Since its publication in 1959, Individuals has become a modern philosophical classic. Bold in scope and ambition, it continues to influence debates in metaphysics, philosophy of logic and language, and epistemology. Peter Strawson's most famous work, it sets out to describe nothing less than the basic subject matter of our thought. It contains Strawson's now famous argument for descriptive metaphysics and his repudiation of revisionary metaphysics, in which reality is something beyond the world of appearances. Throughout, Individuals advances some highly (...) influential and controversial ideas, such as 'non-solipsistic consciousness' and the concept of a person a 'primitive concept'. (shrink)

Large changes that occur in clear view of an observer can become difficult to notice if made during an eye movement, blink, or other such disturbance. This change blindness is consistent with the proposal that focused visual attention is necessary to see change, with a change becoming difficult to notice whenever conditions prevent attention from being automatically drawn to it. -/- It is shown here how the phenomenon of change blindness can provide new results on the nature of visual attention, (...) including estimates of its capacity and the extent to which it can bind visual properties into coherent descriptions. It is also shown how the resultant characterization of attention can in turn provide new insights into the role that it plays in the perception of scenes and events. (shrink)

Change blindness is the striking failure to see large changes that normally would be noticed easily. Over the past decade this phenomenon has greatly contributed to our understanding of attention, perception, and even consciousness. The surprising extent of change blindness explains its broad appeal, but its counterintuitive nature has also engendered confusions about the kinds of inferences that legitimately follow from it. Here we discuss the legitimate and the erroneous inferences that have been drawn, and offer a set of requirements (...) to help separate them. In doing so, we clarify the genuine contributions of change blindness research to our understanding of visual perception and awareness, and provide a glimpse of some ways in which change blindness might shape future research. (shrink)

This paper suggests that certain traditional ways of analysing the self start off in situations that are abstract or detached from normal experience, and that the conclusions reached in such approaches are, as a result, inexact or mistaken. The paper raises the question of whether there are more contextualized forms of self- consciousness than those usually appealed to in philosophical or psychological analyses, and whether they can be the basis for a more adequate theoretical approach to the self. First, we (...) develop a distinction between abstract and contextualized actions and intentions by drawing on evidence from studies of rehabilitation after brain damage, and we introduce the notion of intentional attitude. Second, we discuss several interesting conclusions drawn from theoretically and experimentally abstract approaches. These conclusions raise some important issues about both the nature of the self and reflexive consciousness. At the same time they indicate the serious limita- tions concerning what we can claim about self and self-consciousness within such abstract frameworks. Such limitations motivate the question of whether it is possible to capture a sense of self that is more embedded in contextualized actions. Specifically, our concern is to focus on first-person approaches. We identify two forms of self-consciousness, eco- logical self-awareness and embedded reflection, that (1) function within the kinds of contextualized activity we have indicated, and (2) can be the basis for a theoretical account of the self. Both forms of self-consciousness are closely tied to action and promise to provide a less abstract basis for developing a theoretical approach to the self. (shrink)

This paper suggests that certain traditional ways of analysing the self start off in situations that are abstract or detached from normal experience, and that the conclusions reached in such approaches are, as a result, inexact or mistaken. The paper raises the question of whether there are more contextualized forms of self-consciousness than those usually appealed to in philosophical or psychological analyses, and whether they can be the basis for a more adequate theoretical approach to the self. First, we develop (...) a distinction between abstract and contextualized actions and intentions by drawing on evidence from studies of rehabilitation after brain damage, and we introduce the notion of intentional attitude. Second, we discuss several interesting conclusions drawn from theoretically and experimentally abstract approaches. These conclusions raise some important issues about both the nature of the self and reflexive consciousness. At the same time they indicate the serious limitations concerning what we can claim about self and self-consciousness within such abstract frameworks. Such limitations motivate the question of whether it is possible to capture a sense of self that is more embedded in contextualized actions. Specifically, our concern is to focus on first-person approaches. We identify two forms of self-consciousness, ecological self-awareness and embedded reflection, that function within the kinds of contextualized activity we have indicated, and can be the basis for a theoretical account of the self. Both forms of self-consciousness are closely tied to action and promise to provide a less abstract basis for developing a theoretical approach to the self. (shrink)

In an earlier paper, "Non-conceptual Content and the 'Space of Reasons'", I distinguished two forms of the view that perceptual content is non-conceptual, which I called the 'state view' and the 'content view'. On the latter, but not the former, perceptual states have a different kind of content than do cognitive states. Many have found it puzzling why anyone would want to make this claim and, indeed, what it might mean. This paper attempts to address these questions.

Since its publication in 1959, Individuals has become a modern philosophical classic. Bold in scope and ambition, it continues to influence debates in metaphysics, philosophy of logic and language, and epistemology. Peter Strawson's most famous work, it sets out to describe nothing less than the basic subject matter of our thought. It contains Strawson's now famous argument for descriptive metaphysics and his repudiation of revisionary metaphysics, in which reality is something beyond the world of appearances. Throughout, Individuals advances some highly (...) influential and controversial ideas, such as 'non-solipsistic consciousness' and the concept of a person a 'primitive concept'. (shrink)

Describes the various senses as sensory systems that are attuned to the environment. Develops the notion of rich sensory information that specifies the distal environment. Includes a discussion of affordances.

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. (shrink)

Hurley’s is a difficult book to work through—partly because of its length and the complexity of its arguments, but also because each of the ten essays of which it is composed has a rather different starting point and focus, and because few of her arguments achieve real closure. Essay 2 discusses competing interpretations of Kant, essay 4 articulates nonconceptual forms of self-consciousness, essay 5 offers fresh interpretations of commissurotomy patients’ behavior, essay 6 develops an objection to Wittgenstein on rule following, (...) essay 8 attacks an alleged assumption of externalism, and chapter 10 explores the possibility of combining a “motor theory” and a “control theory” of perception. This is a very rich brew, and at least half the challenge this book presents consists in discerning its central argument and conclusion with enough precision to bring criticism to bear. (shrink)

Challenging and rewarding in equal measure, _Phenomenology of Perception_ is Merleau-Ponty's most famous work. Impressive in both scope and imagination, it uses the example of perception to return the body to the forefront of philosophy for the first time since Plato. Drawing on case studies such as brain-damaged patients from the First World War, Merleau-Ponty brilliantly shows how the body plays a crucial role not only in perception but in speech, sexuality and our relation to others.

What is the role of conscious visual experience in the control and guidance of human behaviour? According to some recent treatments, the role is surprisingly indirect. Conscious visual experience, on these accounts, serves the formation of plans and the selection of action types and targets, while the control of 'online' visually guided action proceeds via a quasi-independent non-conscious route. In response to such claims, critics such as (Wallhagen [2007], pp. 539-61) have suggested that the notions of control and guidance invoked (...) are unacceptably vague, and that that the image of 'zombie systems' guiding action fails to take account of the possibility that there is genuine but unconceptualized, unnoticed, and/or unreportable experience taking place and guiding or controlling the actions. I address both sets of concerns. I try to show that refining and clarifying the key notions of control and guidance leaves the original argument intact, as does the appeal to unconceptualized, unnoticed, or unreportable experiences. The exercise serves, however, to highlight an important complex of considerations concerning the relations between control, agency, and experience. Better understanding these relations is, I suggest, an important source of insights concerning the nature of phenomenal experience. (shrink)

First published in 1945, Maurice Merleau-Ponty’s monumental _Phénoménologie de la perception _signalled the arrival of a major new philosophical and intellectual voice in post-war Europe. Breaking with the prevailing picture of existentialism and phenomenology at the time, it has become one of the landmark works of twentieth-century thought. This new translation, the first for over fifty years, makes this classic work of philosophy available to a new generation of readers. _Phenomenology of Perception _stands in the great phenomenological tradition of Husserl, (...) Heidegger, and Sartre. Yet Merleau-Ponty’s contribution is decisive, as he brings this tradition and other philosophical predecessors, particularly Descartes and Kant, to confront a neglected dimension of our experience: the lived body and the phenomenal world. Charting a bold course between the reductionism of science on the one hand and "intellectualism" on the other, Merleau-Ponty argues that we should regard the body not as a mere biological or physical unit, but as the body which structures one’s situation and experience within the world. Merleau-Ponty enriches his classic work with engaging studies of famous cases in the history of psychology and neurology as well as phenomena that continue to draw our attention, such as phantom limb syndrome, synaesthesia, and hallucination. This new translation includes many helpful features such as the reintroduction of Merleau-Ponty’s discursive Table of Contents as subtitles into the body of the text, a comprehensive Translator’s Introduction to its main themes, essential notes explaining key terms of translation, an extensive Index, and an important updating of Merleau-Ponty’s references to now available English translations. Also included is a new foreword by Taylor Carman and an introduction to Merleau-Ponty_ _by Claude Lefort. Translated by Donald A. Landes. (shrink)

How the Body Shapes the Mind is an interdisciplinary work that addresses philosophical questions by appealing to evidence found in experimental psychology, neuroscience, studies of pathologies, and developmental psychology. There is a growing consensus across these disciplines that the contribution of embodiment to cognition is inescapable. Because this insight has been developed across a variety of disciplines, however, there is still a need to develop a common vocabulary that is capable of integrating discussions of brain mechanisms in neuroscience, behavioural expressions (...) in psychology, design concerns in artificial intelligence and robotics, and debates about embodied experience in the phenomenology and philosophy of mind. Shaun Gallagher's book aims to contribute to the formulation of that common vocabulary and to develop a conceptual framework that will avoid both the overly reductionistic approaches that explain everything in terms of bottom-up neuronal mechanisms, and inflationistic approaches that explain everything in terms of Cartesian, top-down cognitive states. Gallagher pursues two basic sets of questions. The first set consists of questions about the phenomenal aspects of the structure of experience, and specifically the relatively regular and constant features that we find in the content of our experience. If throughout conscious experience there is a constant reference to one's own body, even if this is a recessive or marginal awareness, then that reference constitutes a structural feature of the phenomenal field of consciousness, part of a framework that is likely to determine or influence all other aspects of experience. The second set of questions concerns aspects of the structure of experience that are more hidden, those that may be more difficult to get at because they happen before we know it. They do not normally enter into the content of experience in an explicit way, and are often inaccessible to reflective consciousness. To what extent, and in what ways, are consciousness and cognitive processes, which include experiences related to perception, memory, imagination, belief, judgement, and so forth, shaped or structured by the fact that they are embodied in this way? (shrink)

Marc Jeannerod is director of the Institut des Sciences Cognitives in Lyon. His work in neuropsychology focuses on motor action. The idea that there is an essential relationship between bodily movement, consciousness, and cognition is not a new one, but recent advances in the technologies of brain imaging have provided new and detailed support for understanding this relationship. Experimental studies conducted by Jeannerod and his colleagues at Lyon have explored the details of brain activity, not only as we are actively (...) moving, but as we plan to move, as we imagine moving, and as we observe others move. His work also captures important distinctions between pathological and non-pathological experience. In The Cognitive Neuroscience of Action , Jeannerod focussed on object-oriented actions. What happens in the brain and what do we experience when we reach to grasp an object? How do we plan an action of that sort? To what extent does explicit motor imagery contribute to such action? What role does a motor representation or motor schema play in the accomplishment of action? At the very end of that book he raises questions that seem quite different. How is it possible to understand the intentions of others? Precisely what mechanisms allow us to imitate other people's actions? In more recent years much of Jeannerod's work has been in pursuit of these questions about interaction with others, and he has helped to show that there are intimate connections between moving ourselves and understanding others. Jeannerod's work does not lack important implications for a philosophical understanding of human activity. Although in contemporary philosophical debates on consciousness one can still find arguments that simply ignore bodily movement as an important factor in cognition, several recent works have returned to serious consideration of movement and action . In the following interview Jeannerod discusses many issues relevant to the philosophy of mind and action, including concepts of intentionality, movement and consciousness of movement, the role of simulation in understanding others, and the best way to conceptualize brain processes in all of these regards. Importantly, he makes constant reference to the empirical evidence, much of it developed in his own experimental studies. (shrink)

Two major functions of the visual system are discussed and contrasted. One function of vision is the creation of an internal model or percept of the external world. Most research in object perception has concentrated on this aspect of vision. Vision also guides the control of object-directed action. In the latter case, vision directs our actions with respect to the world by transforming visual inputs into appropriate motor outputs. We argue that separate, but interactive, visual systems have evolved for the (...) perception of objects on the one hand and the control of actions directed at those objects on the other. This 'duplex' approach to high-level vision suggests that Marrian or 'reconstructive' approaches and Gibsonian or 'purposive-animate-behaviorist' approaches need not be seen as mutually exclusive, but rather as complementary in their emphases on different aspects of visual function. (shrink)

How do rational minds make contact with the world? The empiricist tradition sees a gap between mind and world, and takes sensory experience, fallible as it is, to provide our only bridge across that gap. In its crudest form, for example, the traditional idea is that our minds consult an inner realm of sensory experience, which provides us with evidence about the nature of external reality. Notoriously, however, it turns out to be far from clear that there is any viable (...) conception of experience which allows it to do the job. The original problem is to show that thought is rationally constrained by external reality. If sensory experience is to provide the solution--in particular, if it is to provide the answer to sceptical challenges--it must therefore meet two criteria. First, it must itself be `receptive'--i.e., appropriately constrained by external reality. Second, it must be the kind of thing that can enter into a logical or rational relationship with belief--it must already be `conceptual,' in other words. In arguing against the idea that anything could serve both roles, Wilfred Sellars termed this conception of experience "the Myth of the Given.". (shrink)

The 'content view', in slogan form, is 'Perceptual experiences have representational content'. I explain why the content view should be reformulated to remove any reference to 'experiences'. I then argue, against Bill Brewer, Charles Travis and others, that the content view is true. One corollary of the discussion is that the content of perception is relatively thin (confined, in the visual case, to roughly the output of 'mid-level' vision). Finally, I argue (briefly) that the opponents of the content view are (...) partially vindicated, because perceptual error is due to false belief. (shrink)

Glover offers an account for why some pictorial illusions influence early but not late phases of an action. His proposed corrective control process, however, functions normally in the absence of continuous visual information, suggesting that the stimulus is registered veridically prior to action onset. Here I consider an alternative account, based on differing informational constraints of behaviors (and phases of behaviors).

Evidence for a dichotomy between the planning of an action and its on-line control in humans is reviewed. This evidence suggests that planning and control each serve a specialized purpose utilizing distinct visual representations. Evidence from behavioral studies suggests that planning is influenced by a large array of visual and cognitive information, whereas control is influenced solely by the spatial characteristics of the target, including such things as its size, shape, orientation, and so forth. Evidence from brain imaging and neuropsychology (...) suggests that planning and control are subserved by separate visual centers in the posterior parietal lobes, each constituting part of a larger network for planning and control. Planning appears to rely on phylogenetically newer regions in the inferior parietal lobe, along with the frontal lobes and basal ganglia, whereas control appears to rely on older regions in the superior parietal lobe, along with the cerebellum. Key Words: action; apraxia; control; illusions; optic ataxia; PET; planning; reaching;. (shrink)

In "The Quest for Consciousness," Caltech neuroscientist Christof Koch explores the biological basis of consciousness.

This book is a tour-de-force on how human consciousness may have evolved. From the "phantom pain" experienced by people who have lost their limbs to the uncanny faculty of "blindsight," Humphrey argues that raw sensations are central to all conscious states and that consciousness must have evolved, just like all other mental faculties, over time from our ancestorsodily responses to pain and pleasure. '.

One of the more powerful impressions created by vision is that of a coherent, richly-detailed world where everything is present simultaneously. Indeed, this impression is so compelling that we tend to ascribe these properties not only to the external world, but to our internal representations as well. But results from several recent experiments argue against this latter ascription. For example, changes in images of real-world scenes often go unnoticed when made during a saccade, flicker, blink, or movie cut. This "change (...) blindness" provides strong evidence against the idea that our brains contain a picture-like representation of the scene that is everywhere detailed and coherent. (shrink)

Although the mechanics of how the eye works are well understood, debate still exists as to how the complex machinery of the brain interprets neural impulses...

The same neural structures involved in the unconscious modeling of our acting body in space also contribute to our awareness of the lived body and of the objects that the world contains. Neuroscientific research also shows that there are neural mechanisms mediating between the multi-level personal experience we entertain of our lived body, and the implicit certainties we simultaneously hold about others. Such personal and body-related experiential knowledge enables us to understand the actions performed by others, and to directly decode (...) the emotions and sensations they experience. A common functional mechanism is at the basis of both body awareness and basic forms of social understanding: embodied simulation. It will be shown that the present proposal is consistent with some of the perspectives offered by phenomenology. (shrink)

Table of Contents Acknowledgments 1 Self-Consciousness and the Body: An Interdisciplinary Introduction by Naomi Eiland, Anthony Marcel and José Luis Bermúdez 2 The Body Image and Self-Consciousness by John Campbell 3 Infants’ Understanding of People and Things: From Body Imitation to Folk Psychology by Andrew N. Meltzoff and M. Keith Moore 4 Persons, Animals, and Bodies by Paul F. Snowdon 5 An Ecological Perspective on the Origins of Self by George Butterworth 6 Objectivity, Causality, and Agency by Thomas Baldwin 7 (...) At Two with Nature: Agency and the Development of Self-World Dualism by James Russell 8 Ecological Perception and the Notion of a Nonconceptual Point of View by José Luis Bermúdez 9 Proprioception and the Body Image by Brian O’Shaughnessy 10 Awareness of One’s Own Body: An Attentional Theory of Its Nature, Development, and Brain Basis by Marcel Kinsbourne 11 Body Schema and Intentionality by Shaun Gallagher 12 Living without Touch and Peripheral Information about Body Position and Movement: Studies with Deafferented Subjects by Jonathan Cole and Jacques Paillard 13 Bodily Awareness: A Sense of Ownership by M. G. F. Martin 14 Bodily Awareness and the Self by Bill Brewer 15 Introspection and Bodily Self-Ascription by Quassim Cassam 16 Consciousness and the Self by Naomi Eilan Contributors Index. (shrink)

This is a book about how we see: the environment around us (its surfaces, their layout, and their colors and textures); where we are in the environment; whether or not we are moving and, if we are, where we are going; what things are good for; how to do things (to thread a needle or drive an automobile); or why things look as they do.The basic assumption is that vision depends on the eye which is connected to the brain. The (...) author suggests that natural vision depends on the eyes in the head on a body supported by the ground, the brain being only the central organ of a complete visual system. When no constraints are put on the visual system, people look around, walk up to something interesting and move around it so as to see it from all sides, and go from one vista to another. That is natural vision—and what this book is about. (shrink)

I offer an explanation of how subjects are able to perceive the intrinsic spatial properties of objects, given that subjects always perceive from a particular location. The argument proceeds in two steps. First, I argue that a conception of space is necessary to perceive the intrinsic spatial properties of objects. This conception of space is spelled out by showing that perceiving intrinsic properties requires perceiving objects as the kind of things that are perceivable from other locations. Second, I show that (...) having such a conception of space presupposes that a subject represent her location in relation to perceived objects. More precisely the thesis is that a subject represents her location as the location from which she both perceives objects and would act in relation to objects were she to act. So I argue that perception depends on the capacity to know what it would be to act in relation to objects. (shrink)

Artificial intelligence research has foundered on the issue of representation. When intelligence is approached in an incremental manner, with strict reliance on interfacing to the real world through perception and action, reliance on representation disappears. In this paper we outline our approach to incrementally building complete intelligent Creatures. The fundamental decomposition of the intelligent system is not into independent information processing units which must interface with each other via representations. Instead, the intelligent system is decomposed into independent and parallel activity (...) producers which all interface directly to the world through perception and action, rather than interface to each other particularly much. The notions of central and peripheral systems evaporateeverything is both central and peripheral. Based on these principles we have built a very successful series of mobile robots which operate without supervision as Creatures in standard office environments. (shrink)

Much as we would like to conceive empirical thought as rationally grounded in experience, pitfalls await anyone who tries to articulate this position, and ...

Recent work in "embodied, embedded" cognitive science links mental contents to large-scale distributed effects: dynamic patterns implicating elements of (what are traditionally seen as) sensing, reasoning and acting. Central to this approach is an idea of biological cognition as profoundly "action-oriented" - geared not to the creation of rich, passive inner models of the world, but to the cheap and efficient production of real-world action in real-world context. A case in point is Hurley's (1998) account of the profound role of (...) motor output in fixing the contents of conscious visual awareness - an account that also emphasizes distributed vehicles and long-range dynamical loops. Such stories can seem dramatically opposed to accounts, such as Milner and Goodale (1995), that stress relatively local mechanisms and that posit firm divisions between processes of visual awareness and of visuomotor action. But such accounts, I argue, can be deeply complimentary and together illustrate an important lesson. The lesson is that cognition may be embodied and action-oriented in two distinct - but complimentary - ways. There is a way of being embodied and action-oriented that implies being closely geared to the fine-grained control of low level effectors (hands, arms, legs and so on). And there is a way of being embodied and action-oriented that implies being closely geared to gross motor intentions, current goals, and schematic motor plans. Human cognition, I suggest, is embodied and action-oriented in both these ways. But the neural systems involved, and the size and scope of the key dynamic loops, may be quite different in each case. (shrink)

How should we characterize the functional role of conscious visual experience? In particular, how do the conscious contents of visual experience guide, bear upon, or otherwise inform our ongoing motor activities? According to an intuitive and (I shall argue) philosophically influential conception, the links are often quite direct. The contents of conscious visual experience, according to this conception, are typically active in the control and guidance of our fine-tuned, real-time engagements with the surrounding three-dimensional world. But this idea (which I (...) shall call the Assumption of Experience-Based Control) is hostage to empirical fortune. It is a hostage, moreover, whose safety is in serious doubt. Thus Milner and Goodale (1995) argue for a deep and abiding dissociation between the contents of conscious seeing, on the one hand, and the resources used for the on-line guidance of visuo-motor action, on the other. This ‘dual visual systems’ hypothesis, which finds many echoes in various other bodies of cognitive scientific research, poses a prima facie challenge to the Assumption of Experience-Based Control. More importantly, it provides (I shall argue) fuel for an alternative and philosophically suggestive account of the functional role of conscious visual experience. (shrink)

According to representionalists, qualia-the introspectible properties of sensory experience-are exhausted by the representational contents of experience. Representationalists typically advocate an informational psychosemantics whereby a brain state represents one of its causal antecedents in evolutionarily determined optimal circumstances. I argue that such a psychosemantics may not apply to certain aspects of our experience, namely, our experience of space in vision, hearing, and touch. I offer that these cases can be handled by supplementing informational psychosemantics with a procedural psychosemantics whereby a representation (...) is about its effects instead of its causes. I discuss conceptual and empirical points that favor a procedural representationalism for our experience of space. (shrink)

In discussions of perception and its relation to knowledge, it is common to distinguish what one comes to believe on the basis of perception from the distinctively perceptual basis of one's belief. The distinction can be drawn in terms of propositional contents: there are the contents that a perceiver comes to believe on the basis of her perception, on the one hand; and there are the contents properly attributed to perception itself, on the other. Consider the content.

b>: The problem of how physical systems, such as brains, come to represent themselves as subjects in an objective world is addressed. I develop an account of the requirements for this ability that draws on and refines work in a philosophical tradition that runs from Kant through Peter Strawson to Gareth Evans. The basic idea is that the ability to represent oneself as a subject in a world whose existence is independent of oneself involves the ability to represent space, and (...) in particular, to represent oneself as one object among others in an objective spatial realm. In parallel, I provide an account of how this ability, and the mechanisms that support it, are realized neurobiologically. This aspect of the article draws on, and refines, work done in the neurobiology and psychology of egocentric and allocentric spatial representation. (shrink)

If you stare for a period of time at a scene which contains movement in one direction, and then turn your attention to an object in a scene which contains no movement, this object will appear to move in the opposite direction to that of the original movement. The effect can be easily achieved by attaching a piece of paper with a spiral drawn on it to the spinning turntable of a record player, and then turning the turntable off while (...) continuing to look at the spiral (see Frisby 1979, pp. 100-101 for a detailed descrip- tion of how to bring this about). But the illusion of movement can also occur when looking at a waterfall, for instance, and turning one's attention away from the waterfall to a stationary object such as a stone; hence its name - the 'Waterfall Illusion'. (shrink)