Vision and Mind: Selected Readings in the Philosophy of Perception

Total Page:16

File Type:pdf, Size:1020Kb

Vision and Mind: Selected Readings in the Philosophy of Perception ision and Mind Selected Readings in the Philosophy of Perception edited by Alva Noë and Evan Thompson Vision and Mind This Page Intentionally Left Blank Vision and Mind Selected Readings in the Philosophy of Perception edited by Alva Noë and Evan Thompson A Bradford Book The MIT Press Cambridge, Massachusetts London, England © 2002 Massachusetts Institute of Technology All rights reserved. No part of this book may be reproduced in any form by any electronic or mechanical means (including photocopying, recording, or information storage and retrieval) without permission in writing from the publisher. This book was set in Sabon by SNP Best-set Typesetter Ltd., Hong Kong. Printed and bound in the United States of America. Library of Congress Cataloging-in-Publication Data Vision and mind : selected readings in the philosophy of perception / edited by Alva Noë and Evan Thompson. p. cm. Includes bibliographical references and index. ISBN 0-262-14078-0 (alk. paper)—ISBN 0-262-64047-3 (pbk. : alk. paper) 1. Perception (Philosophy) I. Noë, Alva. II. Thompson, Evan. B828.45 .V565 2002 121¢.34—dc21 2002023533 Contents Preface vii Sources ix 1 Introduction 1 Alva Noë and Evan Thompson 2 Selections from Phenomenology of Perception 15 Maurice Merleau-Ponty 3 Some Remarks about the Senses 35 H. P. Grice 4 The Intentionality of Sensation: A Grammatical Feature 55 G. E. M. Anscombe 5 A Theory of Direct Visual Perception 77 James J. Gibson 6 Perception and Its Objects 91 P. F. Strawson 7 Perceptions as Hypotheses 111 Richard L. Gregory 8 Veridical Hallucination and Prosthetic Vision 135 David Lewis 9 Perception, Vision and Causation 151 Paul Snowdon 10 How Direct Is Visual Perception?: Some Reflections on Gibson’s “Ecological Approach” 167 Jerry A. Fodor and Zenon W. Pylshyn vi Contents 11 Selections from Vision 229 David Marr 12 Sensation and the Content of Experience: A Distinction 267 Christopher Peacocke 13 Linking Propositions 289 Davida Y. Teller 14 Molyneux’s Question 319 Gareth Evans 15 Ways of Coloring: Comparative Color Vision as a Case Study for Cognitive Science 351 Evan Thompson, Adrian Palacios, and Francisco J. Varela 16 Conscious Experience 419 Fred Dretske 17 The Content of Perceptual Experience 443 John McDowell 18 On the Function of Visual Representation 459 Dana H. Ballard 19 Seeing Is Believing—Or Is It? 481 Daniel C. Dennett 20 Sensory Substitution and Qualia 497 Paul Bach-y-Rita 21 The Visual Brain in Action 515 A. David Milner and Melvyn A. Goodale 22 What Is a Neural Correlate of Consciousness? 531 David J. Chalmers 23 On the Brain-Basis of Visual Consciousness: A Sensorimotor Account 567 Alva Noë and J. Kevin O’Regan Index 599 Preface The writings in this volume investigate the nature of visual perception. Our goal has been to produce a collection that can serve as a starting point for the philo- sophy of perception. These writings provide, we believe, a clear statement of the central issues confronting the philosophical study of perception today. It is our hope that this volume will make a contribution to their ongoing study. All the works collected here, except for one, have been previously published. Many are classics; most have been important for philosophical discussion of per- ception; all serve, we hope, to indicate clearly an important family of problems. In order to make the book as useful as possible, we have resisted (in all but a few instances) reprinting materials that are easily available elsewhere or that are excerpted from larger works. Vision and Mind has been long in the making. Through several incarnations, it has grown leaner and more focused. We are grateful to many people for advice, criticism, and encouragement. We would like to express our thanks to Ned Block, Justin Broakes, Alex Byrne, Dave Chalmers, Dan Dennett, Sean Kelly, Erik Myin, Luiz Pessoa, Susanna Siegel, and Francisco Varela. We are grateful to the authors and to their original publishers for granting us permission to include their works here. We offer special thanks to Carolyn Gray Anderson and to her predecessor at The MIT Press, Amy Yeager, for their strong support of this project. We also wish to thank Diane Zorn for her help in preparing the manuscript. Finally, A. N. grate- fully acknowledges the support of faculty research funds from the Humanities Divi- sion of the University of California, Santa Cruz. This Page Intentionally Left Blank Sources Maurice Merleau-Ponty. Selections from Phenomenology of Perception. Trans. Colin Smith. London: Routledge & Kegan Paul, [1945] 1962. Reprinted by permission of the publisher. “The ‘sensation’ as a unit of experience.” (pp. 3–12) “Experience and objective thought: The problem of the body.” (pp. 67–72) “The theory of the body is already a theory of perception.” (pp. 203–206) H. P. Grice. “Some remarks about the senses.” In R. J. Butler, ed., Analytic Philosophy, 15–153. Oxford: Basil Blackwell, 1962. Reprinted by permission of the publisher. G. E. M. Anscombe. “The intentionality of sensation: A grammatical feature.” In Metaphysics and the Philosophy of Mind: Collected Philosophical Papers, Vol. III, 3–20. Oxford: Blackwell, 1965. Reprinted by permission of the publisher. James J. Gibson. “A theory of direct visual perception.” In J. R. Royce and W. W. Rozeboom, eds., The Psychology of Knowing, 215–240. New York: Gordon & Breach, 1972. Reprinted by permission of the publisher. P. F. Strawson. “Perception and its objects.” In G. F. Macdonald, ed., Perception and Iden- tity: Essays Presented to A. J. Ayer with His Replies, 41–60. London: Macmillan, 1979. Reprinted by permission of the author and the publisher. Richard L. Gregory. “Perceptions as hypotheses.” Philosophical Transactions of the Royal Society B 290 (1980): 181–197. Reprinted by permission of the author and the Royal Society. David Lewis. “Veridical hallucination and prosthetic perception.” In Australasian Journal of Philosophy 58 (1980): 239–249. Reprinted by permission of the author and the Australasion Journal of Philosophy. D. Lewis, “Postscript.” In Philosophical Papers Volume 2, 287–290. Reprinted by permission of the author. Oxford: Oxford University Press, 1986. Paul Snowdon. “Perception, vision and causation.” Aristotelian Society Proceedings New Series 81 (1980–1981): 175–192. Reprinted by courtesy of the Editor of the Aristotelian Society: © [1981] and by permission of the author. Jerry A. Fodor and Zenon W. Pylyshyn. “How direct is visual perception?: Some reflections on Gibson’s ‘Ecological Approach.’” Cognition 9 (1981): 139–196. Reprinted with permis- sion from Elsevier Science. x Sources David Marr. “Part I: Introduction and Philosophical Preliminaries.” Selections from Vision: A Computational Investigation into the Human Representation and Processing of Visual Information. New York: W. H. Freeman and Company, 1982. Used with permission. “General introduction.” (pp. 3–7) “The philosophy and the approach.” (pp. 8–38) Christopher Peacocke. “Sensation and the content of experience: A distinction.” In Christopher Peacocke, Sense and Content, 4–26. Oxford: Oxford University Press, 1983. Reprinted by permission of Oxford University Press. Davida Y. Teller. “Linking propositions.” Vision Research 24, no. 10 (1984): 1233–1246. Reprinted with permission from Elsevier Science. Gareth Evans. “Molyneux’s question.” In Gareth Evans, Collected Papers, ed. John McDowell, 364–399. Oxford: Oxford University Press, 1985. © Antonia Phillips 1985. Reprinted by permission of Oxford University Press. Evan Thompson, Adrian Palacios, and Francisco J. Varela. “Ways of coloring: Comparative color vision as a case study for cognitive science.” Behavioral and Brain Sciences 15 (1992): 1–26. Reprinted with the permission of the authors and Cambridge University Press. Fred Dretske. “Conscious experience.” Mind 102, no. 406 (1993): 263–283. Reprinted by permission of Oxford University Press. John McDowell. “The content of perceptual experience.” The Philosophical Quarterly 44, no. 175 (1994): 190–205. Reprinted by permission of the editors of The Philosophical Quarterly. Dana H. Ballard. “On the function of visual representation.” In Kathleen Akins, ed., Perception, 111–131. Vancouver Studies in Cognitive Science, vol. 5. Oxford: Oxford University Press, 1996. Used by permission of Oxford University Press, Inc. Daniel C. Dennett. “Seeing is believing—or is it?” In Kathleen Akins, ed., Perception, 158–172. Vancouver Studies in Cognitive Science, vol. 5. Oxford: Oxford University Press, 1996. Used by permission of Oxford University Press, Inc., and by permission of the author. Paul Bach-y-Rita. “Substitution sensorielle et qualia” [Sensory substitution and qualia]. In J. Proust, ed., Perception et Intermodalité, 81–100. Paris: Presses Universitaires de France, 1996. Reprinted by permission of the author. A. David Milner and Melvyn A. Goodale. “The visual brain in action.” Psyche: An Interdisciplinary Journal of Research on Consciousness. Available at ·http://psyche.cs.monash.edu/au/v4/psyche-4-12-milner.htmlÒ. 1998. Reprinted by permission of the authors. David J. Chalmers. “What is a neural correlate of consciousness?” In T. Metzinger, ed., Neural Correlates of Consciousness: Empirical and Conceptual Questions, 17–39. Cambridge, MA: The MIT Press, 2000. Reprinted by permission of the authors and MIT. 1 Introduction Alva Noë and Evan Thompson The philosophy of perception is a microcosm of the metaphysics of mind. Its central problems—What is perception? What is the nature of perceptual consciousness? How can one fit an account of perceptual experience into a broader account of the nature of the mind and the world?—are problems at the heart of metaphysics. It is often justifiably said that the theory of perception (and especially vision) is the area of psychology and neuroscience that has made the greatest progress in recent years. Despite this progress, or perhaps because of it, philosophical problems about per- ception retain a great urgency, both for philosophy and for science. Beyond these general remarks, however, it is difficult to state precisely what the philosophy of perception comprises, and hence which topics, issues, and viewpoints should be included in a book such as this one.
Recommended publications
  • Eye-Movement Studies of Visual Face Perception
    Eye-movement studies of visual face perception Joseph Arizpe A dissertation submitted for the degree of Doctor of Philosophy of the University College London Institute of Cognitive Neuroscience University College London 2015 1 Declaration I, Joseph Arizpe, confirm that the work presented in this thesis is my own. Where information has been derived from other sources, I confirm that this has been indicated in the thesis. 2 Abstract This thesis investigates factors influencing eye-movement patterns during face perception, the relationship of eye-movement patterns to facial recognition performance, and methodological considerations impacting the detection of differences in eye-movement patterns. In particular, in the first study (chapter 2), in which the basis of the other-race effect was investigated, differences in eye- movement patterns during recognition of own- versus other-race (African, Chinese) faces were found for Caucasian participants. However, these eye- movement differences were subtle and analysis-dependent, indicating that the discrepancy in prior reports regarding the presence or absence of such differences are due to variability in statistical sensitivity of analysis methods across studies. The second and third studies (chapters 3 and 4) characterized visuomotor factors, specifically pre-stimulus start position and distance, which strongly influence subsequent eye-movement patterns during face perception. An overall bias in fixation patterns to the opposite side of the face induced by start position and an increasing undershoot of the first ordinal fixation with increasing start distance were found. These visuomotor influences were not specific to faces and did not depend on the predictability of the location of the upcoming stimulus.
    [Show full text]
  • Hershenson (1992) Size-Distance Invariance. Kinetic Invariance Is
    Perception & Psychophysics 1992, 51 (6), 541-548 Size-distance invariance: Kinetic invariance is different from static invariance MAURICE HERSHENSON Brandeis University, Waltham, Massachusetts The static form of the size-distance invariance hypothesisasserts that a given proximal stimu- lus size (visual angle) determines a unique and constant ratio of perceived-object size to perceived object distance. A proposed kinetic invariance hypothesis asserts that a changing proximal stim- ulus size (an expanding or contracting solid visual angle) produces a constant perceived size and a changing perceived distance such that the instantaneous ratio of perceived size to perceived distance is determined by the instantaneous value of visual angle. The kinetic invariance hy- pothesis requires a new concept, an operating constraint, to mediate between the proximal ex- pansion or contraction pattern and the perception of rigid object motion in depth. As a conse- quence of the operating constraint, expansion and contraction patterns are automatically represented in consciousness as rigid objects. In certain static situations, the operation of this constraint produces the anomalous perceived-size-perceived-distance relations called the size- distance paradox. The size-distance invariance hypothesis (SDIH) asserts STATIC INVARIANCE RELATIONSHIP that a given proximal stimulus size (visual angle) deter- mines a unique constant ratio of perceived object size to Traditional Formulation perceived object distance (Epstein, 1977; Epstein, Park, The traditional form of the SDIH is derived from the & Casey, 1961; Kilpatrick & Ittelson, 1953). Is it possible analysis of stationary objects (Epstein, 1977; Gilinsky, to explain the moon illusion and retain this form of the 1951; Ittelson, 1951a; Johansson, 1977; Kilpatrick & It- SDIH? To do so, Kaufman and Rock (1962, 1989; Rock telson, 1953; Weintraub & Gardner, 1970).
    [Show full text]
  • Seeing Black and White
    Seeing Black and White Alan Gilchrist OXFORD UNIVERSITY PRESS Seeing Black and White This page intentionally left blank SEEING BLACK AND WHITE Alan Gilchrist 1 2006 1 Oxford University Press, Inc., publishes works that further Oxford University’s objective of excellence in research, scholarship, and education. Oxford New York Auckland Cape Town Dar es Salaam Hong Kong Karachi Kuala Lumpur Madrid Melbourne Mexico City Nairobi New Delhi Shanghai Taipei Toronto With offices in Argentina Austria Brazil Chile Czech Republic France Greece Guatemala Hungary Italy Japan Poland Portugal Singapore South Korea Switzerland Thailand Turkey Ukraine Vietnam Copyright ᭧ 2006 by Oxford University Press, Inc. Published by Oxford University Press, Inc. 198 Madison Avenue, New York, New York 10016 www.oup.com Oxford is a registered trademark of Oxford University Press All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior permission of Oxford University Press. Library of Congress Cataloging-in-Publication Data Gilchrist, Alan. Seeing black and white / by Alan Gilchrist. p. cm. (Oxford psychology series; no. 40) Includes bibliographical references and index. ISBN 0-19-518716-4 ISBN-13 978-0-19-518716-8 1. Imagery (Psychology). I. Title. II. Series. BF241.L54 2006 153—dc22 2006006283 987654321 Printed in the United States of America on acid-free paper This book is dedicated to the memory of Irvin Rock, my wonderful mentor and warm friend. This page intentionally left blank Foreword And God said let Gilchrist be and all was light.
    [Show full text]
  • A Functional MRI Index of Spatial Context Effects in Vision
    Psychology, 2015, 6, 2145-2154 Published Online December 2015 in SciRes. http://www.scirp.org/journal/psych http://dx.doi.org/10.4236/psych.2015.616211 A Functional MRI Index of Spatial Context Effects in Vision Keith A. Feigenson1,2*, Catherine Hanson3, Thomas Papathomas4, Steven M. Silverstein1,5 1Department of Psychiatry, Robert Wood Johnson Medical School at Rutgers, The State University of New Jersey, Piscataway, USA 2Albright College, Reading, PA, USA 3Rutgers University Brain Imaging Center, Newark, NJ, USA 4Department of Biomedical Engineering and Center for Cognitive Science, Rutgers University, Piscataway, NJ, USA 5University Behavioral Health Care at Rutgers, The State University of New Jersey, Piscataway, NJ, USA Received 25 October 2015; accepted 28 December 2015; published 31 December 2015 Copyright © 2015 by authors and Scientific Research Publishing Inc. This work is licensed under the Creative Commons Attribution International License (CC BY). http://creativecommons.org/licenses/by/4.0/ Abstract Coordination of brain activity, in the form of modulation of feedforward activity by stored infor- mation and expectations, occurs across domains of perception and cognition. A reliable and com- pelling example of this is size contrast in vision. This paper builds on a prior study to show that in healthy humans, the spread of activation in striate and extrastriate visual cortex during a con- text-modulated size perception task is dependent on the perceived size of the target image, not on the physical size of the retinal image. These data provide further evidence that early regions in visual cortex are modulated by top-down influences, and provide a framework for investigating visual context processing in psychiatric disorders where reduced sensitivity to visual contextual effects has been demonstrated in behavioral tasks.
    [Show full text]
  • Combining Cues to Judge Distance and Direction in an Immersive Virtual Reality Environment
    Journal of Vision (2021) 21(4):10, 1–25 1 Combining cues to judge distance and direction in an immersive virtual reality environment Peter Scarfe University of Reading, Earley Gate, Reading, UK Andrew Glennerster University of Reading, Earley Gate, Reading, UK When we move, the visual direction of objects in the most psychophysical experiments, the estimation of environment can change substantially. Compared with visual direction seems simpler and less to do with the our understanding of depth perception, the problem the representation of the 3D world around us. However, visual system faces in computing this change is relatively for a moving observer in a static world, or a static poorly understood. Here, we tested the extent to which observer viewing moving objects, the situation is quite participants’ judgments of visual direction could be different (Wexler et al., 2001). Objects change both predicted by standard cue combination rules. their depth and their visual direction and, in both cases, Participants were tested in virtual reality using a if an observer is to perceive a stable 3D world, they head-mounted display. In a simulated room, they judged must take account of changes in the visual direction of the position of an object at one location, before walking objects just as much as they do for changes in object to another location in the room and judging, in a second depth. interval, whether an object was at the expected visual There is good evidence that people are able to update direction of the first. By manipulating the scale of the room across intervals, which was subjectively invisible their estimate of the visual direction of previously to observers, we put two classes of cue into conflict, one viewed objects when they move to a new location (Foo that depends only on visual information and one that et al., 2005; Klatzky et al., 2003; Klier et al., 2008; uses proprioceptive information to scale any Loomis et al., 1998; Medendorp, 2011; Rieser & Rider, reconstruction of the scene.
    [Show full text]
  • Visual Immersion in the Context of Wall Displays Arnaud Prouzeau, Anastasia Bezerianos, Olivier Chapuis
    Visual Immersion in the Context of Wall Displays Arnaud Prouzeau, Anastasia Bezerianos, Olivier Chapuis To cite this version: Arnaud Prouzeau, Anastasia Bezerianos, Olivier Chapuis. Visual Immersion in the Context of Wall Displays. Interactive Surfaces and Spaces Surfaces Companion Proceedings, Nov 2016, Niagara Falls, Canada. 10.1145/3009939.3009945. hal-01383587 HAL Id: hal-01383587 https://hal.archives-ouvertes.fr/hal-01383587 Submitted on 18 Oct 2016 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Visual Immersion in the Context of Wall Displays Abstract Arnaud Prouzeau Immersion is the subjective impression of being deeply LRI – Univ Paris Sud, CNRS, involved in a specific situation, and can be sensory or cog- Inria, Université Paris-Saclay F-91405 Orsay, France nitive. In this position paper, we use a basic model of visual [email protected] perception to study how ultra-high resolution wall displays can provide visual immersion. With their large size, depend- ing on the position of viewers in front of them, wall displays Anastasia Bezerianos can provide a surrounding and vivid environment. Users LRI – Univ Paris Sud, CNRS, close to the wall can have their visual field filled by the wall Inria, Université Paris-Saclay and they are able to see clearly a large amount information F-91405 Orsay, France [email protected] with a fine resolution.
    [Show full text]
  • Chapter 6 Visual Perception
    Chapter 6 Visual Perception Steven M. LaValle University of Oulu Copyright Steven M. LaValle 2019 Available for downloading at http://vr.cs.uiuc.edu/ 154 S. M. LaValle: Virtual Reality Chapter 6 Visual Perception This chapter continues where Chapter 5 left off by transitioning from the phys- iology of human vision to perception. If we were computers, then this transition might seem like going from low-level hardware to higher-level software and algo- rithms. How do our brains interpret the world around us so effectively in spite of our limited biological hardware? To understand how we may be fooled by visual stimuli presented by a display, you must first understand how our we perceive or interpret the real world under normal circumstances. It is not always clear what we will perceive. We have already seen several optical illusions. VR itself can be Figure 6.1: This painting uses a monocular depth cue called a texture gradient to considered as a grand optical illusion. Under what conditions will it succeed or enhance depth perception: The bricks become smaller and thinner as the depth fail? increases. Other cues arise from perspective projection, including height in the vi- Section 6.1 covers perception of the distance of objects from our eyes, which sual field and retinal image size. (“Paris Street, Rainy Day,” Gustave Caillebotte, is also related to the perception of object scale. Section 6.2 explains how we 1877. Art Institute of Chicago.) perceive motion. An important part of this is the illusion of motion that we perceive from videos, which are merely a sequence of pictures.
    [Show full text]
  • The Moon Illusion Explained Introduction and Summary
    The Moon Illusion Explained Finally! Why the Moon Looks Big at the Horizon and Smaller When Higher Up. Don McCready Professor Emeritus, Psychology Department University of Wisconsin-Whitewater Whitewater, WI 53190 Email to: mccreadd at uww.edu Introduction and Summary [This Section and all other Sections Were Revised November 10, 2004] [Technical Notes on the Murray, Boyaci, & Kersten (2006) experiment were added in June, 2006.] For many centuries, scientists have been puzzled by the common illusion that the rising moon at the horizon looks considerably larger than it does later, at higher elevations toward the zenith of the sky. For at least nine centuries they have known that the angular subtense of the moon's horizontal (azimuth) diameter always measures about 0.52 degrees at an earthly observation point no matter where the moon is in the sky. In other words, there is no physical (optical) reason why the horizon moon should look larger than the zenith moon. Because the moon's angular size remains constant, photographs of the horizon moon and zenith moon taken with the same camera settings yield images which are the same size, as represented by Figure 1. Such pictures prove that the earth's atmosphere certainly does not "magnify" the horizon moon. Figure 1: This sketch represents what a double- exposure photograph of the horizon moon and zenith moon looks like. The two moon images have the same diameter on the film (and a print) because the angle the endpoints of the moon's diameter subtend at a camera lens remains the same. Many researchers have taken such photos in order to convince themselves.
    [Show full text]
  • Visual Space Perception
    8 Empiricist View: Perceived Size and Shape The classical empiricist analysis of perceived size and perceived shape is based on two invariance hypotheses: the size-distance invariance hypothesis (SDIH) and the shape-slant invariance hypothesis (SSIH). An entirely dif- ferent approach to these problems—Gibson’s psychophysical view—is de- scribed in the next chapter. A review of the vast literature on the topics contained in these two chapters can be found in Sedgwick (1986). Perceived Size of Afterimages The proximal stimulus produced by a distal object of size S at distance D from the observer was described in chapter 6: tan α = S/D. Recall that, in this distal-proximal relationship, size is a property of the object and distance refers to the space between the viewer and the object. Consequently, physical size and physical distance are independent quantities. In contrast, the corresponding quantities in the perceptual world, perceived size s and perceived distance d, are not independent; they are properties of perceptual experience. The discussion of perceived size and distance begins with after- images. It describes Emmert’s law of afterimage size and its use as a model for the perceived size of objects. Emmert’s Law of Afterimages An afterimage is a visual image that is seen after the physical stimulus is removed. It may be formed by looking at a light or an illuminated object and then looking away at a surface. An image of the object or the light will be seen on the surface. The image has a deªnite size and shape, and appears to be at the same distance from the viewer as the surface upon which it is projected.
    [Show full text]
  • Transcranial Direct Current Stimulation of the Frontal Eye Field
    Transcranial Direct Current Stimulation of the Frontal Eye Field to Modulate Eye Movements Faculty of Social and Behavioural Sciences, Psychology Master Thesis Psychology, Brain and Cognition Name: Floris Jan Frederik Willem Roelofs Student NumBer: 10212434 Supervisor: Leon Reteig Date: 18/07/2017 Word count: 5119 Abstract The main focus of this study is to validate the results presented By Kanai et al. (2012). In their study they have found indicative data for a modulatory role of the Frontal Eye Fields (FEF) induced By transcranial direct current stimulation (tDCS) on saccade latencies. Because the data did not fully suBstantiate the hypothesised results and the effect sizes Were mild, the aim of this study is to find more conclusive evidence on the modulatory role of the FEF and the influence of tDCS. By taking the design from Kanai et al. (2012) as reference, suBjects received Both anodal and cathodal stimulation during a prosaccade task over the course of two sessions in Which saccade latency Was measured. To estimate the effects of tDCS over time, Baseline measurements Were compared to suBsequent stimulation and post stimulation Blocks. A repeated measure ANOVA over 18 suBjects revealed no significant effects of stimulation on saccade latency and accuracy. It seems like the data does not support the findings of Kanai et al. (2012) in Which tDCS stimulation successfully reached and influenced the FEF. Implications for future research are discussed, as Well as shortcomings and alternative theoretical interpretations of the current data. Introduction With the rising interest and applicability of transcranial direct current stimulation (tDCS), much research arises on the effects of tDCS on different Brain regions.
    [Show full text]
  • Explaining the Moon Illusion
    Explaining the moon illusion Lloyd Kaufman*† and James H. Kaufman‡ *Psychology Department, Long Island University, C.W. Post Campus, 720 Northern Boulevard, Brookville, NY 11548-1309; and ‡IBM Research Division, Almaden Research Center, 350 Harry Road, San Jose, CA 95120 Communicated by Julian Hochberg, Columbia University, New York, NY, October 25, 1999 (received for review August 23, 1999) An old explanation of the moon illusion holds that various cues place the horizon moon at an effectively greater distance than the elevated moon. Although both moons have the same angular size, the horizon moon must be perceived as larger. More recent explanations hold that differences in accommodation or other factors cause the elevated moon to appear smaller. As a result of this illusory difference in size, the elevated moon appears to be more distant than the horizon moon. These two explanations, both based on the geometry of stereopsis, lead to two diametrically opposed hypotheses. That is, a depth interval at a long distance is associated with a smaller binocular disparity, whereas an equal Fig. 1. Regardless of its elevation, the distance between an observer (at the depth interval at a smaller distance is associated with a larger center of the horizontal line) and the moon remains constant (unfilled circles). disparity. We conducted experiments involving artificial moons However, a moon perceived as growing closer as its elevation increases (filled and confirmed the hypothesis that the horizon moon is at a greater circles), must appear as growing smaller. perceptual distance. Moreover, when a moon of constant angular size was moved closer it was also perceived as growing smaller, which is consistent with the older explanation.
    [Show full text]
  • Visual Illusion of the Change of the Size Of
    SPATIUM International Review UDC 72.012 No. 22, July 2010, pp. 38-46 Scientific analysis or debate VISUAL ILLUSION OF THE CHANGE OF THE SIZE OF ARCHITECTURAL AND URBAN OBJECTS OBSERVED UPON A CHANGE OF THE OBSERVER’S DISTANCE: PARAMETERS THAT INFLUENCE IT PHENOMENOLOGICALLY Đorđe Đorđević1, University of Belgrade, Faculty of Architecture, Belgrade, Serbia Gordana Vujić, University of Belgrade, Faculty of Architecture, Belgrade, Serbia This paper explores the visual phenomena of a seeming change of the target-object’s size (as a focus of concrete visual perception) in the function of an observer’s motion so that it “seems” contrary to the law of linear perspective (in the sense of an expected increase of the target volume/monumentality – by getting closer or a decrease - by getting farther away). This phenomenon is described in a geometrical and perceptual aspect; the result of this comprehensive approach led to identify parameters that determine it phenomenologically. It was established that the explored visual phenomenon is a specific “size illusion”, i.e. an “angular size illusion” that occurs when influenced by factors of the perceptual kind - activated by a specific dynamic relationship (on a visual plan) between the target object and its surrounding competitive objects, as an observer moves. By understanding the character of this phenomenon (both in a geometrical and perceptual sense), it is possible to apply the acquired knowledge in practice – in programming the visual effects to be obtained (such as to visually optimize or minimize
    [Show full text]