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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

The Reading of Formulaic Sequences in a Native and Non-Native Language: An Eye Movement Analysis

Gerard, Jessica Eve January 2007 (has links)
This study contributes to the growing body of formulaic language research that indicates that formulaic sequences (e.g., idioms, collocations, metaphors, and other conventionalized multi-word items) facilitate comprehension by reducing processing load (Wray, 2002). Expanding on Underwood et. al. (2004), this study combines corpus analysis and eye-movement data to assess the contribution of formulaicity to the comprehension of a whole, authentic text.Information regarding grammatical, lexical, and contextual conventions for each formulaic item in the text was obtained via the Collins COBUILD Online Corpus and the British National Corpus. Additionally, using an Applied Science Laboratories Eye Tracker, the eye movements of two native speakers and one non-native speaker of English were recorded and the fixations for formulaic sequences were compared. All eye movement data was interpreted in light of Goodman's Transactional model of reading (2003). Specifically, eye movements for each participant were compared across two conditions: 1) a condition comprised of the formulaic sequences in the text and 2) a baseline segment from the text which was free of formulaic items. Paired t-tests were performed for each participant to determine whether or not the eye movement behavior differed significantly in the two conditions. Data analysis indicates that both native and non-native readers of English showed significant differences in the eye movement patterns for the two conditions. However, these significant differences were reversed for the two participant groups. In the case of the native readers, the predictable nature of formulaic sequences facilitated the processing of written text, as evidenced by a significantly lower percentage of words fixated in the formulaic sequences in comparison with the percent of words fixated in the baseline condition. However, for the non-native readers, 1) lack of experience with the formulaic items and 2) their opaque nature appeared to hinder comprehension, resulting in a significantly higher percentage of words fixated in the formulaic condition than in the baseline, non-formulaic condition. This dissertation has implications for the fields of first and second language acquisition, particularly literacy theory and instruction.
52

Le contrôle cognitif des mouvements oculaires : influence du vieillissement, de la maladie d'Alzheimer et de la dépression / The cognitive control of eye movements : influence of ageing, Alzheimer's disease and depression

Noiret, Nicolas 11 December 2017 (has links)
Le présent travail de thèse par articles visait à apporter sa contribution, d’une part à la compréhension des relations entre mouvements oculaires et vieillissement cognitif normal et pathologique, d’autre part à la caractérisation des modifications oculomotrices spécifiques à la maladie d’Alzheimer et à la dépression, deux pathologies parfois cliniquement difficiles à discriminer chez la personne âgée. À travers une série de quatre articles et une expérience non publiée, nous avons examiné les relations entre le déclin des capacités de contrôle cognitif associé au vieillissement normal et les modifications des paramètres des saccades oculaires liées à l’âge. Par ailleurs, nous avons également étudié précisément les caractéristiques de différents paramètres des saccades et leurs liens avec l’altération du contrôle cognitif dans la maladie d’Alzheimer. La comparaison directe des performances oculomotrices de patients atteints de la maladie d’Alzheimer et de patients âgés atteints de dépression a permis de différencier des caractéristiques oculomotrices spécifiques à la maladie d’Alzheimer de celles spécifiques à la dépression du sujet âgé. Enfin, nous avons pu mettre en évidence la spécificité de l’analyse visuelle des informations émotionnelles des visages chez des patients âgés souffrant de dépression.Dans l’ensemble, ces travaux ont montré une influence du déclin cognitif lié à l’âge, mais aussi de la dépression et de la maladie d’Alzheimer sur les performances oculomotrices. Le ralentissement du traitement de l’information semble avoir un impact sur les paramètres des saccades sur toutes les tâches proposées. La latence et le nombre de saccades erronées ont pu être associés aux capacités d’inhibition. Le nombre et le temps de correction des saccades corrigées étaient plutôt liés aux capacités de surveillance (monitoring) et de flexibilité cognitive. Les capacités de correction des saccades erronées dans la dépression étaient similaires à celles du vieillissement normal, mais altérées dans la maladie d’Alzheimer. La latence des saccades était par contre plus influencée par la dépression que par la maladie d’Alzheimer. De plus, le traitement des stimuli émotionnels a révélé des stratégies particulières chez les patients âgés atteints de dépression – un évitement des caractéristiques émotionnelles des visages, excepté pour la joie – qui pourraient être différentes de l’altération de la recherche visuelle retrouvée dans la maladie d’Alzheimer par des études antérieures. Que ce soit au travers des tâches de saccades ou d’exploration visuelle, les mouvements oculaires peuvent refléter les processus de contrôle cognitif et permettre de différencier la dépression de maladie d’Alzheimer. / This doctoral dissertation aimed at better characterizing the relations between eye movements and normal and pathological cognitive ageing on the one hand, and the oculomotor modifications related to Alzheimer's disease and depression – two pathologies sometimes clinically difficult to discriminate in the elderly person — on the other hand. Through a series of five experiments, we examined the relations between the decline of the cognitive control capacities associated with normal ageing and the age-related modifications of the ocular saccade parameters. In addition, we also precisely studied the characteristics of various saccade parameters and their relations with the deterioration of cognitive control, present in the Alzheimer's disease. The direct comparison of the oculomotor performances of patients suffering from the Alzheimer's disease and elderly patients suffering from depression allowed us to differentiate the oculomotor characteristics specific to the Alzheimer's disease from those specific to the depression. Lastly, we highlighted the specificity of the visual process of emotional faces among elderly patients suffering from depression.Globally, this work showed an influence of the cognitive decline related to the age, but also of the depression and Alzheimer's disease on the oculomotor performances. The information processing slowing seems to have an impact on the parameters of all the saccadic tasks. The latency and the number of erroneous saccades were associated with the inhibition capacities. The number and the time of correction of corrected saccades were rather related to the monitoring and flexibility abilities. The capacities of correction of erroneous saccades in depression were similar to those of normal ageing, but impaired in Alzheimer's disease. On the other hand, the saccade latency appears to be more impacted by depression than by Alzheimer's disease. Moreover, the emotional face processing revealed the presence of particular strategies among elderly patients suffering from depression – avoidance of the emotional facial features, except for happy faces – and which could be different from the alteration of the visual search previously found in Alzheimer's disease. Whether it be in saccade tasks or in visual exploration tasks, eye movements can reflect cognitive control and enable us to differentiate depression from Alzheimer’s disease.
53

Detecting distraction and degraded driver performance with visual behavior metrics

Yekhshatyan, Lora 01 December 2010 (has links)
Driver distraction contributes to approximately 43% of motor-vehicle crashes and 27% of near-crashes. Rapidly developing in-vehicle technology and electronic devices place additional demands on drivers, which might lead to distraction and diminished capacity to perform driving tasks. This situation threatens safe driving. Technology that can detect and mitigate distraction by alerting drivers could play a central role in maintaining safety. Correctly identifying driver distraction in real time is a critical challenge in developing distraction mitigation systems, and this function has not been well developed. Moreover, the greatest benefit may be from real-time distraction detection in advance of dangerous breakdowns in driver performance. Based on driver performance, two types of distraction - visual and cognitive - are identified. These types of distraction have very different effects on visual behavior and driving performance; therefore, they require different algorithms for detection. Distraction detection algorithms typically rely on either eye measures or driver performance measures because the effect of distraction on the coordination of measures has not been established. Combining both eye glance and vehicle data could enhance the ability of algorithms to detect and differentiate visual and cognitive distraction. The goal of this research is to examine whether poor coordination between visual behavior and vehicle control can identify diminished attention to driving in advance of breakdowns in lane keeping. The primary hypothesis of this dissertation is that detection of changes in eye-steering relationship caused by distraction could provide a prospective indication of vehicle state changes. Three specific aims are pursued to test this hypothesis. The first aim examines the effect of distracting activity on eye and steering movements to assess the degree to which the correlation parameters are indicative of distraction. The second aim applies a control-theoretic system identification approach to the eye movement and steering data to distinguish between distracted and non-distracted conditions. The third aim examines whether changes of eye-steering coordination associated with distraction provide a prospective indication of breakdowns in driver performance, i.e., lane departures. Together, the three aims show how that a combination of visual and steering behavior, i.e., eye-steering model, can differentiate between non-distracted and distracted state. This model revealed sensitivity to distraction associated with off-road glances. The models derived for different drivers have similar structure and fit to data from other drivers reasonably well. In addition, the differences in model order and model coefficients indicate the variability in driving behavior: some people generate more complex behavior than others. As was expected, eye-steering correlation on straight roads is not as strong as observed on curvy roads. However, eye-steering correlation measured through correlation coefficient and time delay between two movements is sensitive to different types of distraction. Time delay mediates changes in lane position and the eye-steering system predicts breakdowns in lane keeping. This dissertation contributes to developing a distraction detection system that integrates visual and steering behavior. More broadly, these results suggest that integrating eye and steering data can be helpful in detecting and mitigating impairments beyond distraction, such as those associated with alcohol, fatigue, and aging.
54

Fysiologiska korrelat av ögonrörelser och emotionell exponering hos friska individer : – en experimentundersökning av mekanismer i Eye Movement Desensitization and Reprocessing (EMDR)

Unger, Max Anders January 2008 (has links)
<p>Eye Movement Desensitization and Reprocessing, EMDR, har i psykoterapiforskning visats vara en effektiv behandlingsmetod av posttraumatiskt stressyndrom, PTSD. Däremot är ögonrörelsestimuleringen, som är ett centralt moment i metoden, kontroversiell och dess funktion inte klarlagd.</p><p>I föreliggande undersökning randomiserades trettiosex friska försökspersoner till en av tre stimuleringsbetingelser: ögonrörelsestimulering, taktil stimulering eller orörligt visuellt stimuli (kontrollgrupp). Stimuleringen kombinerades med imaginär exponering, negativ och positiv. Utfallet av experimentet mättes i olika fysiologiska mätparametrar, samt självskattningar av obehagsnivån (SUD). Resultaten visade signifikant högre hudkonduktansnivå vid ögonrörelsestimulering jämfört med kontrollgruppen, relaterat till aktivering av det sympatiska nervsystemet. Inga signifikanta gruppskillnader fanns i de övriga mätningarna. Mönstret av autonom aktivering kan tyda på att ögonrörelsestimuleringen utlöser eller förstärker en orienteringsrespons, vilket vissa teoretiker föreslagit är den verksamma mekanismen i EMDR. Dock behövs fortsatt forskning för att förstå denna verkan, samt koppling till terapeutisk effekt.</p>
55

Evaluating Readability on Mobile Devices

Öquist, Gustav January 2006 (has links)
<p>The thesis presents findings from five readability studies performed on mobile devices. The dynamic Rapid Serial Visual Presentation (RSVP) format has been enhanced with regard to linguistic adaptation and segmentation as well as eye movement modeling. The novel formats have been evaluated against other common presentation formats including Paging, Scrolling, and Leading in latin-square balanced repeated-measurement studies with 12-16 subjects. Apart from monitoring Reading speed, Comprehension, and Task load (NASA-TLX), Eye movement tracking has been used to learn more about how the text presentation affects reading.</p><p>The Page format generally offered best readability. Reading on a mobile phone decreased reading speed by 10% compared to reading on a Personal Digital Assistant (PDA), an interesting finding given that the display area of the mobile phone was 50% smaller. Scrolling, the most commonly used presentation format on mobile devices today, proved inferior to both Paging and RSVP. Leading, the most widely known dynamic format, caused very unnatural eye movements for reading. This seems to have increased task load, but not affected reading speed to a similar extent. The RSVP format displaying one word at time was found to reduce eye movements significantly, but contrary to common claims, this resulted in decreased reading speed and increased task load. In the last study, Predictive Text Presentation (PTP) was introduced. The format is based on RSVP and combines linguistic chunking and adaptation with eye movement modeling to achieve a reading experience that can rival traditional text presentation.</p><p>It is explained why readability on mobile devices is important, how it may be evaluated in an efficient and yet reliable manner, and PTP is pinpointed as the format with greatest potential for improvement. The methodology used in the evaluations and the shortcomings of the studies are discussed. Finally, a hyper-graeco-latin-square experimental design is proposed for future evaluations.</p>
56

In-between fixation and movement : on the generation of microsaccades and what they convey about saccade generation

Rolfs, Martin January 2007 (has links)
Microsaccades are an important component of the small eye movements that constitute fixation, the basis of visual perception. The specific function of microsaccades has been a long-standing research problem. Only recently, conclusive evidence emerged, showing that microsaccades aid both visual perception and oculomotor control. The main goal of this thesis was to improve our understanding of the implementation of microsaccade generation within the circuitry of saccade control, an unsolved issue in oculomotor research. We make a case for a model according to which microsaccades and saccades result from mutually dependent motor plans, competing for expression. The model consists of an activation field, coding for fixation at its center and for saccades at peripheral locations; saccade amplitude increases with eccentricity. Activity during fixation spreads to slightly peripheral locations in the field and, thus, may result in the generation of microsaccades. Inhibition of remote and excitation of neighbouring locations govern the dynamics of the field, resulting in a strong competition between fixation and saccade generation. We propose that this common-field model of microsaccade and saccade generation finds a neurophysiological counterpart in the motor map of the superior colliculus (SC), a key brainstem structure involved in the generation of saccades. In a series of five behavioral experiments, we tested implications of the model. Predictions were derived concerning (1) the behavior of microsaccades in a given task (microsaccade rate, amplitude, and direction), (2) the interactions of microsaccades and subsequent saccades, and (3) the relationship between microsaccadic behavior and neurophysiological processes at the level of the SC. The results yielded strong support for the model at all three levels of analysis, suggesting that microsaccade statistics are indicative of the state of the fixation-related part of the SC motor map. / Mikrosakkaden sind ein wichtiger Bestandteil der kleinen Augenbewegungen, aus denen Fixationen, die Basis der visuellen Wahrnehmung, bestehen. Neuere Arbeiten erbrachten schlüssige Evidenz dafür, das Mikrosakkaden eine wichtige Rolle in der Wahrnehmung und der Blickbewegungskontrolle spielen. Hauptanliegen dieser Dissertation war es, unser Verständnis der Implementierung der Generierung von Mikrosakkaden im Kreislauf der Sakkadensteuerung zu vertiefen. Wir schlagen ein Modell vor, in dem Mikrosakkaden und Sakkaden konkurrierende Bewegungsprogramme darstellen, die um ihre Umsetzung wettstreiten. Das Modell besteht aus einem Aktivationsfeld, in dem Fixation im Zentrum und Sakkaden in der Peripherie repräsentiert sind (Sakkadenamplitude steigt mit der Exzentrizität). Aktivität während der Fixation breitet sich zu leicht peripheren Orten im Feld aus und kann so zur Generierung von Mikrosakkaden führen. Hemmung von entfernten und Erregung von benachbarten Orten bestimmen die Dynamik im Feld, was zu einem starken Wettstreit zwischen Fixation und Sakkadengenerierung beiträgt. Wir schlagen vor, dass dieses common-field model of microsaccade and saccade generation ein neurophysiologisches Pendant in der Bewegungskarte des colliculus superior (CS) findet, einer Struktur im Hirnstamm, die im starken Zusammenhang mit der Entstehung von Sakkaden steht. In fünf behavioralen Experimenten wurden Implikationen des Modells überprüft. Vorhersagen wurden auf drei Ebenen abgeleitet: (1) Verhalten der Mikrosakkaden in bestimmten Aufgaben (Mikrosakkadenrate, -amplitude und -richtung), (2) Interaktionen von Mikrosakkaden und nachfolgenden Sakkaden, (3) der Zusammenhang zwischen Mikrosakkadenverhalten und neurophysiologischen Prozessen auf der Ebene des CS. Die Ergebnisse unterstützten das Modell auf allen drei Analyseebenen. Mikrosakkaden scheinen ein Indikator der Fixationsaktivität in der Bewegungskarte des CS zu sein.
57

Conditional co-occurrence probability acts like frequency in predicting fixation durations

Ong, James Kwan Yau, Kliegl, Reinhold January 2008 (has links)
The predictability of an upcoming word has been found to be a useful predictor in eye movement research, but is expensive to collect and subjective in nature. It would be desirable to have other predictors that are easier to collect and objective in nature if these predictors were capable of capturing the information stored in predictability. This paper contributes to this discussion by testing a possible predictor: conditional co-occurrence probability. This measure is a simple statistical representation of the relatedness of the current word to its context, based only on word co-occurrence patterns in data taken from the Internet. In the regression analyses, conditional co-occurrence probability acts like lexical frequency in predicting fixation durations, and its addition does not greatly improve the model fits. We conclude that readers do not seem to use the information contained within conditional co-occurrence probability during reading for meaning, and that similar simple measures of semantic relatedness are unlikely to be able to replace predictability as a predictor for fixation durations. Keywords: Co-occurrence probability, Cloze predictability, frequency, eye movement, fixation duration.
58

Evaluating Readability on Mobile Devices

Öquist, Gustav January 2006 (has links)
The thesis presents findings from five readability studies performed on mobile devices. The dynamic Rapid Serial Visual Presentation (RSVP) format has been enhanced with regard to linguistic adaptation and segmentation as well as eye movement modeling. The novel formats have been evaluated against other common presentation formats including Paging, Scrolling, and Leading in latin-square balanced repeated-measurement studies with 12-16 subjects. Apart from monitoring Reading speed, Comprehension, and Task load (NASA-TLX), Eye movement tracking has been used to learn more about how the text presentation affects reading. The Page format generally offered best readability. Reading on a mobile phone decreased reading speed by 10% compared to reading on a Personal Digital Assistant (PDA), an interesting finding given that the display area of the mobile phone was 50% smaller. Scrolling, the most commonly used presentation format on mobile devices today, proved inferior to both Paging and RSVP. Leading, the most widely known dynamic format, caused very unnatural eye movements for reading. This seems to have increased task load, but not affected reading speed to a similar extent. The RSVP format displaying one word at time was found to reduce eye movements significantly, but contrary to common claims, this resulted in decreased reading speed and increased task load. In the last study, Predictive Text Presentation (PTP) was introduced. The format is based on RSVP and combines linguistic chunking and adaptation with eye movement modeling to achieve a reading experience that can rival traditional text presentation. It is explained why readability on mobile devices is important, how it may be evaluated in an efficient and yet reliable manner, and PTP is pinpointed as the format with greatest potential for improvement. The methodology used in the evaluations and the shortcomings of the studies are discussed. Finally, a hyper-graeco-latin-square experimental design is proposed for future evaluations.
59

Fysiologiska korrelat av ögonrörelser och emotionell exponering hos friska individer : – en experimentundersökning av mekanismer i Eye Movement Desensitization and Reprocessing (EMDR)

Unger, Max Anders January 2008 (has links)
Eye Movement Desensitization and Reprocessing, EMDR, har i psykoterapiforskning visats vara en effektiv behandlingsmetod av posttraumatiskt stressyndrom, PTSD. Däremot är ögonrörelsestimuleringen, som är ett centralt moment i metoden, kontroversiell och dess funktion inte klarlagd. I föreliggande undersökning randomiserades trettiosex friska försökspersoner till en av tre stimuleringsbetingelser: ögonrörelsestimulering, taktil stimulering eller orörligt visuellt stimuli (kontrollgrupp). Stimuleringen kombinerades med imaginär exponering, negativ och positiv. Utfallet av experimentet mättes i olika fysiologiska mätparametrar, samt självskattningar av obehagsnivån (SUD). Resultaten visade signifikant högre hudkonduktansnivå vid ögonrörelsestimulering jämfört med kontrollgruppen, relaterat till aktivering av det sympatiska nervsystemet. Inga signifikanta gruppskillnader fanns i de övriga mätningarna. Mönstret av autonom aktivering kan tyda på att ögonrörelsestimuleringen utlöser eller förstärker en orienteringsrespons, vilket vissa teoretiker föreslagit är den verksamma mekanismen i EMDR. Dock behövs fortsatt forskning för att förstå denna verkan, samt koppling till terapeutisk effekt.
60

Why Do Young Children Fail in False Belief Tasks: Linguistic Representations and Implicit Processing

Yi, Li January 2009 (has links)
<p>Despite recent evidence that infants under one year of age have implicit understanding of theory of mind, three-year-old children repeatedly fail in traditional false belief tasks. A serious of 4 studies investigated two possible sources of errors. First, children's comprehension of theory of mind questions was tested in an elicited imitation task. Second, their understanding of mental events was measured using anticipatory eye movements in non-verbal tasks. Results showed that young children's performance in verbal false belief tasks is limited by their understanding of linguistic representations of beliefs and their ability to monitor mental states in real-time. This implies the limitations of young children in keeping track of complex social events in real time and in understanding language conventions in real time.</p> / Dissertation

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