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What Can Drawing Expertise Tell Us About Visual and Memory

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What Can Drawing Expertise Tell Us About Visual and Memory THESE DE DOCTORAT DE L’UNIVERSITE PARIS DESCARTES Cognition, Comportements et Conduites Humaines (ED 261) Laboratoire Psychologie de la Perception (UMR 8242) 45 rue des Saints Pères, 75006 Paris, France WHAT CAN DRAWING EXPERTISE TELL US ABOUT VISUAL AND MEMORY MECHANISMS? QU'EST-CE QUE L'EXPERTISE EN DESSIN PEUT NOUS DIRE A PROPOS DU FONCTIONNEMENT DE LA VISION ET DE LA MEMOIRE VISUELLE? Florian Perdreau Pour l’obtention du grade de docteur de l’Université Paris Descartes en Sciences Cognitives Patrick Cavanagh Directeur de thèse DATE DE LA SOUTENANCE 7 novembre 2014 MEMBRES DU JURY Pr. Patrick Cavanagh Université Paris Descartes Examinateur Dr. Thérèse Collins Université Paris Descartes Examinateur Pr. Pieter Medendorp Radboud University Nijmegen Rapporteur Pr. Robert Pepperell Cardiff School of Art and Design Examinateur Dr. Jérôme Sackur Ecole Normale Supérieure Examinateur Pr. Johan Wagemans K.U. Leuven Rapporteur Résumé La précision en dessin a été considérablement étudiée chez l’enfant, mais la raison pour laquelle certains adultes sont bien plus précis que d’autres à copier des objets ou des scènes demeure un mystère. Un facteur possible serait l’entrainement : les artistes passent des milliers d’heures à faire des dessins. Le but de cette thèse a été d’explorer dans quelle mesure cet entrainement intensif a pu affecter certains processus de la vision et de la mémoire visuelle. Dans une série d’études, nous avons tout d’abord démontré que l’expertise en dessin n’est pas liée à une perception plus véridique du monde. En effet, les artistes professionnels et les étudiants en Art que nous avons testé n’étaient pas davantage capables de défaire les mécanismes perceptifs automatiques qui corrigent d’ordinaire les effets dus au contexte visuel. Ils étaient autant affectés par les constances visuelles que les novices. Ceci suggère qu’un entrainement en dessin ne pourrait pas affecter des mécanismes perceptifs déjà bien établis, mais plutôt des processus de plus haut ordre, tels que l’analyse visuelle de structure d’objets. Dans deux études, nous avons ensuite cherché à déterminer comment les dessinateurs encodent et intègrent les informations structurelles lorsqu’ils analysent un objet pour le dessiner. Tout d’abord, afin de tester si les artistes avaient une meilleure représentation de formes complexes, nous avons élaboré une tâche de fenêtre contingente dans laquelle les participants devaient classer un objet comme structurellement possible ou impossible alors qu’ils ne pouvaient voir qu’une portion de l’objet centrée sur la position du regard. Les experts étaient capables de faire cette tâche avec de plus petites portions de l’objet. La compétence en dessin serait ainsi liée à la capacité d’intégrer des échantillons d’informations extraits lors de chaque fixation en une représentation interne plus robuste. Nous avons ensuite voulu savoir si la précision en dessin pouvait aussi être liée à l’efficacité de l’encodage des informations structurelles à partir d’une seule fixation (sans mouvements oculaires autorisés), avec l’objet centré soit sur la position de la fixation ou en périphérie visuelle. Nous avons trouvé que les sujets entrainés étaient capables de discriminer des objets impossibles d’objets possibles avec des durées de présentation plus courtes, que ce soit en vision centrale ou périphérique. Enfin, nous avons étudié le rôle de la mémoire visuelle pendant le processus de dessin et cherché à déterminer si les dessinateurs avaient une représentation plus précise de la position des traits de l’objet. Pour cela, nous avons développé une expérience couplant une tâche de dessin sur tablette graphique et une tâche de détection de changement durant laquelle les participants devaient copier une figure sur une tablette graphique. Tout au long du processus de copie, des changements pouvaient intervenir à la fois sur la figure originale et sur la copie, et les participants devaient corriger tout changement détecté, (la figure et le dessin n’étaient visibles qu’en alternance). Nos résultats ont montré que tous nos participants détectaient mieux les changements présents dans la figure originale que dans leur propre dessin. De plus, les experts en dessin était bien meilleurs à détecter les changements, mais seulement lorsque le dessin était impliqué (contrasté avec une simple tâche de détection de changement sans dessin). Pris ensembles, ces résultats démontrent qu’un entrainement intensif en dessin peut affecter des mécanismes perceptifs de haut niveau ainsi que des mécanismes de mémoire visuelle, et non les mécanismes perceptifs basiques déjà bien établis par la longue expérience perceptive que nous partageons tous. 5 Abstract Drawing accuracy has been extensively studied in children, but very little is known of what would make some adults more accurate in copying objects or scenes than many others. One factor may simply be practice: artists have often spent thousands of hours making drawings. The focus of this thesis has been to explore how this intensive practice has affected visual and memory processes. In a series of studies, we first demonstrated that drawing expertise does not relate to a more veridical perception of the world: professional artists and art students were no better than novices at seeing scenes accurately – at undoing the automatic perceptual mechanisms that ordinarily correct for visual context like shadows and depth (visual constancies). This suggests that intensive training in drawing may not affect already well-established perceptual mechanisms, but might affect higher-order processes such as visual analysis of object structure. In a number of studies, we next investigated how trained draftspersons visually encode and integrate structural information when analyzing an object. First, to test whether artists had a more advanced ability to represent complex shapes, we designed a gaze-contingent moving window task where participants had to classify an object as structurally possible or impossible, while only being able to see a portion of the object centered on the gaze position. Experts were able to perform this task with smaller samples of the object. This result suggests that skill in drawing relates to the ability to integrate local samples from each fixation into a more robust internal representation. We then asked whether drawing accuracy could also be related to the encoding efficiency of structural information from a single fixation (no eye movements allowed), with the test object centered at fixation or located in peripheral vision. In this case, we found that experts could discriminate possible vs impossible objects with shorter presentation durations and this was true whether the object was presented at fixation or in the periphery. Finally, we investigated the role of visual memory during the drawing process and whether more skilled participants have a better representation of feature locations. To do so, we designed an interactive pen tablet experiment coupled with a change detection task where participants had to copy a figure on a pen tablet. Throughout the copying process, changes could occur in both the original figure and the copy and participants had to correct any changes they noticed (the figure and the drawing were visible in alternation). We found that all participants detected changes better when they occurred in the original than in their own drawing. Moreover, experts were better at detecting changes, but only when drawing was involved (contrasted with a simple change detection task without drawing). Taken together these results demonstrate that intensive training in drawing affects higher-order perceptual and visual memory mechanisms but not basic perceptual mechanisms that already well-grounded on the life-long perceptual experiences that we all share. 6 1 TABLE OF CONTENTS 1 TABLE OF CONTENTS 7 8 1 TABLE OF CONTENTS 7 2 ACKNOWLEDGMENTS 11 3 INTRODUCTION 15 3.1 PROLOGUE 17 3.2 POTENTIAL SOURCES OF DRAWING SKILL 19 3.2.1 EXTERNAL SOURCES OF DRAWING SKILL: TECHNIQUES, RULES AND KNOWLEDGE 20 3.2.2 DEVELOPMENT OF PERCEPTUAL-MOTOR ABILITIES LINKED TO DRAWING SKILL 20 3.3 VISUOMOTOR ASPECTS OF DRAWING SKILL 22 3.3.1 FINE MOTOR SKILL 22 3.3.2 COORDINATE TRANSFORMATION 23 3.3.3 EFFICIENCY OF EYE-HAND COUPLING STRATEGY IN DRAWING 24 3.4 PERCEPTUAL MECHANISMS RELATED TO DRAWING SKILL 25 3.4.1 PERCEPTUAL MODE INVOLVED IN DRAWING 26 3.4.2 INFLUENCE OF OBJECT KNOWLEDGE ON DRAWING SKILL 28 3.4.3 GLOBAL VS. LOCAL VISUAL PROCESSING OF OBJECTS 31 3.5 VISUAL ANALYSIS AND MEMORY OF OBJECTS STRUCTURES 33 3.5.1 PERCEPTUAL CONSTRAINTS IN DRAWING 33 3.5.2 ENCODING EFFICIENCY AND THE CHUNKING HYPOTHESIS 34 3.5.3 MEMORY OF OBJECT STRUCTURE 36 4 EXPERIMENTS 39 4.1 COULD THE “INNOCENT EYE” HYPOTHESIS ACCOUNT FOR DRAWING SKILL? 41 4.1.1 OBJECTIVES AND SUMMARY OF RESULTS 41 4.1.2 DO ARTISTS SEE THEIR RETINAS? 43 4.2 DRAWING EXPERTS ARE BETTER ABLE TO ACCUMULATE OBJECT STRUCTURE ACROSS EYE- MOVEMENTS. 67 4.2.1 OBJECTIVES AND SUMMARY OF RESULTS 67 4.2.2 THE ARTIST’S ADVANTAGE: BETTER INTEGRATION OF OBJECT INFORMATION ACROSS EYE- MOVEMENTS 68 4.3 ENCODING OF STRUCTURAL INFORMATION FROM INDIVIDUAL FIXATIONS 93 4.3.1 OBJECTIVES AND SUMMARY OF RESULTS 93 4.3.2 DRAWING SKILL RELATES TO THE EFFICIENCY OF ENCODING OBJECT STRUCTURE 95 4.4 SPECIALIZED VISUAL MEMORY ENGAGED ONLY DURING THE DRAWING PROCESS 127 9 4.4.1 OBJECTIVES AND SUMMARY OF RESULTS 127 4.4.2 DRAWING EXPERTS HAVE BETTER VISUAL MEMORY — BUT ONLY WHILE DRAWING 129 5 GENERAL DISCUSSION 153 5.1 MAIN ISSUES OF THE THESIS 155 5.2 DISCUSSION OF THE MAIN RESULTS 156 5.2.1 IS AN ARTIST’S PERCEPTION MORE VERIDICAL? 156 5.2.2 DRAWING SKILL AS PERCEPTUAL EXPERTISE? 157 5.2.3 THE CHUNKING HYPOTHESIS 158 5.2.4 DRAWING IS NOT PLAYING CHESS: THE SPECIFICITY OF EXPERTISE IN DRAWING 162 5.2.5 TALENT VS TRAINING 163 5.3 CONCLUSION 164 6 BIBLIOGRAPHY 167 10 2 ACKNOWLEDGMENTS 2 ACKNOWLEDGMENTS 11 12 First of all, I would like to thank Patrick Cavanagh for having supervised my work during these last four years.
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