Etudier les fonctions cognitives qui caractérisent l’intelligence humaine et animale


Accueil > LPC > Séminaires

2014/15

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SÉMINAIRES À VENIR HISTORIQUE DES SÉMINAIRES

 

10 octobre 2014 - 16h 
Manuel Carreiras (BLRI)

14 novembre 2014
Hirofumi Saito

21 novembre 2014
Nicolas Claidière

28 novembre 2014 - 10h30
Eleanor Maguire

11 décembre 2014 - 14h
Thèse Laure Pourcin

12 décembre 2014
Kumiko Fukumura  (BLRI ?) (cf F-X A)

15 décembre 2014 - 14h30
Thèse Julien Taillan

19  décembre 2014
Journée d’Etude Fed3C

09 janvier 2015
Repas LPC

23 janvier 2015 - 10h
Laurence Casini  HDR

30 janvier 2015
Veronica Montani 

6 février 2015 - 16h
Mathieu Declerck BLRI

20 mars 2015
Louisa Bogaerts

27 mars 2015
Royce Anders

02 avril 2015 (Jeudi) - 10h-12h
Jamie Campbell / Valérie Thompson.

23 avril 2015 (Jeudi) - 14h
Soutenance de thèse Delphine Massendari

12 juin 2015
Mieke Donk

19 juin 2015
Valérie Camos

Secrétariat : Aline.Pelissier@univ-amu.fr
Sauf indications contraires, le séminaire LPC/FR3C se déroule de 11h à 12h30 et le séminaire LPC/BLRI de 16h à 17h et plus .... Salle des Voûtes FR3C

 

Vendredi 10 Octobre - 16h
(Amphi Massiani (de chimie), Centre St Charles, Marseille) BLRI

Manuel Carreiras
(Basque Center on Cognition, Brain and Language, Donostia-San Sebastián, Spain ; IKERBASQUE. Basque Foundation for Science. Bilbao. Spain)

The bilingual brain : Plasticity and processing from cradle to grave.

Most people either learn more than one language from birth or invest quite a lot of time and effort learning a second language. Bilingualism and second language learning is an interesting case for investigating cognitive and brain plasticity. In this talk I will describe behavioral and neuroimaging evidence on the cognitive and brain mechanisms adults and infants (monlinguals, bilinguals and second language learners) use for processing language. In particular I will address whether proficient second language learners use similar or different brain mechanisms during processing and what are the neural consequences (structural and functional) of dealing with two languages.

 

 

Vendredi 14 Novembre - 11h-12h
(Salle des Voûtes, Féd3C, Centre St Charles, Marseille)

Hirofumi SAITO
(Nagoya University, Unit of Cognitive Informatics, Japan)

Delicate truth and falsehood in multi-brain communication : Near Infrared Spectroscopy studies

Cognitive studies in psychology have been affected through winds of brilliant innovation of measurement technology. One of the most remarkable advances in cognitive neuroscience is brain imaging techniques. The purpose of the present talk is to introduce the trend of brain imaging studies, especially focusing on NIRS (Near infrared spectroscopy) studies.
Despite continued vigorous exertion in neuroimaging studies, little is known about the brain activation changes during the complex dynamic movements to be evaluated in daily life.
One of the reasons for the current lack of progress in elucidating these activating changes stems from the limitation of neuroimaging techniques such as fMRI and positron emission tomography (PET) that are unable to assess cortical function in ambulant participants.
Unlike other neuroimaging techniques, NIRS has few physical constraints on the participant and is tolerant to motion artifact, which permits serial assessments of tasks in relaxed and realistic environments. In particular, a new 2-channel NIRS unit, named PocketNIRS, is highly portable due to its size (length : 100 mm ; width : 61 mm ; thickness : 18.5 mm) and weight (100 g including the batteries), and provides mobility for participants by transmitting the hemodynamic signals wirelessly via Bluetooth.
More recently, the increasing number of flexible probe arrangements in multi-channel NIRS enables hyper-scanning. That is, two participants can interact while we simultaneously measure the brain activities of both participants and examine their social interaction.
We introduce our four NIRS studies according to a combination of scanning type (hyper-scanning or not) and portable type (wireless or not). The designed contents in the present talk are the following : After demonstrating a brief overview of NIRS, (1) Speech and Gesture study (single brain with dual task), (2) Cooperation and Competition (turn taking computer game), (3) Integration of emotion and cognition for artwork (like-understanding task), (4) Deception and lie detection (face to face lying task).

 

 Vendredi 21 Novembre - 11h-12h
(Salle des Voûtes, Féd3C, Centre St Charles, Marseille)

Nicolas CLAIDIERE
(LPC, Cognition Comparée, Marseille)

The effect of psychological mechanisms on cultural evolution

In the study of cultural evolution, biologists and anthropologists sometimes overlook, or minimise, the role of psychology. At the same time, psychologists rarely study the consequences of psychological mechanisms at a scale that is commensurate to that of cultural evolution. I will describe studies in human and non-human primates that have a common theme : understanding psychology is essential to study cultural evolution because the effect of psychological mechanisms is amplified during the transmission of information between individuals. In particular, I will describe our first attempt at developing an experimental system with baboons that may address important questions regarding the cultural evolution of language. For instance, our results show for the first time the evolution of systematic and lineage specific structures in a non-human primate that are similar to what is found in the cultural evolution of languages.

 

Vendredi 28 novembre 2014 - 10h30
La SFR Sciences du Cerveau et de la Cognition organise une conférence exceptionnelle à St Charles Amphi Sciences Naturelles

Eleanor MAGUIRE
(Centre for Developmental Cognitive Neuroscience, University College London)

The hidden hero of spatial navigation and memory – revelations from fMRI

La conférence sera suivie d’un apéritif déjeunatoire

 

 

Vendredi 12 Décembre - 11h-12h
(Salle des Voûtes, Féd3C, Centre St Charles, Marseille)

Kumiko FUKUMURA

Audience design during referential communication /(the production of pronouns)

When referring, the same entity can be described with different degree of specificity. A horse can be described with a basic-level description like "horse", a more specific, subordinate-level description like "stallion" (Brennan & Clark, 1996 ; Levelt, 1989) or semantically reduced pronouns such as "he" or "it" (Ariel, 1990 ; Gundel, Hedberg, &
Zacharski, 1993). How do speakers decide which referring expression to use ? For successful reference, the intended referent must be easily identifiable to the addressee (Grice, 1975), so speakers may choose referring expressions to help the addressee’s comprehension or "audience design" (Clark & Murphy, 1982). But the extent to which audience design constrains their referential choice has remained controversial, as many
studies have shown that speakers can be "egocentric" during referential
communication (e.g., Bard & Aylett, 2005 ; Horton & Keysar, 1996 ; Jucks et al., 2008 ; Rossnagel, 2004). In this talk, I will discuss a series of studies that examined the audience design hypothesis for the use of pronouns.

http://www.strath.ac.uk/humanities/courses/psychology/staff/fukumurakumikodr/

 

 

Vendredi 23 Janvier - 10h
(Salle des Voûtes, Fed3C, St Charles, Marseille)

HDR, Laurence CASINI
(LNC, Marseille)

Une horloge dans le cerveau ? Faits, modèles et perspectives

Notre capacité à percevoir le temps qui passe s’étend sur une dizaine d’ordres de grandeur, depuis quelques dizaines de millisecondes à plusieurs années, mais nous savons que les processus permettant de mesurer le temps sont différents selon la gamme de durées concernée. Je me suis particulièrement intéressée aux durées allant de quelques centaines de millisecondes à quelques dizaines de secondes, gamme usuelle de manipulation des informations temporelles. L’idée la plus répandue aujourd’hui est que, pour cette gamme de durées, les intervalles temporels sont estimés grâce à un système spécifiquement dédié à la mesure du temps. Le modèle fonctionnel qui reste prédominant est celui du temps scalaire (ou également dit de l’horloge interne), proposé à l’origine par Gibbon, Church et Meck (1984).
Une première partie de mon travail a eu pour but d’apporter des arguments tant comportementaux que neurobiologiques en faveur de ce modèle. Une deuxième question abordée a été de savoir si les mécanismes et processus mis en jeu sont les mêmes que le traitement temporel soit explicite ou implicite. Enfin, un troisième axe de recherche est consacré aux déficits temporels observés dans deux troubles du développement, la dyslexie et le trouble de l’attention avec ou sans hyperactivité (TDA/H). J’ai essayé d’utiliser le cadre théorique offert par ce modèle pour mieux comprendre les déficits observés.

 

Vendredi 30 Janvier 2015 - 11h-12h
(Salle des Voûtes, Féd3C, Centre St Charles, Marseille)
BLRI

Veronica MONTANI
BLRI, Aix-Marseille Univ

Do visual and attentional factors predict reading skills ?

Visual-attentional abilities have a prominent role in reading. Reading rate is constrained by the number of letters acquired at each fixation, i.e. the visual span, that in turn seems to be mainly determined by the effect of crowding. On the other hand, spatial attention is critically involved in reading process, in particular for the phonological decoding of unfamiliar strings. I will briefly review studies that investigated the role of low-level processing factors in reading and their possible implication in reading disorders. Furthermore, I will present new data that show the distinct contribution of different visual-attentional factors on various reading measures, such as text reading, word naming and eye movements.

 

 

Vendredi 6 Février 2015 - 16h-17h
(Salle des Voûtes, Féd3C, Centre St Charles, Marseille)
BLRI

Mathieu DECLERCK
(BLRI, AMU)

To inhibit or not to inhibit during bilingual language control

One of the mayor topics in the language control literature specifically, and the bilingual literature in general is inhibition, which entails the reduction of non-target language activation and thus interference resolution. In this talk I would discuss the existing evidence for inhibitory control processes at work during language switching, a commonly used task to investigate the underlying mechanism of language control. More specifically, asymmetrical switch costs, n-2 language repetition costs, and reversed language proficiency in mixed language blocks will be discussed in relation to inhibition. Finally, since several models assume little to no implementation of inhibition with highly proficient bilinguals, the role of language proficiency will also be considered.

 

Vendredi 20 Mars - 11h-12h
(Salle des voûtes, Fed3C, Centre St Charles, Marseille)

Louisa BOGAERTS
(University of Ghent)

Linking serial-order learning and language : Evidence from reading (disability)

Hebb repetition learning (HRL), a paradigmatic example of long-term serial-order learning, was hypothesized to provide a laboratory analogue for the processes involved in naturalistic word-form acquisition (Page & Norris, 2008). I’ll discuss experimental evidence showing that verbal HRL (e.g., of the nine-item CV sequence “ri-zo-bu_ni-li-na_sa-ba-du”) indeed results in representations in the mental lexicon that are functionally similar to those of newly learned words (e.g., in this case, the novel "words" rizobu, nilina and sabadu). Furthermore I’ll present the results of a dyslexia study as well as a longitudinal study in early readers, which evidence a contribution of serial-order learning to reading. In the dyslexia study we demonstrated that adults with dyslexia are fundamentally impaired in serial-order learning and show less robust lexicalization of the newly acquired word forms. Dyslexic and control participants do, however, show comparable consolidation, suggesting that the representations that are eventually learned seem to stand the test of time rather well. In the same vein, the results of the developmental study indicate weaker HRL in early readers with poor reading skills. We further observed small but significant correlations between reading performance and the magnitude of HRL. Despite the finding that the Hebb task did not prove to be a useful tool for predicting individual differences in later reading skills, our results do stress the importance of long-term serial-order learning in reading development by showing that HRL explains unique variance in reading performance, above and beyond phonological awareness.

 

Vendredi 27 Mars - 11h-12h
(Salle des Voûtes, fed3C, Centre St Charles, Marseille)

Royce ANDERS
(LPC)

Distributional Reaction Time Data Analysis : Using Process Models with Tractable Complexity

The distributions of reaction time (RT) data are notoriously right-skewed, and classical descriptive statistics such as the mean and standard deviation, which correspond to a Gaussian distributional analysis of the data, provide a mis-matched distributional model. This incongruency can be problematic ; and an appropriate distributional analysis approach can more effectively reveal experiment level differences. In this talk I will review important aspects of distributional RT analysis ; and discuss a range of measurement models with tractable complexity that allow an appropriate quantification of the RT data. There are a number of measurement models that while accounting for the RT distribution, simultaneously model an underlying process leading to the observed response ; and can thus provide a cognitive model for the experimental task. I will highlight my research with such a lesser-known, simple process measurement model, the shifted Wald distribution, which is similar to the Drift Diffusion model, but may be more easily generalizable to a number of experimental paradigms for RT data (due to its simplicity) where the other model is impractical. Such types of models with tractable complexity (easily measurable by data), such as these that model signal accumulation, will be contrasted and compared to models of less-tractable complexity (difficult to measure by data), such as neural network models, that pose a challenge to be truly validated on real data, despite being more informative of a richer underlying process.`

 

ATTENTION !!!!!!! Jour et Horaires !!!!!!!

JEUDI 2 Avril - 10h30-12h
(Salle des Voûtes, Fed3C, Centre St Charles, Marseille)

Jamie Campbell
University of Saskatchewan (Canada)

Cognitive Arithmetic : News from Transfer of Learning

Over the last few years, work in my lab has studied memory for everyday arithmetic facts (e.g., 2 + 4 = 6) through the phenomena of retrieval-induced interference as well as facilitative transfer of learning through generalization of practice. I will review some of this recent transfer work and also talk about new, as yet published findings. The retrieval-induced interference phenomena are challenging because they appear to imply a type of inhibitory mechanism (competitor inhibition below baseline) that no theory of cognitive arithmetic currently explains. The generalization data potentially have important implications for recent claims that adult’s skilled performance of simple addition may be based on fast counting procedures rather than based on fact retrieval from semantic memory. In another application, retrieval-induced interference and generalization phenomena also suggest that strong bilinguals may possess language-specific arithmetic memory networks.

 

Valerie Thompson
(University of Saskatchewan, Canada)

Metacognition and Intuition in a Denominator Neglect Task : Converging Evidence from Individual Differences and Gaze Tracking Analyses

It is a well-established finding that people with high IQ and who are motivated to think analytically perform better on a variety of reasoning tasks than their less able and less motivated counterparts. The usual interpretation of this relationship is that the former group have the capacity and motivation to inhibit appealing intuitive answers and engage the necessary resources to derive a correct one. In this talk, I will present some counter-intuitive evidence to suggest that high-IQ people are more accurate, even when they must respond under time pressure, suggesting that their intuitions, as well as their deliberations, are better than low-IQ reasoners. I will also provide an analysis of gaze patterns that help to elucidate strategies that lead to accurate and confident responses.

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Vendredi 12 Juin

11h-12h

(Salle des voûtes, Fed3C

Centre St Charles, Marseille)


Mieke DONK
(Department of Cognitive Psychology, VU University Amsterdam, The Netherlands)

On the time course of oculomotor selection behavior

We are continuously monitoring our visual environment, both by covertly orienting our attention from one to another location and by overtly making eye movements to sequentially bring different parts of the environment into foveal vision. How do we choose the next location of selection over and over again ? The present contribution aims to provide an overview of some research explicitly concerned with the question how the control of eye movements varies with the timing of the oculomotor response. The findings of several studies will be reported demonstrating the time-dependent influence of salience, task-goals, feature priming, and memory on oculomotor selection behavior. The results and implications will be discussed in relation to current views on visual selection.

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Vendredi 19Juin - 11h-12h
(Salle des Voûtes, Fed3C, Centre St Charles, Marseille)

Valérie CAMOS
(Université de Fribourg - Switzerland)

Functioning and Development of Working Memory through the Time-Based Resource-Sharing Model

This talk will present the Time-Based Resource-Sharing model of working memory. In a multi-level cognitive architecture, a central system, conceived as a self-regulated executive loop involving an episodic buffer and a production system, integrates information from peripheral domain-specific buffers and long-term memory. The executive loop is responsible for constructing working memory representations, for maintaining these representations in the face of decay and interference, and for goal-directed processing by triggering executive functions that modify the content of these representations. Apart from a phonological loop able to maintain a limited amount of verbal information through verbal rehearsal, peripheral buffers are conceived of as passive sensory memories with no specific mechanisms of maintenance. Assuming a sequential functioning of the executive loop and the temporal decay of working memory representations, the theory makes a series of predictions about the time-related effect of processing on concurrent maintenance and the postponement of processing by maintenance activities. This talk will review empirical findings in young adults supporting these predictions as well as studies in children, which shed light on factors of working memory development.

 

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THèSES

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Jeudi 11 Décembre

14h

( Salle des Voûtes, Fed3C

 Centre St Charles, Marseille)

Laure POURCIN


J’ai le plaisir de vous inviter à la soutenance de ma thèse intitulée :

"Évaluation cognitive de la lecture chez le collégien : Élaboration d’un outil d’évaluation diagnostique"

Le jury sera composé de :

DEMONT Elisabeth, Professeure, Université de Strasbourg (Rapporteur)
LÉTÉ Bernard, Professeur, Université de Lyon 2 (Rapporteur)
DUNCAN Lynne, Lecturer, University of Dundee (Examinateur)
ZIEGLER Johannes, Directeur de recherche, CNRS (Examinateur)
COLÉ Pascale, Professeure, Aix-Marseille Université (Directeur)
SPRENGER-CHAROLLES Liliane, Directeur de recherche (émérite), CNRS (Directeur)

Résumé : Cette thèse est centrée sur l’évaluation des capacités de lecture et de celles reliées à la lecture des collégiens normo-lecteurs français. Le premier objectif est d’identifier les processus cognitifs engagés dans la compréhension écrite. Dans les premiers grades (6ème et 5ème), les capacités de compréhension écrite sont surtout expliquées par celles de compréhension orale, de conscience morphologique et de lecture de mots irréguliers, mais pas par la lecture de pseudomots, quelle que soit la mesure (précision ou temps). Ce dernier résultat se retrouve dans les grades supérieurs (4ème et 3ème) dans lesquels la lecture de mots irréguliers, toujours quelle que soit la mesure, n’a plus d’incidence sur la compréhension écrite. Le second objectif est d’élaborer un outil d’évaluation diagnostique des capacités d’identification des mots écrits, et des capacités reliées, chez les collégiens (6ème à 3ème). L’examen des capacités d’identifications des mots écrits montre que les effets de régularité et de lexicalité sont significatifs, quelle que soit la mesure, et le niveau scolaire. Les effets de longueur varient selon la lexicalité : quel que soit le niveau scolaire, les pseudomots longs sont lus moins précisément et moins rapidement que les courts alors que les mots irréguliers longs ne sont jamais pénalisés. Le niveau de lecture (mesuré à l’aide d’un test Français de référence) est déterminé surtout par les capacités de lecture de pseudomots, et également par celles de conscience phonémique mais uniquement lorsque les temps sont pris en compte. La construction cohérente de l’outil est vérifiée à l’aide d’une méthode statistique particulière : une classification hiérarchique de variables. L’ensemble des résultats souligne l’importance de considérer pour toutes évaluations les temps de traitement en plus de la précision.

Mots clés : compréhension écrite, compréhension orale, identification de mots écrits, capacités reliées à la lecture, outil d’évaluation de la lecture

Abstract : The aim of this thesis was to evaluate the reading and reading-related skills of French middle school students (Grades 6 to 9). The first objective was to identify the cognitive processes involved in reading comprehension at the middle school level. In the first grades (Grades 6 and 7), the results show that reading comprehension skills are largely predicted by listening comprehension, morphological awareness, and irregular word reading, but not pseudoword reading skills, whatever the measure (accuracy or time). This latter result is found in the higher grades (Grades 8 and 9) in which irregular word reading has no impact on reading comprehension, again regardless of the measure. The second objective was to develop a diagnostic evaluation tool for word-level reading and reading-related skills in middle school students. The examination of word-level reading skills at middle school showed significant effects of both regularity and lexicality, whatever the measure and independently of grade. The effect of length depends on lexicality : long pseudowords are read less accurately and more slowly than short ones, whereas long irregular words are read as well as short ones. Reading level (assessed by a French “gold standard” test) is mainly predicted by pseudoword reading skills, and also by phonemic awareness, for response times. The consistent structure (validity) of the tool is verified using a new statistical method : hierarchical classification of variables. The overall results underline the importance of considering response times in addition to accuracy in all assessments.

Keywords : reading comprehension, listening comprehension, word-level reading, reading-related skills, reading evaluation tool

La soutenance sera suivie d’un pot auquel vous êtes cordialement invités.

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Lundi 15 Décembre

14h30

(Salle des voûtes, Fed3C
Centre St Charles, Marseille)

Julien TAILLAN


Je soutiendrai ma thèse intitulée :

"Vieillissement et variations stratégiques : Études des processus impliqués dans la sélection stratégique et leur évolution avec l’âge."

 

Membres du jury :
ISINGRINI Michel, Professeur, Université de Tours (Rapporteur)
THOMAS Elizabeth, Maître de conférences, Université de Bourgogne (Rapporteur)
ALESCIO-LAUTIER Béatrice, Directrice de Recherche, Université Aix-Marseille (Examinateur)
LEMAIRE Patrick, Professeur, Université Aix-Marseille (Directeur)


Résumé :
Les chercheurs en psychologie ont montré que nous utilisons différentes stratégies pour accomplir différentes tâches cognitives. Une stratégie est une procédure ou un ensemble de procédures permettant aux participants d’atteindre un but cognitif. La question importante est alors de savoir comment nous choisissons une stratégie parmi toutes les stratégies disponibles.
Pour améliorer nos connaissances sur ce phénomène, l’objectif général de cette thèse était d’étudier les processus impliqués dans la sélection stratégique, ainsi que leur évolution au cours du vieillissement.
Pour cela, nous avons adopté une double approche neuroscientifique et cognitive. Les données rapportées dans nos études IRMf indiquent qu’un réseau cérébral spécifique serait associé à la sélection stratégique.
Ce réseau comprend notamment des régions préfrontales connues pour être recrutées dans des tâches impliquant les fonctions exécutives. Ainsi nos données suggèrent que, contrairement à ce que postulent les modèles théoriques, les fonctions exécutives pourraient être impliquées dans la sélection stratégique. L’absence d’activation dans ces régions chez les participants âgés pourrait nous aider à expliquer pourquoi la capacité à choisir la meilleure stratégie diminue avec l’âge. De manière intéressante, nous montrons aussi que les participants peuvent utiliser différents processus de sélection stratégique en fonction de la difficulté des problèmes. Enfin, dans la dernière partie, nous discutons des implications de nos résultats au niveau des modèles de la sélection stratégique, ainsi qu’au
niveau du vieillissement cognitif.

Mots-clés :
Sélection stratégique, Vieillissement, IRMf, ERP, Arithmétique

Abstract :
Researchers in psychology have shown that we use several strategies to accomplish cognitive tasks. A strategy is a procedure or a set of procedures for achieving a higher level goal or task. One of the crucial issues concerns how we choose a strategy among several available strategies to solve each problem. To further our understanding of strategy selection, the overall objective of this thesis was to investigate processes involved in strategy selection, and their evolution with aging. To achieve this goal, we adopted both neuroscience and cognitive approach. Data reported in our fMRI studies indicate that a specific network was associated with strategy selection. This particular network includes prefrontal regions known to be engaged in tasks involving executive functions. Thus, our data suggest that, contrary to the assumptions of theoretical models, executive functions may be involved in the strategy selection. The lack of activation in these regions in older adults may help us to understand why the ability to choose the better strategy decreases during aging. Interestingly, we also show that participants can use different strategy selection processes based on the difficulty of problems.Finally, in the last section, we discuss the implications of our results for theoretical models of strategy selection, and for cognitive aging.

Keywords :
Strategy selection, Aging, fMRI, ERP, Arithmetic

Vous êtes chaleureusement conviés au pot qui suivra.

taillanjulien@hotmail.fr

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Jeudi 23 Avril 2015 

14h
 

(Salle des voûtes
Centre Saint Charles
3, Place Victor Hugo
13331 Marseille)

Delphine MASSENDARI

 

 

Je soutiendrai ma thèse intitulée :

« La programmation des saccades oculaires chez l’homme : rôle et décours temporel des traitements visuels élémentaires »


 Composition du jury :

Dr. Muriel BOUCART ; LNFP, CNRS, Université de Lille 3 ; Rapporteur
Dr. Denis PELISSON ; ImpAct, INSERM, CNRS, Univesité Claude Bernard, Lyon 1 ; Rapporteur
Dr. Simon THORPE ; Cerco, CNRS, Université de Toulouse 3 ; Examinateur
Pr. Robin WALKER ; Departement of Psycholoy, Royal Holloway University of London ; Examinateur
Dr. Jean BLOUIN ; LNC, CNRS, Aix-Marseille Université ; Examinateur
Dr. Françoise VITU ; LPC, CNRS, Aix-Marseille Université ; Directrice de thèse

Dr. Christophe TANDONNET ; Faculté de Psychologie et Sciences de l’éducation, Université de Génève ; Co-Directeur de thèse


Résumé :

Notre environnement visuel est riche en lumière, couleurs, traits, textures et formes. Pour appréhender cette richesse en dépit de la mauvaise acuité de notre vision périphérique, nous déplaçons nos yeux tous les quarts de seconde à l’aide de mouvements très rapides appelés saccades. Une telle vision dite active a fait l’objet de multiples recherches, mais les interactions entre les systèmes visuel et oculomoteur ne sont pas clairement établies. Cette thèse vise à préciser ces interactions en étudiant si les délais temporels associés au traitement d’informations visuelles de plus en plus élaborées contraignent où et quand nos yeux bougent. Nous nous sommes focalisés sur trois traitements visuels élémentaires, dont les substrats neuronaux, bien établis, prédisent une influence ordonnée sur la programmation des saccades au niveau du colliculus supérieur. Trois séries d’études comportementales menées chez l’homme et utilisant des paradigmes novateurs ont été réalisées. Elles nous ont permis de mettre en évidence que le traitement des contrastes d’orientation, tout comme le traitement plus précoce des contrastes de luminance sont intégrés par le système saccadique. En effet, un stimulus (distracteur) différant d’un fond texturé par sa luminance ou son orientation dévie le regard de sa cible dans la même mesure, et ce, quelle que soit la latence des saccades. Néanmoins, le contraste de luminance conserve un rôle prédominant. Premièrement, il conduit au déclenchement plus précoce des saccades en comparaison avec le contraste d’orientation. Deuxièmement, dès lors qu’il entre en compétition avec des informations plus élaborées comme le contour, il suffit à déterminer la métrique des saccades. Ainsi, en accord avec l’architecture des systèmes visuel et oculomoteur, les traitements visuels influencent la programmation des saccades de manière ordonnée. Les modèles de production des saccades, qui, pour la plupart, considèrent indifféremment les influences exogènes, bénéficieront de prendre en compte cette architecture et les délais incompressibles associés au traitement des différentes informations visuelles.

Mots-clés : Saccades, Contrastes de luminance, Contrastes d’orientation, Contour, Effet global, Décours temporel, Saillance, Choix forcé

 

Abstract :

Our environment is rich in light, color, features, textures, and shapes. To extract this information despite the low acuity of our peripheral vision, we move our eyes four times per second with rapid eye movements called saccades. This so-called active vision has been studied extensively, but the interactions between the visual and oculomotor systems have not been fully characterized yet. This thesis aims to clarify these interactions by investigating whether the delays in processing visual information of increasing complexity determine where and when our eyes move. The present work focuses on three types of basic visual processing for which the neural substrates are well established and predict a specific order in the programming of saccades at the level of the superior colliculus. We conducted three series of behavioral studies with human participants using novel experimental paradigms. These studies showed that orientation-contrast processing as well as early luminance-contrast processing are integrated in the saccadic system to the same extent. When aiming for a target stimulus, the eyes deviate toward a distractor stimulus in equal measure, irrespective of whether the distractor differed in luminance or orientation from a texture background and irrespective of saccade latency. However, the role of luminance contrast remains dominant. Firstly, luminance contrast triggers faster saccades than orientation contrast. Secondly, when luminance contrast competes with more complex information such as contour, solely luminance contrast determines saccade metrics. Therefore, visual processes influence saccade programming in a specific order that is consistent with the architecture of the visual and oculomotor systems. Models of saccade generation, which rarely distinguish between various exogenous influences, would benefit from considering this architecture and the minimum processing delays associated with various types of visual information.


Keywords : Saccades, Luminance contrast, Orientation contrast, Contour, Global effet, Time course, Saliency, Forced choice

 

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