No description available.

Athletes are at risk of sustaining a concussion in all sports and at all competitive levels which may lead to balance impairments. Balance results from the integration of visual, vestibular, and somatosensory information. The underlying pathophysiology for balance impairments is not well understood and visuo-motor processing impairments and how these impairments contribute to balance in concussed athletes has not been reported. Objectives: (1) to investigate the influence of visual perturbation on upright postural stability and balance in athletes who have recently suffered a sports-related concussion, (2) to establish the test-retest reliability of a simple visuo-motor processing task. Design: A longitudinal, cohort design. Setting: University research laboratory. Subjects: Fourteen interscholastic, club, and intercollegiate athletes (8 males, 6 females, age 17.21±2.97 years, height 176.43±12.73cm, mass 75.55±22.76kg) participated. Seven subjects with acute concussions (injury) were matched to seven control subjects. Intervention(s): All subjects completed a simple visuo-motor processing task (SVMP), Sensory Organization Test (SOT), and modified Clinical Test of Sensory Interaction in Balance (mCTSIB). Each subject’s balance was tested under two visual testing conditions: (1) standard testing methods with normal visual fields, and (2) visual distraction through optical flow motion using a computer-generated optical flow pattern. Testing was done 24-48 hours and ten days following injury. The order of the testing was counterbalanced (standard protocol or visual distraction) and day of testing. Main Outcome Measures: Reaction time, accuracy, number of errors on SVMP; composite equilibrium score, sensory system preference on SOT; and mean center of gravity sway velocity on mCTSIB. Results: Significant impairments were noted on day 1 of testingcompared to day 10 for SVMP reaction time (day 1=496.18±52.82ms, day 10=439.01±20.62ms, F=4.72, p=0.01), and SOT composite equilibrium score standard (day 1=73.14±5.73, day 10=83.57±2.15, F=7.60, p<0.001). Conclusion: Physiological changes occur immediately following concussions that affect the visual system, more specifically, visuo-motor processing. The SVMP task provides unique information about visuo-motor processing following a concussion that is not currently being assessed. Visuo-motor processing is correlated with upright balance and should be evaluated following a sports-related concussion.

Image format (Laws, Adlington, Gale, Moreno-Martínez, & Sartori, 2007), ceiling effects in controls (Fung et al., 2001; Laws et al., 2005; Moreno-Martínez, & Laws, 2007; 2008), and nuisance variables (Funnell & De Mornay Davis, 1996; Funnell & Sheridan, 1992; Stewart, Parkin & Hunkin, 1992) all influence the emergence of category specific deficits in Alzheimer‟s dementia (AD). Thus, the predominant use of line drawings of familiar, everyday items in category specific research is problematic. Moreover, this does not allow researchers to explore the extent to which format may influence object recognition. As such, the initial concern of this thesis was the development of a new corpus of 147 colour images of graded naming difficulty, the Hatfield Image Test (HIT; Adlington, Laws, & Gale, 2009), and the collection of relevant normative data including ratings of: age of acquisition, colour diagnosticity, familiarity, name agreement, visual complexity, and word frequency. Furthermore, greyscale and line-drawn versions of the HIT corpus were developed (and again, the associated normative data obtained), to permit research into the influence of image format on the emergence of category specific effects in patients with AD, and in healthy controls. Using the HIT, several studies were conducted including: (i) a normative investigation of the effects of category and image format on naming accuracy and latencies in healthy controls; (ii) an exploration of the effects of image format (using the HIT images presented in colour, greyscale, and line-drawn formats) and category on the naming performance of AD patients, and age-matched controls performing below ceiling; (iii) a longitudinal investigation comparing AD patient performance to that of age-matched controls, on a range of semantic tasks (naming, sorting, word-picture matching), using colour, greyscale, and line-drawn versions of the HIT; (iv) a comparison of naming in AD patients and age-matched controls on the HIT and the (colour, greyscale and line-drawn) images from the Snodgrass and Vanderwart (1980) corpus; and (v) a meta-analysis to explore category specific naming in AD using the Snodgrass and Vanderwart (1980) versus other corpora. Taken together, the results of these investigations showed first, that image format interacts with category. For both AD patients and controls, colour is more important for the recognition of living things, with a significant nonliving advantage emerging for the line-drawn images, but not the colour images. Controls benefitted more from additional surface information than AD patients, which chapter 6 shows results from low-level visual cortical impairment in AD. For controls, format was also more important for the recognition of low familiarity, low frequency items. In addition, the findings show that adequate control data affects the emergence of category specific deficits in AD. Specifically, based on within-group comparison chapters 6, 7, and 8 revealed a significant living deficit in AD patients. However, when compared to controls performing below ceiling, as demonstrated in chapters 7 and 8, this deficit was only significant for the line drawings, showing that the performance observed in AD patients is simply an exaggeration of the norm.

O presente estudo teve como objetivo investigar possíveis alterações na percepção visual relacionadas à depressão maior. Para tanto, realizou-se medidas de sensibilidade ao contraste (SC), uma das ferramentas mais utilizadas na avaliação teórica e clínica do sistema visual humano. A SC tem se estabelecido como uma técnica que permite estudar e identificar a forma como determinadas patologias acometem a visão e o sistema nervoso central. Participaram deste estudo 33 voluntários, com idades entre 19 e 37 anos e acuidade visual normal ou corrigida. Dentre eles, 11 foram diagnosticados com transtorno depressivo maior, segundo os critérios do DSM-IV e se encontravam devidamente medicados (Grupo Depressão - GD). Os outros 22 eram isentos de patologia neuropsiquiátrica e gozavam de boa saúde (Grupo Controle - GC). A SC foi mensurada através do método psicofísico da escolha forçada entre duas alternativas temporais (2AF). Foram testadas as frequências espaciais lineares de 0,5; 2,5; 10 e 20 ciclos por grau de ângulo visual (cpg) e as angulares de 2, 4, 24, 48 e 96 ciclos/360º. Os estímulos eram circulares e foram apresentados em um monitor de vídeo LG, RGB de 19 polegadas (resolução de tela de 1024 x 768 pixels a 75 Hz) conectado a um microcomputador e um BITS ++ (Cambridge Research Systems). A luminância média da tela foi de 41,05 cd/m² mensurada por um fotômetro ColorCAL (Cambridge Research Systems). As medidas foram realizadas a uma distância de 300 cm da tela do monitor. Os estímulos foram exibidos em pares sucessivos, um com a frequência testada (espaciais lineares ou angulares) e o outro era um círculo cinza com luminância homogênea. Os participantes foram orientados a pressionar o botão do lado esquerdo do mouse, quando o estímulo teste fosse apresentado primeiro, e o botão do lado direito, quando fosse apresentado depois do estímulo com luminância homogênea. Os resultados mostraram um efeito de interação para as frequências espaciais lineares [F(3, 93) = 6,0814, p = 0,0008], o test post-hoc Newmann Kels mostrou diferença significante na frequência de 0,5 cpg. Os resultados para as frequências angulares mostraram um efeito de interação marginalmente significante. As análises com post-hoc mostraram uma diferença marginalmente significante para frequência de 2 ciclos/360º. Esses resultados sugerem alterações na SC de pacientes com depressão maior medicados / The present study aimed to investigate potential changes in visual perception related to major depression. Then, we measure of contrast sensitivity (CS), one of the most used tools to study the humans visual system. The CS has established itself as one tool that allows to study and identify how certain diseases affect the vision and the central nervous system. The study included 33 volunteers aged between 19 and 37 years and they are normal or corrected visual acuity. 11 were diagnosed with major depressive disorder according to DSM-IV and were treated with antidepressants (Depression Group - DG). The other 22 were free of neuropsychiatric disease and were in good health (Control Group - CG). The CS was measured using the psychophysical method of forced choice between two temporal alternatives (2AF). Were tested linear spatial frequencies of 0.5, 2.5, 10 and 20 cycles per degree of visual angle (cpd) and the angular frequencies of 2, 4, 24, 48 and 96 cycles/360º. The stimuli were circular and were presented on a video monitor LG 19-inch RGB (screen resolution of 1024 x 768 pixels at 75 Hz) connected to a microcomputer and a BITS + + (Cambridge Research Systems). The average luminance of the display was 41.05 cd / m² measured by a photometer ColorCal (Cambridge Research Systems). The measurements were performed at a distance of 300 cm from the monitor screen. The stimuli were displayed in successive pairs, with a frequency tested (linear or angular) and the other was a gray circle with uniform luminance. Participants were instructed to press the left mouses button when the test stimulus was presented first, and the right button when the stimulus was presented second. The results showed an interaction effect for the linear spatial frequency [F (3, 93) = 6.0814, p = 0.0008], the test post-hoc Newmann Kels showed significant difference in frequency of 0.5 cpd. The results for the angular frequencies showed a marginally significant effect of interaction. The analyzes with post-hoc showed a marginally significant difference for frequency of 2 cycles/360º. These results suggest changes in the CS of patients with major depression medicated

A presente dissertação investigou a relação entre estilo cognitivo verbal-visual, recordação e expressão narrativa de eventos autobiográficos. Cento e quatro estudantes universitários realizaram as seguintes tarefas: 1) Relato de Evento Autobiográfico; 2) Questionário de Memória Autobiográfica (QMA); 3) Questionário Verbalizador-visualizador (QVV); e 4) versão reduzida do Bett´s Questionnarie Upon Mental Imagery. A análise fatorial do Estudo I distinguiu dois níveis da recordação de eventos pessoais: 1) processos cognitivos pouco dependentes de recursos reflexivos e concomitantes ao ato de recordar, como a vivacidade de imagens; e 2) processos reflexivos, nos quais se destacam as avaliações e juízos acerca da importância do evento. O Estudo II indicou a inconsistência empírica do fator visual do QVV e a adequação psicométrica do fator que avalia preferências cognitivas verbais. O Estudo III não confirmou a expectativa de correlação entre preferências cognitivas (por palavras ou por imagens) e memória autobiográfica (tanto na recordação quanto no relato de eventos pessoais). No entanto, o teste t revelou diferenças significativas (p>0,01) entre dois grupos (Psicologia e Letras versus Odontologia e Biomedicina) quanto às variáveis: escore em estilo verbal, número de palavras e coerência narrativa. O grupo Psicologia e Letras apresentou os maiores escores nas três variáveis. Os resultados sugeriram a existência de um construto que abarca tanto estilo cognitivo verbal quanto características narrativas: perfil cognitivo verbalnarrativo. A análise quantitativa/qualitativa do Estudo IV apontou a proporção equilibrada entre descritores objetivos e subjetivos como condição para a obtenção de alta coerência narrativa. Além disso, verificou-se que características verbais e narrativas estavam alicerçadas em habilidades imaginativas. Este achado contradiz a freqüente concepção de que preferências verbais e imaginativas seriam polaridades excludentes, indicando interação entre estes dois processos cognitivos. / This research investigated the relationship among verbalizer-visualizer cognitive style, recall, and narrative expression of autobiographical events. One hundred and four undergraduate students were asked to complete four tasks: 1) Report of an Autobiographical Event; 2) Autobiographical Memory Questionnaire (AMQ); 3) Verbalizer-visualizer Questionnaire (VVQ); 4) Bett´s Questionnarie Upon Mental Imagery – Short Version. Factorial Analisys of Study I distinguished two factors in recalling of personal events: 1) pre-reflexive cognitive processes (poorly dependent on reflexive resources, such as imagery vivacity); 2) reflexive cognitive processes (such as evaluations concerning the event significance). Outcomes of Study II highlighted an empirical inconsistency of the visual factor of VVQ and appropriate psychometric properties of its verbal scores. In Study III the expected correlation between cognitive preferences (for words or images) and autobiographical memory (for recall and report of personal events) was not confirmed. However, a t test analysis indicated significant difference (p>0,01) between two groups (Psychology and Languages versus Odontology and Biomedicine) concerning the following variables: verbal scores, narrative coherence and narrative volume. Psychology and Languages students presented higher scores in such variables. A new construct is suggested in order to explain both verbal cognitive style and narrative characteristics: the verbal-narrative cognitive profile. Qualitative/quantitative analysis in Study IV indicated that a similar balance between objective and subjective narrative descriptors is needed to achieve high levels of narrative coherence. Moreover, it was observed that verbal and narrative characteristics depend upon imaginative skills. Thus, outcomes contradict the ordinary assumption that verbal and imaginative preferences should be taken as excluding polarities: an interaction between these two cognitive processes was found.

This study investigates a phenomenon that I have termed occlusion inhibition. This research and a small number of earlier studies suggest that, in some experimental conditions, when an attended (target) object is partially occluded by a distractor object, there is less attention allocated to the occluded region of the target object than to the visible parts of that object. In the literature, there are mixed results concerning this attentional effect. Some studies find it and others do not. This study investigates the differences between those conflicting studies with the goal of identifying the factor or factors that govern when occlusion inhibition occurs. Evidence is presented to rule out a number of potentially relevant factors such as depth perception, figural complexity, set size, the use of real world vs. abstract geometric objects, the position of occlusion, the number of overlaps in the display, and the adoption of the attend-object paradigm over the spatial cueing paradigm. After all these factors are ruled out, Experiments 3 and 4 provide evidence for a factor that does determine whether occlusion inhibition occurs or not. These two experiments differ only in the fact that participants are required to report the border color of the target object in Experiment 3 and not in Experiment 4. This task was designed to ensure that participants fully attend to the target object. Occlusion inhibition occurs when the target color is reported, but not when no target color report is required. Removing the target reporting task was found to be an effective means of turning occlusion inhibition on and off. The results of these experiments suggest that, if occlusion inhibition is to take place, attentional selection of overlapping figures requires the target object to be fully processed. This conclusion in turn suggests that attention does not automatically exclude the irrelevant portions of occluded objects, but that attention selects the entire location of the object and then, through reiterative feedback mechanisms, fine tunes the information to inhibit areas that do not belong to the object.

A presente dissertação investigou a relação entre estilo cognitivo verbal-visual, recordação e expressão narrativa de eventos autobiográficos. Cento e quatro estudantes universitários realizaram as seguintes tarefas: 1) Relato de Evento Autobiográfico; 2) Questionário de Memória Autobiográfica (QMA); 3) Questionário Verbalizador-visualizador (QVV); e 4) versão reduzida do Bett´s Questionnarie Upon Mental Imagery. A análise fatorial do Estudo I distinguiu dois níveis da recordação de eventos pessoais: 1) processos cognitivos pouco dependentes de recursos reflexivos e concomitantes ao ato de recordar, como a vivacidade de imagens; e 2) processos reflexivos, nos quais se destacam as avaliações e juízos acerca da importância do evento. O Estudo II indicou a inconsistência empírica do fator visual do QVV e a adequação psicométrica do fator que avalia preferências cognitivas verbais. O Estudo III não confirmou a expectativa de correlação entre preferências cognitivas (por palavras ou por imagens) e memória autobiográfica (tanto na recordação quanto no relato de eventos pessoais). No entanto, o teste t revelou diferenças significativas (p>0,01) entre dois grupos (Psicologia e Letras versus Odontologia e Biomedicina) quanto às variáveis: escore em estilo verbal, número de palavras e coerência narrativa. O grupo Psicologia e Letras apresentou os maiores escores nas três variáveis. Os resultados sugeriram a existência de um construto que abarca tanto estilo cognitivo verbal quanto características narrativas: perfil cognitivo verbalnarrativo. A análise quantitativa/qualitativa do Estudo IV apontou a proporção equilibrada entre descritores objetivos e subjetivos como condição para a obtenção de alta coerência narrativa. Além disso, verificou-se que características verbais e narrativas estavam alicerçadas em habilidades imaginativas. Este achado contradiz a freqüente concepção de que preferências verbais e imaginativas seriam polaridades excludentes, indicando interação entre estes dois processos cognitivos. / This research investigated the relationship among verbalizer-visualizer cognitive style, recall, and narrative expression of autobiographical events. One hundred and four undergraduate students were asked to complete four tasks: 1) Report of an Autobiographical Event; 2) Autobiographical Memory Questionnaire (AMQ); 3) Verbalizer-visualizer Questionnaire (VVQ); 4) Bett´s Questionnarie Upon Mental Imagery – Short Version. Factorial Analisys of Study I distinguished two factors in recalling of personal events: 1) pre-reflexive cognitive processes (poorly dependent on reflexive resources, such as imagery vivacity); 2) reflexive cognitive processes (such as evaluations concerning the event significance). Outcomes of Study II highlighted an empirical inconsistency of the visual factor of VVQ and appropriate psychometric properties of its verbal scores. In Study III the expected correlation between cognitive preferences (for words or images) and autobiographical memory (for recall and report of personal events) was not confirmed. However, a t test analysis indicated significant difference (p>0,01) between two groups (Psychology and Languages versus Odontology and Biomedicine) concerning the following variables: verbal scores, narrative coherence and narrative volume. Psychology and Languages students presented higher scores in such variables. A new construct is suggested in order to explain both verbal cognitive style and narrative characteristics: the verbal-narrative cognitive profile. Qualitative/quantitative analysis in Study IV indicated that a similar balance between objective and subjective narrative descriptors is needed to achieve high levels of narrative coherence. Moreover, it was observed that verbal and narrative characteristics depend upon imaginative skills. Thus, outcomes contradict the ordinary assumption that verbal and imaginative preferences should be taken as excluding polarities: an interaction between these two cognitive processes was found.

A presente dissertação investigou a relação entre estilo cognitivo verbal-visual, recordação e expressão narrativa de eventos autobiográficos. Cento e quatro estudantes universitários realizaram as seguintes tarefas: 1) Relato de Evento Autobiográfico; 2) Questionário de Memória Autobiográfica (QMA); 3) Questionário Verbalizador-visualizador (QVV); e 4) versão reduzida do Bett´s Questionnarie Upon Mental Imagery. A análise fatorial do Estudo I distinguiu dois níveis da recordação de eventos pessoais: 1) processos cognitivos pouco dependentes de recursos reflexivos e concomitantes ao ato de recordar, como a vivacidade de imagens; e 2) processos reflexivos, nos quais se destacam as avaliações e juízos acerca da importância do evento. O Estudo II indicou a inconsistência empírica do fator visual do QVV e a adequação psicométrica do fator que avalia preferências cognitivas verbais. O Estudo III não confirmou a expectativa de correlação entre preferências cognitivas (por palavras ou por imagens) e memória autobiográfica (tanto na recordação quanto no relato de eventos pessoais). No entanto, o teste t revelou diferenças significativas (p>0,01) entre dois grupos (Psicologia e Letras versus Odontologia e Biomedicina) quanto às variáveis: escore em estilo verbal, número de palavras e coerência narrativa. O grupo Psicologia e Letras apresentou os maiores escores nas três variáveis. Os resultados sugeriram a existência de um construto que abarca tanto estilo cognitivo verbal quanto características narrativas: perfil cognitivo verbalnarrativo. A análise quantitativa/qualitativa do Estudo IV apontou a proporção equilibrada entre descritores objetivos e subjetivos como condição para a obtenção de alta coerência narrativa. Além disso, verificou-se que características verbais e narrativas estavam alicerçadas em habilidades imaginativas. Este achado contradiz a freqüente concepção de que preferências verbais e imaginativas seriam polaridades excludentes, indicando interação entre estes dois processos cognitivos. / This research investigated the relationship among verbalizer-visualizer cognitive style, recall, and narrative expression of autobiographical events. One hundred and four undergraduate students were asked to complete four tasks: 1) Report of an Autobiographical Event; 2) Autobiographical Memory Questionnaire (AMQ); 3) Verbalizer-visualizer Questionnaire (VVQ); 4) Bett´s Questionnarie Upon Mental Imagery – Short Version. Factorial Analisys of Study I distinguished two factors in recalling of personal events: 1) pre-reflexive cognitive processes (poorly dependent on reflexive resources, such as imagery vivacity); 2) reflexive cognitive processes (such as evaluations concerning the event significance). Outcomes of Study II highlighted an empirical inconsistency of the visual factor of VVQ and appropriate psychometric properties of its verbal scores. In Study III the expected correlation between cognitive preferences (for words or images) and autobiographical memory (for recall and report of personal events) was not confirmed. However, a t test analysis indicated significant difference (p>0,01) between two groups (Psychology and Languages versus Odontology and Biomedicine) concerning the following variables: verbal scores, narrative coherence and narrative volume. Psychology and Languages students presented higher scores in such variables. A new construct is suggested in order to explain both verbal cognitive style and narrative characteristics: the verbal-narrative cognitive profile. Qualitative/quantitative analysis in Study IV indicated that a similar balance between objective and subjective narrative descriptors is needed to achieve high levels of narrative coherence. Moreover, it was observed that verbal and narrative characteristics depend upon imaginative skills. Thus, outcomes contradict the ordinary assumption that verbal and imaginative preferences should be taken as excluding polarities: an interaction between these two cognitive processes was found.

O presente estudo teve como objetivo investigar possíveis alterações na percepção visual relacionadas à depressão maior. Para tanto, realizou-se medidas de sensibilidade ao contraste (SC), uma das ferramentas mais utilizadas na avaliação teórica e clínica do sistema visual humano. A SC tem se estabelecido como uma técnica que permite estudar e identificar a forma como determinadas patologias acometem a visão e o sistema nervoso central. Participaram deste estudo 33 voluntários, com idades entre 19 e 37 anos e acuidade visual normal ou corrigida. Dentre eles, 11 foram diagnosticados com transtorno depressivo maior, segundo os critérios do DSM-IV e se encontravam devidamente medicados (Grupo Depressão - GD). Os outros 22 eram isentos de patologia neuropsiquiátrica e gozavam de boa saúde (Grupo Controle - GC). A SC foi mensurada através do método psicofísico da escolha forçada entre duas alternativas temporais (2AF). Foram testadas as frequências espaciais lineares de 0,5; 2,5; 10 e 20 ciclos por grau de ângulo visual (cpg) e as angulares de 2, 4, 24, 48 e 96 ciclos/360º. Os estímulos eram circulares e foram apresentados em um monitor de vídeo LG, RGB de 19 polegadas (resolução de tela de 1024 x 768 pixels a 75 Hz) conectado a um microcomputador e um BITS ++ (Cambridge Research Systems). A luminância média da tela foi de 41,05 cd/m² mensurada por um fotômetro ColorCAL (Cambridge Research Systems). As medidas foram realizadas a uma distância de 300 cm da tela do monitor. Os estímulos foram exibidos em pares sucessivos, um com a frequência testada (espaciais lineares ou angulares) e o outro era um círculo cinza com luminância homogênea. Os participantes foram orientados a pressionar o botão do lado esquerdo do mouse, quando o estímulo teste fosse apresentado primeiro, e o botão do lado direito, quando fosse apresentado depois do estímulo com luminância homogênea. Os resultados mostraram um efeito de interação para as frequências espaciais lineares [F(3, 93) = 6,0814, p = 0,0008], o test post-hoc Newmann Kels mostrou diferença significante na frequência de 0,5 cpg. Os resultados para as frequências angulares mostraram um efeito de interação marginalmente significante. As análises com post-hoc mostraram uma diferença marginalmente significante para frequência de 2 ciclos/360º. Esses resultados sugerem alterações na SC de pacientes com depressão maior medicados / The present study aimed to investigate potential changes in visual perception related to major depression. Then, we measure of contrast sensitivity (CS), one of the most used tools to study the humans visual system. The CS has established itself as one tool that allows to study and identify how certain diseases affect the vision and the central nervous system. The study included 33 volunteers aged between 19 and 37 years and they are normal or corrected visual acuity. 11 were diagnosed with major depressive disorder according to DSM-IV and were treated with antidepressants (Depression Group - DG). The other 22 were free of neuropsychiatric disease and were in good health (Control Group - CG). The CS was measured using the psychophysical method of forced choice between two temporal alternatives (2AF). Were tested linear spatial frequencies of 0.5, 2.5, 10 and 20 cycles per degree of visual angle (cpd) and the angular frequencies of 2, 4, 24, 48 and 96 cycles/360º. The stimuli were circular and were presented on a video monitor LG 19-inch RGB (screen resolution of 1024 x 768 pixels at 75 Hz) connected to a microcomputer and a BITS + + (Cambridge Research Systems). The average luminance of the display was 41.05 cd / m² measured by a photometer ColorCal (Cambridge Research Systems). The measurements were performed at a distance of 300 cm from the monitor screen. The stimuli were displayed in successive pairs, with a frequency tested (linear or angular) and the other was a gray circle with uniform luminance. Participants were instructed to press the left mouses button when the test stimulus was presented first, and the right button when the stimulus was presented second. The results showed an interaction effect for the linear spatial frequency [F (3, 93) = 6.0814, p = 0.0008], the test post-hoc Newmann Kels showed significant difference in frequency of 0.5 cpd. The results for the angular frequencies showed a marginally significant effect of interaction. The analyzes with post-hoc showed a marginally significant difference for frequency of 2 cycles/360º. These results suggest changes in the CS of patients with major depression medicated

La connaissance orthographique des mots est indispensable au développement d’une lecture experte et rapide et d’une écriture correcte. L’acquisition de ces connaissances orthographiques lexicales est un processus complexe, encore mal compris. Cette acquisition se ferait en grande partie de façon implicite au cours de la lecture. Elle dépendrait alors de la qualité du décodage, d’autres facteurs restant à préciser. Des données théoriques et certains premiers résultats empiriques ont suggéré que le traitement visuel simultané de toutes les lettres du mot est un facteur important pour l’acquisition de son orthographe spécifique. Dans ce travail de thèse, cette hypothèse est testée d’une part par des études de régression, d’autre part par des études expérimentales. Les analyses de régression étudient le lien entre l’empan visuo-attentionnel (EVA), estimant les capacités maximales de traitement visuel simultané, et les connaissances orthographiques lexicales. Les résultats montrent une relation significative entre l’EVA et les connaissances orthographiques lexicales lorsque celles-ci sont évaluées par une épreuve de production écrite ou par un test d’auto-apprentissage. Cette relation est spécifique aux connaissances lexicales puisqu’elle ne se généralise pas à l’orthographe grammaticale. Elle existe indépendamment des capacités de mémoire de travail visuo-spatiale et de lecture. Les études expérimentales, tant chez l’enfant que chez l’adulte, explorent toutes le rôle du traitement visuel simultané sur l’acquisition des connaissances orthographiques en situation d’auto-apprentissage. Cette exploration est conduite en contrastant, pendant une lecture de mots nouveaux, une condition expérimentale où le traitement visuel simultané est possible avec une autre condition où ce type de traitement est impossible. Les résultats mettent en évidence un avantage de la condition avec traitement visuel simultané possible, sur la mémorisation de l’orthographe des mots nouveaux. Cet avantage n’est pas dû à des différences de temps de présentation ou de temps de traitement des items entre les deux conditions et confirme donc que, au-delà des capacités de lecture-décodage, les capacités de traitement visuel simultané sont directement impliquées dans l’acquisition des connaissances orthographiques lexicales. / Word orthographic knowledge is necessary to develop expert and fast reading and correct orthographic production. Lexical orthographic acquisition is a complex and largely unknown process. This acquisition is mostly implicit during reading. It would depend on phonological decoding and on other factors not précised yet. Both theoretical and empirical data suggest that the simultaneous visual processing made during word reading could influence lexical orthographic acquisition. This hypothesis is assessed with both regression analyses and experimental studies. Regression analyses examine the relation between visual attention span (VAS), which estimates the maximal simultaneous processing abilities, and the lexical orthographic knowledge. Results show a significant relation between VAS and lexical orthographic knowledge when this knowledge is assessed with a dictation task or with a self-teaching test. This relation is specific because it doesn’t extent to grammatical orthographic knowledge. It exists independently of both visual-spatial working memory and reading skills. Experimental studies, both on children and adults, investigate the role of simultaneous visual processing on lexical orthographic acquisition during self-teaching. This investigation was done with two experimental conditions during the reading of novel words. In the whole word condition, the entire letter-string of a novel word was available at once, while in the partial word condition only sub-lexical parts of the word letter string were available at once. The results show an advantage of the whole word condition on the memorization of novel word orthographic forms. This advantage is not explained by differences of presentation time or of processing time between the two conditions, and confirms that, beyond the phonological decoding skills, simultaneous visual processing abilities of entire words are involved in lexical orthographic acquisition.