Visual motion processing and human tracking behavior

The accurate visual tracking of a moving object is a human fundamental skill that allows to reduce the relative slip and instability of the object's image on the retina, thus granting a stable, high-quality vision. In order to optimize tracking performance across time, a quick estimate of the object's global motion properties needs to be fed to the oculomotor system and dynamically updated. Concurrently, performance can be greatly improved in terms of latency and accuracy by taking into account predictive cues, especially under variable conditions of visibility and in presence of ambiguous retinal information. Here, we review several recent studies focusing on the integration of retinal and extra-retinal information for the control of human smooth pursuit.By dynamically probing the tracking performance with well established paradigms in the visual perception and oculomotor literature we provide the basis to test theoretical hypotheses within the framework of dynamic probabilistic inference. We will in particular present the applications of these results in light of state-of-the-art computer vision algorithms

Early Visual Saliency Based on Isolated Optimal Features

International audienc

A Model of Optimal Oculomotor Strategies in Reading for Normal and Damaged Visual Fields

ISBN : 978-2-9532965-0-1We present an ideal observer analysis of single word reading in normal readers and central scotoma patients. Using this technique we are able to predict the spatio-temporal pattern of saccades in terms of pixels. This enables us to contrast theories that are impossible to compare using the traditional letter-slot approaches to modelling reading

A Dynamic Approach to the Thermodynamics of Superdiffusion

We address the problem of relating thermodynamics to mechanics in the case of microscopic dynamics without a finite time scale. The solution is obtained by expressing the Tsallis entropic index q as a function of the Levy index alpha, and using dynamical rather than probabilistic arguments.Comment: 4 pages, new revised version resubmitted to Phys. Rev. Let

Decision making in the human saccadic eye movement system: effects of expectancy, conflict and motivation

The aim of this thesis is to investigate the isolated and jointed influence of contextual factors, such as expectancy, conflict and motivation, on the latency distribution of saccades. The underlying hypothesis is that the analysis of the orienting eye movements recorded from human volunteers during simple saccadic tasks might provide a good insight into the decision-making mechanisms of our brain. The main focus is on a manipulation, to which we refer as the probability-bias manipulation, designed to study the effects, on the generation of saccades, of spatiotemporal uncertainty regarding the location of the saccade target. Uncertainty is likely to affect the expectancy for a given sensorimotor event and this is reasonably a crucial determinant for the decision-making process leading to a saccade. The first central question addressed in chapter 3 is whether and how probabilistic information about the location of the target is used (consciously or unconsciously) by the oculomotor system under different task demands. The probability-bias manipulation can also be seen as a particular instantiation of sequence-related effects, or, in other terms, of those effects resulting from the history of the past trials. Therefore, the effect of the main manipulation might interact with the local trial-sequence structure, i.e. the specific trials preceding the current one. In chapter 4 we present some results about this type of effects. The use of probabilistic information, and the corresponding adaptation of behaviour to the stimulus statistics, can be compared to the theoretical limits due to the finite size of the available sample of data. These limits can be defined in a mathematically precise form on the basis of the theory of statistical inference and of the Bayesian rule. In chapter 5 we address the issue of how efficiently, with respect to the theoretical limits, the distribution of saccadic latency adapts to the probability-bias manipulation. The idea about this type of analysis came from several interesting discussions with professor William Bialek, at the University of Princeton, during a short-term visit which was part of my PhD programme. The interaction of the probability-bias manipulation with the graded involvement of voluntary control in the generation of saccades is also a main focus of this thesis. For this reason we tested our subjects with a set of paradigms demanding a different degree of voluntary commitment. In chapter 6, we analyse in particular the interaction of the probability bias with a decisional conflict, between the tendency to orient gaze to a visual onset and the required inhibition of the saccade. Finally, if we assume that the mechanisms of sensorimotor integration are capable to efficiently use the probabilistic information about the stimuli to optimise the behavioural performance, an interesting possibility is that such capability would maximally emerge when the target stimuli are associated to a strong motivational valence. This issue is examined at several points in the text of this thesis, and is discussed with particular attention in chapters 3 and 5. In chapter 7 we analyse the effect exerted by a manipulation of the valence per se, dissociating it from the probability bias manipulation. In other terms, we analyse the influence that the motivation to orient to the saccadic goal has on simple stimulus-elicited saccades

Active Vision and Probabilistic Inference

This manuscript presents a synthesis of my scientific work, in order to obtain the Habilitation`a Diriger des Recherches (HDR) diploma. It is an opportunity, for me, to take stock of myscientific evolution so far, as well as to reflect about the collaborative research projects that Iwish to set up and coordinate over the next few years. Within these projects, I hope to be ableto supervise and mentor many talented and motivated students and young researchers.The first part of the manuscript (introduction and chapters 1 to 3) summarizes my researchfrom 2009 to 2017 (with references to some previous research work), i. e. from the beginning ofmy activity as a permanent researcher at the CNRS.The second part (Chapters 4 and 5) presents the perspectives of my research in the future,either in the smooth continuity with the ongoing projects, or with regard to the novelties andoriginal ideas that I hope to introduce in the years to come. In the Conclusion (Chapter 6)I allow myself some personal considerations, to sketch a brief state of the art of my researchtheme and express a point of view on its evolution.Finally, in the Annexes, I present my curriculum vitae, a complete list of scientific publicationsand communications, the list of collaborative projects funded by national or international grants,as well as the list of students supervised or co-supervised during the past years.Ce manuscrit presente une synthese de mon projet scientifique afin d’obtenir le diplomed’Habilitation a Diriger des Recherches (HDR). Il est l’occasion de faire le point sur monparcours scientifique, ainsi que de reflechir aux projets de recherche collaborative que je souhaitemettre en place et coordonner au cours des prochaines annees. Au sein de ces projets, j’esperepouvoir encadrer nombreux etudiants et jeunes chercheurs talentueux et motives.La premiere partie du manuscrit (introduction et chapitres 1 a 3) resume mon parcours derecherche de 2009 `a 2017 (avec des references aux travaux de recherche antecedents), c’est a direa partir du debut de mon activite de chercheur statutaire au sein du CNRS.La deuxieme partie (chapitres 4 et 5) presente les perspectives de mes recherches dans lefutur, aussi bien dans la continuite proche des projets en cours, que a l’egard des nouveauteset des idees originales que j’espere introduire dans les annees `a suivre. Dans la Conclusion(chapitre 6) je me permets quelques considerations personnelles, un petit etat de lieu de monsujet de recherche et mon point de vue sur son evolution.Pour finir, en annexe je presente mon curriculum vitae, une liste complete de publications etcommunications scientifiques, la liste des projets collaboratifs finances par grants nationaux ouinternationaux, ainsi que la liste des etudiants encadres ou co-encadres pendant mon parcoursde recherche

Active Vision and Probabilistic Inference

This manuscript presents a synthesis of my scientific work, in order to obtain the Habilitation`a Diriger des Recherches (HDR) diploma. It is an opportunity, for me, to take stock of myscientific evolution so far, as well as to reflect about the collaborative research projects that Iwish to set up and coordinate over the next few years. Within these projects, I hope to be ableto supervise and mentor many talented and motivated students and young researchers.The first part of the manuscript (introduction and chapters 1 to 3) summarizes my researchfrom 2009 to 2017 (with references to some previous research work), i. e. from the beginning ofmy activity as a permanent researcher at the CNRS.The second part (Chapters 4 and 5) presents the perspectives of my research in the future,either in the smooth continuity with the ongoing projects, or with regard to the novelties andoriginal ideas that I hope to introduce in the years to come. In the Conclusion (Chapter 6)I allow myself some personal considerations, to sketch a brief state of the art of my researchtheme and express a point of view on its evolution.Finally, in the Annexes, I present my curriculum vitae, a complete list of scientific publicationsand communications, the list of collaborative projects funded by national or international grants,as well as the list of students supervised or co-supervised during the past years.Ce manuscrit presente une synthese de mon projet scientifique afin d’obtenir le diplomed’Habilitation a Diriger des Recherches (HDR). Il est l’occasion de faire le point sur monparcours scientifique, ainsi que de reflechir aux projets de recherche collaborative que je souhaitemettre en place et coordonner au cours des prochaines annees. Au sein de ces projets, j’esperepouvoir encadrer nombreux etudiants et jeunes chercheurs talentueux et motives.La premiere partie du manuscrit (introduction et chapitres 1 a 3) resume mon parcours derecherche de 2009 `a 2017 (avec des references aux travaux de recherche antecedents), c’est a direa partir du debut de mon activite de chercheur statutaire au sein du CNRS.La deuxieme partie (chapitres 4 et 5) presente les perspectives de mes recherches dans lefutur, aussi bien dans la continuite proche des projets en cours, que a l’egard des nouveauteset des idees originales que j’espere introduire dans les annees `a suivre. Dans la Conclusion(chapitre 6) je me permets quelques considerations personnelles, un petit etat de lieu de monsujet de recherche et mon point de vue sur son evolution.Pour finir, en annexe je presente mon curriculum vitae, une liste complete de publications etcommunications scientifiques, la liste des projets collaboratifs finances par grants nationaux ouinternationaux, ainsi que la liste des etudiants encadres ou co-encadres pendant mon parcoursde recherche

Active Vision and Probabilistic Inference

This manuscript presents a synthesis of my scientific work, in order to obtain the Habilitation`a Diriger des Recherches (HDR) diploma. It is an opportunity, for me, to take stock of myscientific evolution so far, as well as to reflect about the collaborative research projects that Iwish to set up and coordinate over the next few years. Within these projects, I hope to be ableto supervise and mentor many talented and motivated students and young researchers.The first part of the manuscript (introduction and chapters 1 to 3) summarizes my researchfrom 2009 to 2017 (with references to some previous research work), i. e. from the beginning ofmy activity as a permanent researcher at the CNRS.The second part (Chapters 4 and 5) presents the perspectives of my research in the future,either in the smooth continuity with the ongoing projects, or with regard to the novelties andoriginal ideas that I hope to introduce in the years to come. In the Conclusion (Chapter 6)I allow myself some personal considerations, to sketch a brief state of the art of my researchtheme and express a point of view on its evolution.Finally, in the Annexes, I present my curriculum vitae, a complete list of scientific publicationsand communications, the list of collaborative projects funded by national or international grants,as well as the list of students supervised or co-supervised during the past years.Ce manuscrit presente une synthese de mon projet scientifique afin d’obtenir le diplomed’Habilitation a Diriger des Recherches (HDR). Il est l’occasion de faire le point sur monparcours scientifique, ainsi que de reflechir aux projets de recherche collaborative que je souhaitemettre en place et coordonner au cours des prochaines annees. Au sein de ces projets, j’esperepouvoir encadrer nombreux etudiants et jeunes chercheurs talentueux et motives.La premiere partie du manuscrit (introduction et chapitres 1 a 3) resume mon parcours derecherche de 2009 `a 2017 (avec des references aux travaux de recherche antecedents), c’est a direa partir du debut de mon activite de chercheur statutaire au sein du CNRS.La deuxieme partie (chapitres 4 et 5) presente les perspectives de mes recherches dans lefutur, aussi bien dans la continuite proche des projets en cours, que a l’egard des nouveauteset des idees originales que j’espere introduire dans les annees `a suivre. Dans la Conclusion(chapitre 6) je me permets quelques considerations personnelles, un petit etat de lieu de monsujet de recherche et mon point de vue sur son evolution.Pour finir, en annexe je presente mon curriculum vitae, une liste complete de publications etcommunications scientifiques, la liste des projets collaboratifs finances par grants nationaux ouinternationaux, ainsi que la liste des etudiants encadres ou co-encadres pendant mon parcoursde recherche

Active Vision and Probabilistic Inference

This manuscript presents a synthesis of my scientific work, in order to obtain the Habilitation`a Diriger des Recherches (HDR) diploma. It is an opportunity, for me, to take stock of myscientific evolution so far, as well as to reflect about the collaborative research projects that Iwish to set up and coordinate over the next few years. Within these projects, I hope to be ableto supervise and mentor many talented and motivated students and young researchers.The first part of the manuscript (introduction and chapters 1 to 3) summarizes my researchfrom 2009 to 2017 (with references to some previous research work), i. e. from the beginning ofmy activity as a permanent researcher at the CNRS.The second part (Chapters 4 and 5) presents the perspectives of my research in the future,either in the smooth continuity with the ongoing projects, or with regard to the novelties andoriginal ideas that I hope to introduce in the years to come. In the Conclusion (Chapter 6)I allow myself some personal considerations, to sketch a brief state of the art of my researchtheme and express a point of view on its evolution.Finally, in the Annexes, I present my curriculum vitae, a complete list of scientific publicationsand communications, the list of collaborative projects funded by national or international grants,as well as the list of students supervised or co-supervised during the past years.Ce manuscrit presente une synthese de mon projet scientifique afin d’obtenir le diplomed’Habilitation a Diriger des Recherches (HDR). Il est l’occasion de faire le point sur monparcours scientifique, ainsi que de reflechir aux projets de recherche collaborative que je souhaitemettre en place et coordonner au cours des prochaines annees. Au sein de ces projets, j’esperepouvoir encadrer nombreux etudiants et jeunes chercheurs talentueux et motives.La premiere partie du manuscrit (introduction et chapitres 1 a 3) resume mon parcours derecherche de 2009 `a 2017 (avec des references aux travaux de recherche antecedents), c’est a direa partir du debut de mon activite de chercheur statutaire au sein du CNRS.La deuxieme partie (chapitres 4 et 5) presente les perspectives de mes recherches dans lefutur, aussi bien dans la continuite proche des projets en cours, que a l’egard des nouveauteset des idees originales que j’espere introduire dans les annees `a suivre. Dans la Conclusion(chapitre 6) je me permets quelques considerations personnelles, un petit etat de lieu de monsujet de recherche et mon point de vue sur son evolution.Pour finir, en annexe je presente mon curriculum vitae, une liste complete de publications etcommunications scientifiques, la liste des projets collaboratifs finances par grants nationaux ouinternationaux, ainsi que la liste des etudiants encadres ou co-encadres pendant mon parcoursde recherche

Spatiotemporal dynamics of visual attention during saccade preparation: independence and coupling between attention and movement

During the preparation of a saccadic eye movement, a visual stimulus is more efficiently processed when it is spatially coincident with the saccadic target as compared to when the visual and the saccadic targets are displayed at different locations. We studied the coupling between visual selective attention and saccadic preparation by measuring orientation acuity of human subjects at different locations relative to the saccadic target and at different delays relative to the saccade cue onset. First, we generalized previous results (E. Castet, S. Jeanjean, A. Montagnini, D. Laugier, & G. S