SPECIAL ISSUE: ‘IS THE VISUAL WORLD A GRAND ILLUSION?’

Edited by Alva Noë

There is a traditional scepticism about whether the world "out there" really is as we perceive it. A new breed of hyper-sceptics now challenges whether we even have the perceptual experience we think we have. According to these writers, perceptual consciousness is a kind of false consciousness. This view grows out of the discovery of such phenomena as change blindness and inattentional blindness, which show that we can all be quite blind to changes taking place before our very eyes. Such radical scepticism has acute and widespread implications for the study of perception and consciousness. The writings collected in this volume explore these implications. The contributors are scientists and philosophers at the forefront of this research, and include well-known authors such as psychologists Susan Blackmore and Arien Mack, and philosophers Andy Clark and Daniel Dennett. They have an gift for bringing these paradoxical issues to life and sharing their excitement with the non-specialist.

TABLE OF CONTENTS

Contributors
Editor’s Preface
Alva Noë
Is the Visual World a Grand Illusion?   abstract    full text
Daniel C. Dennett
How Could I Be Wrong? How Wrong Could I Be?   abstract
Susan Blackmore
There Is No Stream of Consciousness   abstract
Bruce Bridgeman
The Grand Illusion and Petit Illusions: Interactions of Perception and Sensory Coding   abstract
Eric Schwitzgebel
How Well Do We Know Our Own Conscious Experience?
The Case of Visual Imagery   abstract
Dana H. Ballard
Our Perception of the World Has To Be an Illusion   abstract
Temre N. Davies, Donald D. Hoffman & Antonio M. Rodriguez
Visual Worlds: Construction Or Reconstruction?   abstract
Frank H. Durgin
The Tinkerbell Effect: Motion Perception and Illusion   abstract
Arien Mack
Is  the Visual World a Grand Illusion? A Response   abstract
Daniel T. Levin
Change Blindness Blindness As Visual Metacognition   abstract
Charles Siewert
Is Visual Experience Rich Or Poor?   abstract
Jonathan Cohen
The Grand Grand Illusion Illusion   abstract
Mark Rowlands
Two Dogmas of Consciousness   abstract
Andy Clark
Is Seeing All It Seems? Action, Reason and the Grand Illusion  abstract

ABSTRACTS

Alva Noë

Is the Visual World a Grand Illusion?     full text

In this paper I explore a brand of scepticism about perceptual experience that takes its start from recent work in psychology and philosophy of mind on change blindness and related phenomena. I argue that the new scepticism rests on a problematic phenomenology of perceptual experience. I then consider a strengthened version of the sceptical challenge that seems to be immune to this criticism. This strengthened sceptical challenge formulates what I call the problem of perceptual presence. I show how this problem can be addressed by drawing on an enactive or sensorimotor approach to perceptual consciousness. Our experience of environmental detail consists in our access to that detail thanks to our possession of practical knowledge of the way in which what we do and sensory stimulation depend on each other.

Alva Noë, Department of Philosophy, University of California at Santa Cruz, Santa Cruz, CA 95064, USA. anoe@cats.ucsc.edu

Daniel C. Dennett

How Could I Be Wrong? How Wrong Could I Be?

One of the striking, even amusing, spectacles to be enjoyed at the many workshops and conferences on consciousness these days is the breathtaking overconfidence with which laypeople hold forth about the nature of consciousness — their own in particular, but everybody’s by extrapolation. Everybody’s an expert on consciousness, it seems, and it doesn’t take any knowledge of experimental findings to secure the home truths these people enunciate with such conviction.

One of my goals over the years has been to shatter that complacency, and secure the scientific study of consciousness on a proper footing. There is no proposition about one’s own or anybody else’s conscious experience that is immune to error, unlikely as that error might be. I have come to suspect that refusal to accept this really quite bland denial of what would be miraculous if true lies behind most if not all the elaboration of fantastical doctrines about consciousness recently defended. This refusal fuels the arguments about the conceivability of zombies, the importance of a ‘first-person’ science of consciousness, ‘intrinsic intentionality’ and various other hastily erected roadblocks to progress in the science of consciousness.

Daniel C. Dennett, Center for Cognitive Studies, Tufts University, 520 Boston Avenue,  Medford, MA 02155-5555, USA. daniel.dennett@tufts.edu

Susan Blackmore

There Is No Stream of Consciousness

What is all this? What is all this stuff around me; this stream of experiences that I seem to be having all the time?

Throughout history there have been people who say it is all illusion. I think they may be right. But if they are right what could this mean? If you just say ‘It’s all an illusion’ this gets you nowhere — except that a whole lot of other questions appear. Why should we all be victims of an illusion instead of seeing things the way they really are? What sort of illusion is it anyway? Why is it like that and not some other way? Is it possible to see through the illusion? And if so what happens next.

These are difficult questions, but if the stream of consciousness is an illusion, we should be trying to answer them rather than more conventional questions about consciousness. I shall explore these questions though I cannot claim that I will answer them. In doing so I shall rely on two methods. First, there are the methods of science, based on theorising and hypothesis testing — on doing experiments to find out how the world works. Second, there is disciplined observation — watching experience as it happens to find out how it really seems. This sounds odd. You might say that your own experience is infallible — that if you say it is like this for you then no one can prove you wrong. I only suggest you look a bit more carefully. Perhaps then it won’t seem quite the way you thought it did before. I suggest that both these methods are helpful for penetrating the illusion — if illusion it is.

Susan Blackmore, c/o Imprint Academic, PO Box 1, Thorverton, Devon, UK. sjb_ac@hotmail.com

Bruce Bridgeman

The Grand Illusion and Petit Illusions: Interactions of Perception and Sensory Coding

The Grand Illusion, the experience of a rich phenomenal visual world supported by a poor internal representation of that world, is echoed by petit illusions of the same sort. We can be aware of several aspects of an object or pattern, even when they are inconsistent with one another, because different neurological mechanisms code the various aspects separately. They are bound not by an internal linkage, but by the structure of the world itself. Illusions exploit this principle by introducing inconsistencies into normally consistent patterns of stimulation.

Bruce Bridgeman, Department of Psychology, University of California at Santa Cruz,  Santa Cruz, CA 95064, USA. bruceb@cats.ucsc.edu

Andy Clark

Is Seeing All It Seems? Action, Reason and the Grand Illusion

We seem, or so it seems to some theorists, to experience a rich stream of highly detailed information concerning an extensive part of our current visual surroundings. But this appearance, it has been suggested, is in some way illusory. Our brains do not command richly detailed internal models of the current scene. Our seeings, it seems, are not all that they seem. This, then, is the Grand Illusion. We think we see much more than we actually do. In this paper I shall (briefly) rehearse the empirical evidence for this rather startling claim, and then critically examine a variety of responses. One especially interesting response is a development of the so-called ‘skill theory’, according to which there is no illusion after all. Instead, so the theory goes, we establish the required visual contact with our world by an ongoing process of active exploration, in which the world acts as a kind of reliable, interrogable, external memory (Noë et al., 2000; Noë, 2001). The most fully worked-out versions of this response (Noë and O’Regan, 2000; O’Regan and Noë, 2001)) tend, however, to tie the contents of conscious visual experience rather too tightly to quite low-level features of this ongoing sensorimotor engagement. This (I shall argue) undervalues the crucial links between perceptual experience, reason and intentional action, and opens the door to a problem that I will call ‘sensorimotor chauvinism’: the premature welding of experiential contents to very specific details of our embodiment and sensory apparatus. Drawing on the dual visual systems hypothesis of Milner and Goodale (1995), I sketch an alternative version of the skill theory, in which the relation between conscious visual experience and the low-level details of sensori- motor engagement is indirect and non-constitutive. The hope is thus to embrace the genuine insights of the skill theory response, while depicting conscious visual experience as most tightly geared to knowing and reasoning about our world.

Andy Clark, Cognitive Sciences Program, Indiana University, Bloomington, IA 4705, USA. andy@indiana.edu

Dana H. Ballard

Our Perception of the World Has To Be an Illusion

Our seamless perception of the world depends very much on the slow time scales used by conscious perception. Time scales longer than one second are needed to assemble conscious experience. At time scales shorter than one second, this seamlessness quickly deteriorates. Numerous experiments reveal the fragmentary nature of the visual information used to construct visual experience. Models of how the brain manages these fragments use the construct of a routine, which is a task-specific fragment of a sensory-motor program. This paper provides an overview of some of the experiments that test these models. Its aim is to show how the structures that they elucidate constrain the understanding of conscious perception.

Dana H. Ballard, Department of Computer Science, University of Rochester, Rochester, NY 14627, USA. dana@cs.rochester.edu

Jonathan Cohen

The Grand Grand Illusion Illusion

This paper considers a number of ways of understanding the hypothesis that change blindness and inattentional blindness reveal a grand illusion about visual perception. It argues that the most prominent readings of this hypothesis in the literature are untenable. It concludes that, while these results have much to teach us about perception, the only illusion they can be said to uncover is a modest and familiar one.

Jonathan Cohen, Department of Philosophy, University of California at San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0119, USA. joncohen@aardvaak.ucsd.edu

Frank H. Durgin

The Tinkerbell Effect: Motion Perception and Illusion

A new motion illusion is discussed in relation to the idea of vision as a Grand Illusion. An experiment shows that this ‘Tinkerbell effect’ is a good example of a visual illusion supported by low-level stimulus information, but resulting from integration principles probably necessary for normal perception.

Frank H. Durgin, Department of Psychology, Swarthmore College, 500 College Avenue, Swarthmore, PA 19081, USA. fdurgin1@swarthmore.edu

Temre N. Davies, Donald D. Hoffman and Antonio M. Rodriguez

Visual Worlds: Construction Or Reconstruction?

Psychophysical studies of change blindness indicate that, at any instant, human observers are aware of detail in few parts of the visual field. Such results suggest, to some theorists, that human vision reconstructs only a few portions of the visual scene and that, to bridge the resulting representational gaps, it often lets physical objects serve as their own short-term memory. We propose that human vision reconstructs no portion of the visual scene, and that it never lets physical objects serve as their own short-term memory.

Temre N. Davies, Department of Cognitive Sciences, University of California at Irvine,  Irvine, CA 92697, USA. daviest@uci.edu

Donald D. Hoffman, Department of Cognitive Sciences, University of California at Irvine, Irvine, CA 92697, USA. dhoffman@orion.oac.uci.edu

Antonio M. Rodriguez, Department of Cognitive Sciences, University of California at  Irvine, Irvine, CA 92697, USA. tonyr@uci.edu

Daniel T. Levin

Change Blindness Blindness As Visual Metacognition

Many experiments have demonstrated that people fail to detect seemingly large visual changes in their environment. Despite these failures, most people confidently predict that they would see changes that are actually almost impossible to see. Therefore, in at least some situations visual experience is demonstrably not what people think it is. This paper describes a line of research suggesting that overconfidence about change detection reflects a deeper metacognitive error (which we refer to as ‘change blindness blindness’, or CBB) founded on beliefs about attention and the role of meaning as a support for a coherent perceptual experience. Accordingly, CBB does not occur in all situations (subjects can, indeed, make accurate predictions about change detection in some circumstances), while the scope of the phenomenon remains broad enough to suggest more than a misunderstanding of a small niche of visual experience. I finish by arguing that despite the very small amount of research on visual metacognition, these beliefs are critical to understand.

Daniel Levin, Dept of Psychology, PO Box 5190, Kent State University, Kent, OH 44242-0001, USA. dlevin@kent.edu

Arien Mack

Is the Visual World a Grand Illusion? A Response

The question of whether the visual world is a grand illusion is addressed and answered negatively. The question only arises because of the recent work on Inattentional Blindness (IB), Change Blindness (CB) and the Attentional Blink (AB) which establishes that attention is necessary for perception. It is argued that IB occurs only when attention is narrowly focussed and not when attention is more broadly distributed, which is the more typical attentional state. Under conditions of distributed attention we are likely to have a fuller, if less detailed, impression of the visual scene, which may be why we are so surprised by demonstrations of IB, AB and CB. It is also argued that the question about the possible illusory quality of our perceptual world cannot be avoided by denying that inattention causes blindness and asserting instead that it causes amnesia. This argument is grounded on the similarity between these phenomena and visual neglect and by evidence that priming by the unseen stimuli occurs in each case indicating that the stimuli to which we are functionally blind are processed and represented in implicit memory. The adaptive utility of this information is discussed.

Arien Mack, Psychology Department, New School for Social Research, 65 Fifth Avenue,  New York City, NY 10003, USA. mackarie@newschool.edu

Mark Rowlands

Two Dogmas of Consciousness

Most recent discussions of phenomenal consciousness are predicated on two deeply entrenched assumptions. The first is objectualism, the claim that what it is like to undergo an experience is something of which we are or can be aware in the having of that experience. The second is internalism, the claim that what it is like to undergo an experience is constituted by states, events and processes that are located inside the skins of experiencing subjects. This paper argues that both assumptions should be rejected. What it is like to undergo an experience is not an object of consciousness but something that exists in the directing of consciousness towards (non-phenomenal) objects. What it is like to undergo an experience is not something of which we are aware, but something in virtue of which we are aware. And there is little reason for supposing that the directing of consciousness towards its objects is something that occurs exclusively inside the skins of experiencing subjects. On the contrary, directing of consciousness towards its objects is often extended, involving acts of worldly probing and exploration.

Mark Rowlands, Department of Philosophy, University College Cork, Cork, Ireland. mrowlands@philosophy.ucc.ie

Eric Schwitzgebel

How Well Do We Know Our Own Conscious Experience? The Case of Visual Imagery

Philosophers tend to assume that we have excellent knowledge of our own current conscious experience or ‘phenomenology’. I argue that our knowledge of one aspect of our experience, the experience of visual imagery, is actually rather poor. Precedent for this position is found among the introspective psychologists of the late nineteenth and early twentieth centuries. Two main arguments are advanced toward the conclusion that our knowledge of our own imagery is poor. First, the reader is asked to form a visual image, and it is expected that answering questions about certain basic features of that experience will be difficult. If so, it seems reasonable to suppose that people could be mistaken about those basic features of their own imagery. Second, it is observed that although people give widely variable reports about their own experiences of visual imagery, differences in report do not systematically correlate with differences on tests of skills that psychologists have often supposed to require visual imagery, such as mental rotation, visual creativity, and visual memory.

Eric Schwitzgebel, Department of Philosophy, University of California at Riverside, Riverside, CA 92521- 0201, USA. eschwitz@citrus.ucr.edu

Charles Siewert

Is Visual Experience Rich Or Poor?

I will argue that, once certain crucial distinctions are acknowledged, and the issues interpreted in their light, we will have reason to reject ‘grand illusion’ interpretations of change and inattentional blindness research. Further, as a result of this critique, we are led to question the assumption sometimes made that our visual experiences are only as rich as our internal visual representations (i.e., descriptions or images formed in our heads) are detailed. My conclusions thus provide additional support for some important aspects of the Noë–Pessoa– Thompson perspective mentioned earlier.

Charles Siewert, Department of Philosophy, University of Miami, PO Box 248054, Coral Gables, FL 33124, USA. csiewert@miami.edu

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