shifted to the rest of the languages spoken in South Africa for which the users do not have a shared sense of bilingualism and for which the L1 skills and levels of L1 literacy vary; and to further explore the relation between the reading of static text and subtitle reading in order to ensure adequate subtitle reading in terms of proportional attention allocation. However, the issue of low literacy levels will have to be addressed urgently; only then will the South African viewing public be able to gain full access to any form of broadcast communicative material or media, and only then will they be able to benefit from subtitling and all that it offers. / North-West University (South Africa). Vaal Triangle Campus.

Most South African subtitles are produced and broadcast in English despite the fact that English is the first language of only 8.2% of the entire population (Statistics South Africa, 2004). Therefore, current English subtitles are predominantly received as second language text. This poses questions as to how people perceive these subtitles, and if and how their reading of English second language (L2) subtitles differs from their reading of L1 (non-English) subtitles. In recent years, eye tracking has proven to be a valuable method in observing and measuring the eye movements of people watching and reading subtitles. In order to explain the use of eye tracking and in order to answer the question at hand, this study comprises a literature review and an empirical study. The literature review gives an in-depth account of previous studies that used eye tracking to study reading and elaborates on the parameters used to account for various findings. The two empirical components of this study examined the accessibility and effectiveness of English L2 subtitles by presenting native speakers of Afrikaans and Sesotho with subtitles displayed (a) in their native language, Afrikaans or Sesotho, and (b) in L2 English, while monitoring their eye movements with an SMI iViewX™ Hi-Speed eye tracker and comparing the data with that of English L1 speakers reading English subtitles. Participants were also given static text to read (accompanied by a corresponding comprehension test) in order to see if there was a relation between participants’ first and second language reading of static text and that of subtitling. Additionally, participants were given a questionnaire on their reading behaviour, reading preferences, access to subtitled television programming and reading of subtitles in order to find explanations for occurrences in the data. The initial hypothesis was that there would be a difference in L1 and L2 subtitle reading and attention allocation as measured by key eye-tracking parameters. Using ANOVAs, statistically significant differences were indeed found, but the differences were much more significant for the Sesotho L1 than the Afrikaans L1 speakers. After excluding possible confounding factors that were analysed in attempt to refute this hypothesis, the conclusion was that participants inherently read L1 and L2 subtitles differently. The hypothesis is therefore supported. However, the difference in L1 and L2 subtitle reading was not the only significant finding – the Sesotho L1 speakers’ reading data revealed a greater underlying issue, namely literacy. The problem of low literacy levels can be attributed to the participants’ socioeconomic background and history, and needs to be addressed urgently. Recommendations for future research include that the current study be broadened in terms of scope, sampling size, representativeness and experimental material; that the focus be shifted to the rest of the languages spoken in South Africa for which the users do not have a shared sense of bilingualism and for which the L1 skills and levels of L1 literacy vary; and to further explore the relation between the reading of static text and subtitle reading in order to ensure adequate subtitle reading in terms of proportional attention allocation. However, the issue of low literacy levels will have to be addressed urgently; only then will the South African viewing public be able to gain full access to any form of broadcast communicative material or media, and only then will they be able to benefit from subtitling and all that it offers. / North-West University (South Africa). Vaal Triangle Campus.

Being able to generate predictions about what is going to happen next while observing other people’s actions plays a crucial role in our daily lives. Different theoretical explanations for the underlying processes of humans’ action prediction abilities have been suggested. Whereas an embodied account posits that predictive gaze relies on embodied simulations in the observer’s motor system, other accounts do not assume a causal role of the motor system for action prediction. The general aim of this thesis was to augment current knowledge about the functional mechanisms behind humans’ action prediction abilities. In particular, the present thesis outlines and tests an embodied account of action prediction. The second aim of this thesis was to extend prior action prediction studies by exploring infants’ online gaze during observation of social interactions. The thesis reports 3 eye-tracking studies that were designed to measure adults’ and infants’ predictive eye movements during observation of different manual and social actions. The first two studies used point-light displays of manual reaching actions as stimuli to isolate human motion information. Additionally, Study II used transcranial magnetic stimulation (TMS) to directly modify motor cortex activity. Study I showed that kinematic information from biological motion can be used to anticipate the goal of other people’s point-light actions and that the presence of biological motion is sufficient for anticipation to occur. Study II demonstrated that TMS-induced temporary lesions in the primary motor cortex selectively affected observers’ gaze latencies. Study III examined 12-month-olds’ online gaze during observation of a give-and-take interaction between two individuals. The third study showed that already at one year of age infants shift their gaze from a passing hand to a receiving hand faster when the receiving hand forms a give-me gesture compared to an inverted hand shape. The reported results from this thesis make two major contributions. First, Studies I and II provide evidence for an embodied account of action prediction by demonstrating a direct connection between anticipatory eye movements and motor cortex activity. These findings support the interpretation that predictive eye movements are driven by a recruitment of the observer’s own motor system. Second, Study III implicates that properties of social action goals influence infants’ online gaze during action observation. It further suggests that at one year of age infants begin to show sensitivity to social goals within the context of give-and-take interactions while observing from a third-party perspective.

Le but de cette thèse était la recherche de biomarqueurs des troubles de l'humeur (dépression unipolaire et troubles bipolaires). Compte tenu de l'étiologie de ces troubles (hypométabolisme du cortex préfrontal dorso-latéral et déficit de la neurotransmission GABA/glutamatergique), nous avons choisi d'étudier deux biomarqueurs : la performance saccadique et l'excitabilité corticale. Nos résultats montrent que les performances saccadiques (antisaccades) permettent (i) de discriminer les patients présentant des troubles de l'humeur de sujets sains, (ii) d'objectiver l'amélioration thymique des patients suite à un traitement, et (iii) d'évaluer l'effet neuromodulateur à court-terme d'une séance de stimulation magnétique transcrânienne répétée. Concernant les mesures d'excitabilité corticale, aucune différence liée à l'amélioration thymique des patients, ni de différences entre patients et contrôles ne ressortent significativement. Nous avons suggéré que le non-contrôle du « State-Dependency » (i.e., de l'« état neurocognitif » des sujets pendant les stimulations) puisse être l'une des causes de l'absence de résultats, et validé cette hypothèse en manipulant les registres cognitifs et émotionnels des sujets.Le second aspect de notre travail de thèse avait trait à l'étude de l'efficacité de la stimulation magnétique transcrânienne répétée (rTMS) comme alternative thérapeutique non médicamenteuse des troubles de l'humeur. Si la littérature s'accorde sur une efficacité significative mais modérée de la rTMS comme traitement, nos données n'ont pas mis en évidence de supériorité du traitement actif par rapport au traitement placebo dans le cas de la neurostimulation iTBS. Une des raisons de ce manque d'efficacité du traitement actif pourrait être liée à des questions d'ordre méthodologique, comme le choix des paramètres de stimulation. Plus généralement, cette absence de résultats incite à questionner le postulat théorique basant l'étude de la réactivité du CPFDL ou sa neuromodulation sur les propriétés du cortex moteur. Notre expérience, étudiant la réactivité de différentes zones corticales par couplage TMS-EEG, va dans ce sens en montrant que la réactivité du cortex moteur diffère de celle des autres cortex. Le couplage TMS-EEG devrait permettre de mieux comprendre l'impact de la neuromodulation rTMS sur la cible corticale visée, et donc d'adapter les paramètres de stimulations aux aires cérébrales stimulées, permettant à terme de traiter plus efficacement les troubles de l'humeur. / The aim of this doctoral thesis was to develop biomarkers for mood disorders (unipolar major depression and bipolar disorders). Considering mood disorders' etiology (Dorso lateral prefrontal cortex hypometabolism and GABA/glutamate neurotransmission deficits), we decided to study two biomarkers: saccadic performance and cortical excitability. Our results showed that saccadic performance (notably Antisaccades) allows (i) discriminating bipolar patients from healthy subjects, (ii) ascertaining patients' mood improvement, and (iii) evaluating the short-term neuromodulation induced by repetitive transcranial magnetic stimulation.Regarding cortical excitability measurements, our results did not reveal any differences neither between patients and healthy subjects, nor between Responders and non Responders to a treatment (Ketamine injection or rTMS). We suggested that the null results could be explained by the lack of control of State-Dependency. This assumption was tested and validated through the manipulation of the subjects' cognitive and emotional states.A second aim of this doctoral thesis was to study the efficacy of rTMS, a non pharmacological therapeutic alternative, as a treatment for mood disorders. Meta-analyses showed that anti depressant effect of rTMS seems to be significant but still moderate. In our experiment, mood improvement did not differ between active and sham rTMS. Basic methodological reasons such as stimulation parameters could explain this lack of efficacy. Overall, one could wonder about the validity of the theoretical postulate of rTMS, drawn upon motor cortex reactivity. This postulate inferred that both cortical reactivity of motor cortex and DLPFC are similar. Using TMS-EEG coupling, we studied the reactivity of these cortices, to TMS pulses, which revealed that motor cortex and DLPFC reactivities should not be assimilated. This result calls into question the relevance of the rTMS theoretical postulate. Coupling TMS and EEG should allow a better understanding of the impact of rTMS neuromodulatory effect over the targeted area, and thus to a better adaption of the stimulation parameters, which could lead to an improvement of rTMS efficacy as a treatment for mood disorders.

Nos travaux se sont articulés autour du problème de recouvrement temporel rencontré lors de l'estimation des potentiels évoqués. Il constitue, plus particulièrement, une limitation majeure pour l'estimation des potentiels évoqués par les fixations ou saccades oculaires lors d'une expérience en enregistrement conjoint EEG et oculométrie. En effet, la méthode habituellement utilisée pour estimer ces potentiels évoqués, la méthode par simple moyennage du signal synchronisé sur l'évènement d'intérêt, suppose qu'il y a un seul potentiel évoqué par essai. Or selon les intervalles inter-stimuli, cette hypothèse n'est pas toujours vérifiée. Ceci est d'autant plus vrai dans le contexte des potentiels évoqués par fixations ou saccades oculaires, les intervalles entre ceux-ci n'étant pas contrôlés par l'expérimentateur et pouvant être plus courts que les latences des potentiels d'intérêt. Le fait que cette hypothèse ne soit pas vérifiée donne une estimation biaisée du potentiel évoqué du fait des recouvrements entre les potentiels évoqués.Nous avons donc utilisé le Modèle Linéaire Général (GLM), méthode de régression linéaire bien connue, pour estimer les potentiels évoqués par les mouvements oculaires afin de répondre à ce problème de recouvrement. Tout d'abord, nous avons introduit, dans ce modèle, un terme de régularisation au sens de Tikhonov dans l'optique d'améliorer le rapport signal sur bruit de l'estimation pour un faible nombre d'essais. Nous avons ensuite comparé le GLM à l'algorithme ADJAR dans un contexte d'enregistrement conjoint EEG et oculométrie lors d'une tâche d'exploration visuelle de scènes naturelles. L'algorithme ADJAR ("ADJAcent Response") est un algorithme classique d'estimation itérative des recouvrements temporels développé en 1993 par M. Woldorff. Les résultats ont montré que le GLM était un modèle plus flexible et robuste que l'algorithme ADJAR pour l'estimation des potentiels évoqués par les fixations oculaires. Puis, deux configurations du GLM ont été comparées pour l'estimation du potentiel évoqué à l'apparition du stimulus et du potentiel évoqué par les fixations au début de l'exploration. Toutes deux prenaient en compte les recouvrements entre potentiels évoqués mais l'une distinguait également le potentiel évoqué par la première fixation de l'exploration du potentiel évoqué par les fixations suivantes. Il est apparu que le choix de la configuration du GLM était un compromis entre la qualité de l'estimation des potentiels et les hypothèses émises sur les processus cognitifs sous-jacents.Enfin, nous avons conduit de bout en bout une expérience d'envergure en enregistrement conjoint EEG et oculométrie portant sur l'exploration des expressions faciales émotionnelles naturelles statiques et dynamiques. Nous avons présenté les premiers résultats pour la modalité statique. Après avoir discuté de la méthode d'estimation des potentiels évoqués selon l'impact des mouvements oculaires sur leur fenêtre de latence, nous avons étudié l'effet du type d'émotion. Nous avons trouvé des modulations du potentiel différentiel EPN (Early Posterior Negativity), entre 230 et 350 ms après l'apparition du stimulus et du potentiel LPP (Late Positivity Potential), entre 400 et 600 ms après l'apparition du stimulus. Nous avons également observé des variations du potentiel évoqué par les fixations oculaires. Pour le potentiel LPP, qui est un marqueur de la reconnaissance consciente de l'émotion, nous avons montré qu'il était important de dissocier l'information qui est immédiatement encodée à l'apparition du stimulus émotionnel, de celle qui est apportée à l'issue de la première fixation. Cela met en évidence un motif d'activation différencié pour les stimuli émotionnels à valence négative ou à valence positive. Cette différenciation est en accord avec l'hypothèse d'un traitement plus rapide des stimuli émotionnels à valence négative que des stimuli émotionnels à valence positive. / Our research focuses on the issue of overlapping for evoked potential estimation. More specifically, this issue is a significant limitation for Eye-Fixation Related Potentials and Eye-Saccade Related Potentials estimations during a joint EEG and eye-tracking recording. Indeed, the usual estimation, by averaging the signal time-locked to the event of interest, is based on the assumption that a single evoked potential occurs during a trial. However, depending on the inter-stimulus intervals, this assumption is not always verified. This is especially the case in the context of Eye-Fixation Related Potentials and Eye-Saccade Related Potentials, given the fact that the intervals between fixations (or saccades) are not controlled by the experimenter and can be shorter than the latencies of the potentials of interest.The fact that this assumption is not verified gives a distorted estimate of the evoked potential due to overlaps between the evoked potentials.We have therefore used the Linear Model (GLM), a well-known linear regression method, to estimate the potentials evoked by ocular movements in order to take into account overlaps. First, we decided to introduce a term of Tikhonov regularization into this model in order to improve the signal-to-noise ratio of the estimate for a small number of trials. Then, we compared the GLM to the ADJAR algorithm in a context of joint EEG and eye-tracking recording during a task of visual exploration of natural scenes. The ADJAR ("ADJAcent Response") algorithm is an algorithm for iterative estimation of temporal overlaps developed in 1993 by M. Woldorff. The results showed that the GLM model was more flexible and robust than the ADJAR algorithm in estimating Eye-Fixation Related Potentials. Further, two GLM configurations were compared in their estimation of evoked potential at the onset of the stimulus and the eye-fixation related potential at the beginning of the testing. Both configurations took into account the overlaps between evoked potentials, but one additionally distinguished the potential evoked by the first fixation of the exploration from the potential evoked by the following fixations. It became clear that the choice of the GLM configuration was a compromise between the estimation quality of the potentials and the assumptions about the underlying cognitive processes.Finally, we conducted an extensive joint EEG and eye-tracking experiment on the exploration of static and dynamic natural emotional facial expressions. We presented the first results for the static modality. After discussing the estimation method of the evoked potentials according to the impact of the ocular movements on their latency window, we studied the influence of the type of emotion. We found modulations of the differential EPN (Early Posterior Negativity) potential, between 230 and 350 ms after the stimulus onset and the Late Positivity Potential (LPP) , between 400 and 600 ms after the stimulus onset. We also observed variations for the Eye-Fixation Related Potentials. Regarding the LPP component, a marker of conscious recognition of emotion, we have shown that it is important to dissociate information that is immediately encoded at the onset of the emotional stimulus from information encoded at the first fixations. This shows a differentiated pattern of activation according to the emotional stimulus valence. This differentiation is in agreement with the hypothesis of a faster treatment of negative emotional stimuli than of positive emotional stimuli.

For elderly Canadians, the prevalence of vision impairment caused by degenerative retinal pathologies, such as age-related macular degeneration and retinitis pigmentosa, is at an occurrence rate of 14 percent, and on the rise. It has been shown that visual function can be restored by electrically stimulating intact retinal tissue with an array of micro-electrodes with suitable signals. Commercial retinal implants carrying such a micro-electrode array achieve this, but to date must receive power and data over copper wire cable passing through a permanent surgical incision in the eye wall (sclera). This project is defined by a collaboration with iBIONICS, who are developing retinal implants for treatment of such conditions. iBIONICS has developed the Diamond Eye retinal implant, along with several technology sub-systems to form a comprehensive and viable medical solution. Notably, the Diamond Eye system can be powered wirelessly, with no need for a permanent surgical incision. The thesis work is focused on the formulation, simulation and hardware demonstration of a powering system, mounted on glasses frame, for a retinal implant. The system includes a Micro-Electro-Mechanical System (MEMS) mirror that directs a laser beam to the implant through the pupil opening. The work presented here is built on two main components: an iterative predictor-corrector algorithm (Kalman filter) that estimates pupil coordinates from measurements provided by an image-based eye tracking algorithm; and an misalignment compensation algorithm that maps eye pupil coordinates into mirror coordinates, and compensates for misalignment caused by rigid body motions of the glasses lens mirror and the MEMS mirror with respect to the eye. Pupil tracker and misalignment compensation control performance are illustrated through simulated scenarios. The project also involves the development of a hardware prototype that is used to test algorithms and related software.

abstract: Medical images constitute a special class of images that are captured to allow diagnosis of disease, and their "correct" interpretation is vitally important. Because they are not "natural" images, radiologists must be trained to visually interpret them. This training process includes implicit perceptual learning that is gradually acquired over an extended period of exposure to medical images. This dissertation proposes novel computational methods for evaluating and facilitating perceptual training in radiologists. Part 1 of this dissertation proposes an eye-tracking-based metric for measuring the training progress of individual radiologists. Six metrics were identified as potentially useful: time to complete task, fixation count, fixation duration, consciously viewed regions, subconsciously viewed regions, and saccadic length. Part 2 of this dissertation proposes an eye-tracking-based entropy metric for tracking the rise and fall in the interest level of radiologists, as they scan chest radiographs. The results showed that entropy was significantly lower when radiologists were fixating on abnormal regions. Part 3 of this dissertation develops a method that allows extraction of Gabor-based feature vectors from corresponding anatomical regions of "normal" chest radiographs, despite anatomical variations across populations. These feature vectors are then used to develop and compare transductive and inductive computational methods for generating overlay maps that show atypical regions within test radiographs. The results show that the transductive methods produced much better maps than the inductive methods for 20 ground-truthed test radiographs. Part 4 of this dissertation uses an Extended Fuzzy C-Means (EFCM) based instance selection method to reduce the computational cost of transductive methods. The results showed that EFCM substantially reduced the computational cost without a substantial drop in performance. The dissertation then proposes a novel Variance Based Instance Selection (VBIS) method that also reduces the computational cost, but allows for incremental incorporation of new informative radiographs, as they are encountered. Part 5 of this dissertation develops and demonstrates a novel semi-transductive framework that combines the superior performance of transductive methods with the reduced computational cost of inductive methods. The results showed that the semi-transductive approach provided both an effective and efficient framework for detection of atypical regions in chest radiographs. / Dissertation/Thesis / Ph.D. Computer Science 2012