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Traitements Probabilistes Implicites De La Perception Ambigüe En Vision Humaine

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Traitements Probabilistes Implicites De La Perception Ambigüe En Vision Humaine Thèse de Doctorat de l’université Paris Descartes ED 261 : Cognition, Comportement, Conduites Humaines TRAITEMENTS PROBABILISTES IMPLICITES DE LA PERCEPTION AMBIGÜE EN VISION HUMAINE Adrien Chopin Pascal Mamassian – Directeur de thèse Jury Pr Philippe Schyns – Rapporteur Dr Jean Lorenceau – Rapporteur Pr Daphné Bavelier - Examinateur Pr Patrick Cavanagh – Examinateur Dr Jean-Michel Hupé – Membre Invité Laboratoire de Psychologie de la Perception Université Paris Descartes, Sorbonne Paris Cité et CNRS UMR 8158 v vi VERSION CORRIGEE ET AVANCEE - NON-OFFICIELLE (UNOFFICIAL CORRECTED AND ADVANCED VERSION) vii Mots-clés : perception visuelle, bistabilité, rivalité binoculaire, adaptation, attention, apprentissage perceptif, vision stéréoscopique, utilité. Résumé La bistabilité est une surprenante alternance de l’apparence d’un stimulus entre deux interprétations de ce stimulus. Elle a lieu lorsqu’une stimulation physique est très ambigüe, comme lorsque l’on présente une image dans un œil très différente de l’image de l’autre œil (rivalité binoculaire). La bistabilité implique de (1) décider que le stimulus est bistable ; (2) sélectionner le premier percept ; (3) supprimer l’autre percept ; (4) décider quand alterner. Tandis que les deux dernières étapes sont très étudiées, les deux premières étapes restent encore mal connues. Ici, nous approfondissons les connaissances sur les mécanismes qui décident la rivalité plutôt que la fusion (étude 4), sur le choix du premier percept (études 1 à 5) et sur la dynamique bistable (étude 1 et 3). Notamment, la littérature actuelle favorise une explication bas-niveau de la rivalité binoculaire, c’est-à-dire ayant lieu dès les premières étapes de traitement cognitif, avant tout traitement complexe. Le but principal de cette thèse est de clarifier l’influence potentielle sur la rivalité de traitements probabilistes et donc plus complexes. J’ai étudié (1) l’influence de l’utilité d’une interprétation sur la bistabilité ; (2) la manière de changer les préférences bistables ; (3) la spécificité du ou des premiers percepts ; (4) l’influence d’illusions d’orientations sur la stéréo-fusion et la rivalité ; (5) l’influence du passé sur le percept bistable, sous la forme de prédictions du système. J’ai trouvé : (1) qu’une interprétation utile est perçue plus souvent sur le premier percept d’un épisode de rivalité binoculaire. Cette influence est implicite, non-attentionnelle et implique des calculs probabilistes sur l’utilité d’un percept. (2) que l’utilité peut modifier les préférences en rivalité de transparence de mouvement et que ces préférences ont donc pour rôle de favoriser la réussite à une tâche. (3) que le premier percept de la rivalité binoculaire n’est pas le seul à être différent des autres et que le contrôle volontaire est plus fort au début d’un épisode bistable pour le percept non-favorisé. (4) que l’étape de contraste illusoire entre orientations occupe une position hiérarchique plus basse que les étapes de vision stéréoscopique et de rivalité. (5) une forte corrélation positive entre le passé visuel ancien et l’orientation perçue en rivalité binoculaire. Nous expliquons ce résultat par un modèle d’adaptation prédictive selon lequel le système visuel prédit le prochain percept tel que la distribution récente des orientations corresponde à une distribution plus ancienne. Ici encore, des calculs probabilistes sont impliqués. En résumé, ce travail démontre principalement l’existence de traitements probabilistes en perception ambigüe, par l’intermédiaire d’un calcul d’utilité et de prédictions dans l’adaptation. viii ix Keywords: visual perception, bistability, binocular rivalry, adaptation, attention, perceptual learning, stereopsis, usefulness. Abstract Bistability is a surprising alternation of the appearance of a stimulus between two interpretations of that stimulus. It occurs when a physical stimulation is ambiguous, e.g. when very different images are displayed to each eye. Bistability involves (1) a decision that the stimulus has to be bistable; (2) a selection of the first percept; (3) a suppression of the other percept; (4) a decision of when reversing the percepts. While the two first steps have been widely studied, a lot remain to be discovered on the two last steps. Here, we focus on the mechanisms that decide for rivalry rather than fusion (study 4), that choose the first percept (studies 1 to 5) and on bistable dynamics (studies 1 and 3). Moreover, the literature tends to support a low-level explanation of binocular rivalry, i.e. occurring as soon as the first steps of cognitive computation, before any complex calculation. One of the main goals of this work is to clarify the potential influence of probabilistic processes that may be more complex. I studied (1) the influence of one interpretation’s usefulness on bistability; (2) the way of changing bistable preferences; (3) the specificity of the first percepts; (4) the influence of orientation illusion on stereo-fusion and rivalry; (5) the influence of past stimuli on the bistable percept through predictions. I found that: (1) One useful interpretation is perceived more often on the first percept of a bistable episode of binocular rivalry. This influence is implicit, not attentional and implies probabilistic computations about percept usefulness. (2) Usefulness can change preferences for motion transparency depth rivalry: those preferences are therefore aimed at increasing the observer’s success to a task. (3) The first percept of binocular rivalry is not the only one to be different from the others and that voluntary control is more effective at the beginning of a bistable episode for the not preferred percept. (4) The step of illusory contrast between orientations occurs lower in the hierarchy relative to stereopsis and binocular rivalry. (5) A strong positive correlation between the remote visual past and the current perceived orientation in binocular rivalry. We explained this finding with a model of predictive adaptation according to which the visual system predicts the next percept following the following rule: the recent distribution of orientations has to match the remote past distribution. Here again, probabilistic computations are involved. To summarize, this work mainly uncovers the existence of probabilistic computations in ambiguous perception through usefulness computation and predictions in adaptation. x xi Remerciements Cavalier Maurits Cornelis Escher 1945 J’ai remarqué que la plupart des gens abordaient la lecture d’une thèse en commençant par cette page de remerciements, comme si elle en était le couronnement, l’essence. Je ne connais pas la raison de ce phénomène, mais je me suis surpris à faire la même chose. Très souvent aussi, la lecture de la thèse s’achève avec cette page. La première version des remerciements était une liste infinie de « merci » pour toutes les personnes appréciables et susceptibles de désirer être remerciées. Finalement, plutôt que de décevoir beaucoup les quelques personnes oubliées, j’ai décidé de décevoir un peu tout le monde mais également. Je ne remercie donc presque personne par son nom mais si vous en êtes vexés, c’est que vous faites définitivement partie des personnes que je remercie. Je fais quelques exceptions pour les personnes qui m’ont aidé académiquement et que je n’ai pas encore remerciées dans les articles. Par exemple, je remercie infiniment mon directeur de thèse, Pascal. Il a su m’orienter avec sagesse et créativité à travers mes travaux et canaliser mon énergie pour que j’atteigne les objectifs que je m’étais fixés. Il a pu m’accorder le temps dont j’avais besoin malgré un emploi du temps continuellement titanesque. Je lui suis reconnaissant de m’avoir guidé à travers le monde de la recherche en me permettant de diffuser largement mes travaux jusqu’en Floride. Je remercie les membres de mon jury de me faire l’honneur de considérer mon travail, tout particulièrement les rapporteurs. Je sais que certains membres ont dû aménager sévèrement leur emploi du temps afin d’être présents : merci ! xii Un grand merci aux étudiants et chercheurs du laboratoire de Psychologie de la Perception pour l’excellente ambiance et l’émulation intellectuelle. Je pense notamment à Simon Barthelmé qui m’a apporté le terreau de certaines recherches (comme le concept du paradoxe du joueur). Je remercie spécialement Marie de Montalembert pour son soutien pendant la dernière ligne. Je suis reconnaissant à toutes les personnes qui ont eu la gentillesse de me donner leur avis sur mon travail et de m’aider à l’améliorer. Et merci aux relecteurs, Jennifer Lalanne, Marie de Montalembert, Marina Zannoli, Anissa Aliyahia, Mohammed Ghezal, Nathalie Genty, Hadwig Chopin et Fabio Puzzo. Je remercie aussi Victor et Francis. Je veux témoigner toute ma reconnaissance à Randolph Blake et son équipe pour leur accueil chaleureux à l’université de Vanderbilt. Cela a été inestimable d’être immergé au contact direct des personnes qui demain feront la recherche sur mon sujet de thèse : Jan Brascamp, Sam Ling, Eunice Yang, Mink-Suk Kang ou Sang Wook Hong. Je remercie l’université Descartes de m’avoir apporté les financements supplémentaires pour ce séjour, et l’Ecole Doctorale 261 pour m’avoir accordé le financement des trois ans de thèse. Je remercie tout autant Julie Harris pour son accueil à l’université de St. Andrews et Raymond van Ee pour avoir eu la gentillesse de me confier ses données pour mon analyse. Un remerciement spécial à toutes les personnes qui m’ont aidé dans les activités hors-thèse mais couplées à la thèse notamment aux directeurs d’UE qui ont accepté de me confier l’enseignement de 208 h de TD. Je remercie enfin Jennifer Lalanne pour son amour durant ces années si enrichissantes et merci à ma famille d’être là. Je leur dédie cette thèse. xiii Articles associés Chopin, A., Mamassian, P. , & Blake, R. (en préparation). Stereopsis and rivalry are based on perceived rather than physical orientations. Chopin, A., & Mamassian, P. (soumis à Current Biology). Predictive properties of adaptation.
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