시지각에 대한 생태학적 접근
Preface
Vision is a strange and wonderful business. I have been puzzling over its perplexities for 50 years…. the more I learned about physics, optics, anatomy, and visual physiology, the deeper the puzzles got. —p1
Physics, optics, anatomy, and physiology describe facts, but not facts at a level appropriate for the study of perception. In this book I attempt a new level of description. It will be unfamiliar, and it is not fully developed, but it provides a fresh approach where the old perplexities do not block the way. —p1
Why must we seek explanation in either Body or Mind? It is false dichotomy. —p1
Introduction
This is a book about how we see. —p1
This book is a sequel to The perception of the visual world, which came out in 1950. It is rather different, however, because my explanation of vision was then based on the retinal image, whereas it is now based on what I call the ambient optic array. I now believe we must take an ecological approach to the problems of perception.
We are told that vision depends on the eye, which is connected to the brain. I shall suggest 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, we 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 that is what this book is about. —p1
What psychology needs is the kind of thinking that is beginning to be attempted in what is loosely called Systems theory. —p1
See Gibsonian categorization of vision.
Introduction to the Classic Edition
by William M. Mace
By information, Gibson meant structured energy that was information about environmental sources, in contrast to information as structure in an information theoretical sense which implies a sender and a receiver. Gibson’s information is specific to its environmental sources though not a replica or a copy. It certainly is not a stimulus in the sense of energy that triggers a response. Gibson’s information does not come to the animal. The animal goes to it, actively obtaining the information. —p1
Without question, Gibson’s widest impact has been through his concept of Affordance. He had already identified relational properties, in the case of occluding edge phenomena, and he here explores a second class of such properties that are “neither objective nor subjective.” For example, in order to locomote, animals need a stable supporting surface. Where such surfaces exist, the surfaces can be said to support locomotion by the appropriate animals. “Supportability” exists by virtue both of the material nature and arrangement of environmental surfaces as well as the size and capability of specific animals. That is, the surface affords locomotion relative to a specific animal…. Since 1979, the concept of affordance has “gone viral,” to use internet jargon. This is largely attributable to the promotion of Donald Norman whose work has been influential in the interactive design (computers) community. Norman somewhat skewed the meaning of affordance, but he and other writers about design and human factors have offered clarifications and are quick to acknowledge Gibson’s priority as well as their own departures from his original meaning. —p1
Karen Adolph, a student of Eleanor J. Gibson’s, James Gibson’s equally famous wife, followed up her mentor’s well known work with babies on a “visual cliff.” Adolph has now made numerous important contributions to our understanding of the development of infant locomotion and the perception of affordances. (e.g., Adolph & Kretch, 2012) —p1
Part I. The Environment to be Perceived
Chapter 1. The Animal and the Environment
Environment of animals:
In this book, environment will refer to the surroundings of those organisms that perceive and behave, that is to say, animals…. Plants in general are not animate; they do not move about, they do not behave, they lack a nervous system, and they do not have sensations. In these respects they are like the objects of physics, chemistry, and geology…. the surroundings of any animal include other animals as well as the plants and the nonliving things. —p3 (But see Plant intelligence —ak)
The mutuality of animal and environment
The fact is worth remembering because it is often neglected that the words animal and environment make an inseparable pair. Each term implies the other….
Every animal is, in some degree at least, a perceiver and a behaver. It is sentient and animate, to use old-fashioned terms. It is a perceiver of the environment and a behaver in the environment. But this is not to say that it perceives the world of physics and behaves in the space and time of physics.
The difference between the animal environment and the physical world
The world of physics encompasses everything from atoms through terrestrial objects to galaxies…. The size-level at which the environment exists is the intermediate one that is measured in millimeters and meters….
The masses of animals, likewise, are measured within the range of milligrams to kilograms, not at the extremes of the scale, and for good physiological reasons…. In short, the sizes and masses of things in the environment are comparable with those of the animals. —p4
Units of the environment:
Now, with respect to these units, an essential point of theory must be emphasized. The smaller units are embedded in the larger units by what I will call nesting. For example, canyons are nested within mountains; trees are nested within canyons; leaves are nested within trees; and cells are nested within leaves…. There are no atomic units of the world considered as an environment. Instead, these are subordinate and superordinate units. The unit you choose for describing the environment depends on the level of the environment you choose to describe….
We are concerned with direct perception, not so much with the indirect perception got by using microscopes and telescopes or by photographs and pictures, and still less with the kind of apprehension got by speech and writing. These higher-order modes of apprehension will only be considered in Part IV of this book, at the end. —p6
Units of the ground surface:
The literal basis of the terrestrial environment is the ground, the underlying surface of support that tends to be on the average flat - that is to say, a plane - and also level, or perpendicular to gravity…. The fact to be noted now, since it is important for the theory of perspective in Part II, is that these units tend to be repeated over the whole surface of the earth. Grains of sand tend to be of the same size everywhere, and so do pebbles and rocks. —p6
The time scale of the environment: events
The duration of processes at the level of the universe may be measured in millions of years, and the duration of processes at the level of atom may be measured in millionths of a second. But the duration of processes in the environment is measured only in years and seconds. The various life spans of the animals themselves fall within this range….
In this book, emphasis will be placed on events, cycles, and changes at the terrestrial level of the physical world. The changes we shall study are those that occur in the environment. I shall talk about changes, events, and sequences of events but not about time as such. The flow of abstract empty time, however useful this concept may be to the physicist, has no reality for an animal. We perceive not time but processes, changes, sequences, or so I shall assume. —p6
Permanence and change of the layout
Space and time will not often be referred to in this book, but a great deal will be said about permanence and change. Consider the shape of the terrestrial environment, or what may be called its layout. It will be assumed that the layout of the environment is both permanent in some respects and changing in some other respects….
Permanence is relative, of course; that is, it depends on whether you mean persistence over a day, a year, or a millennium. —p8
Persistence in the environment:
The liquids of the world, the streams and oceans, are shaped by the solids, and as for the gaseous matter of the world, the air, it is not shaped at all. I will argue that the air is actually a medium for terrestrial animals.
When a solid substance with a constant shape melts, as a block of ice melts, we say that the object has ceased to exist. This way of speaking is ecological, not physical, for there is physical conservation of matter and mass despite the change from solid to liquid…. Ecology calls this a non-persistence, a destruction of the object, whereas physic calls it a mere change of state. Both assertions are correct, but former is more relevant to the behavior of animals and children…. Even if terrestrial matter cannot be annihilated, a resistant of light-reflecting surface can, and this is what counts for perception….
A wholly invariant environment, unchanging in all parts and motionless but partly movable, a world that is both changeless in many respects and changeable in others but is neither dead at one extreme nor chaotic at the other, is of great important for our inquiry. This fact will become evident later when we talk about the geometry of the environment and its transformations. —p10
Motion in the environment:
So different, in fact, are environmental motions from those studied by Isaac Newton that it is best to think of them as changes of structure rather than changes of position of elementary bodies, changes of form rather than of point locations, or changes in the layout rather than motions in the usual meaning of the term. —p10
Summary
The environment of animals and men is what they perceive. The environment is not the same as the physical world, if one means by that the world described by physics.
The observer and his environment are complementary. So are the set of observers and their common environment.
The components and events of the environment fall into natural units. These units are nested. They should not be confused with the metric units of space and time.
The environment persists in some respects and changes in other respects. The most radical change is going out of existence or coming into existence. —p10
Chapter 2. Medium, Substances, Surfaces
The terrestrial environment is better described in terms of a medium, substances, and the surfaces that separate them. —p12
The medium
Let us begin by noting that our planet consists mainly of earth, water, and air - a solid, a liquid, and a gas…. The interface between any two of these three states of matter constitutes a surface. The earth-water interface at the bottom of a lake is one such, the water-air interface at the top is another, and the earth-air interface is a third - the mosts important of all surfaces for terrestrial animals. This is the ground. It is the ground of their perception and behavior, both literally and figuratively. It is their surface of support….
A gas or a liquid, then, is a medium for animal locomotion. Air is a better medium for locomotion than water because it offers less resistance….
Another characteristic of a gas or liquid medium is that it is generally transparent, transmitting light, whereas a solid is generally opaque, absorbing or reflecting light. A homogeneous medium thus affords vision….
A third characteristic of air or water is that it transmits vibrations or pressure waves outward from a mechanical event, a source of sound waves….
A fourth characteristic is the fact that a medium of air or water allows rapid chemical diffusion whereas the earth does not…. In this way, the medium affords “smelling” of the source, …
The medium thus contains information about things that reflect light, vibrate, or are volatile. By detecting this information, the animal guides and controls locomotion….
The medium in which animals can move about is at the same time the medium for light, sound, and odor coming from sources in the environment…. Any point in the medium is a possible point of observation for any observer who can look, listen, or sniff. And these points of observation are continuously connected to one another by paths of possible locomotion….
All these facts about moving bodies and about the transmission of light, sound, and odor in a medium are consistent with physics, mechanics, optics, acoustics, and chemistry, but they are facts of higher order that have never been made explicit by those science and have gone unrecognized….
Another important characteristic of a medium, it should now be noted, is that it contains oxygen and permits breathing….
Finally, a sixth characteristic of medium for animal life is that it has an intrinsic polarity of up and down. Gravity pulls downward, not upward. Radiant light comes from above, not below, from the sky, not the substratum, and this is as true in the water as in the atmosphere…. The medium is not isotropic, as the physicist says, along this dimension. —p12
The properties of the atmosphere
To sum up, the characteristics of an environmental medium are that it affords respiration or breathing; it permits locomotion; it can be filled with illumination so as to permit vision; it allows detection of vibrations and detection of diffusing emanations; it is homogeneous; and finally; it has an absolute axis of reference, up and down. All these offerings of nature, these possibilities or opportunities, these affordances as I will call them, are invariant. They have been strikingly constant throughout the whole evolution of animal life. —p14
Events in the atmosphere
The atmospheric medium, unlike the underwater medium, is subject to certain kinds of change that we call weather…. The changes are rarely so extreme as to kill off the animals, but they do necessitate various kinds of adaptation and all sorts of behavioral adjustments, such as hibernation, migration, shelter-building, and clothes-wearing. —p15
Substances
… they are more or less resistant to deformation, more or less impenetrable by solid bodies, and more or less permanent in shape. They are usually opaque to light. And the substantial portion of the environment is heterogeneous unlike the medium, which tends to be homogeneous….
Rock, soil, sand, mud clay, oil, tar, wood, minerals, metal, and above all, the various tissues of plants and animals are examples of environmental substances…. A few substances such as clay are amorphous, that is, lacking in structural components, but most of them are geometrical aggregates, that is, they are made of crystals and clumps, of cells and organs, of structures within structures….
When we talk about the composition of a substance, what is it made of, we must keep in mind the level of analysis that is appropriate to the problem being considered.
Why animals need to distinguish among the different substances of the environment is obvious. The substances have different biochemical, physiological, and behavioral effects on the animal. Some are nutritive, some are nonnutritive, and some are toxic….
Substances differ in all sorts of ways. They differ in hardness, … in viscosity, … in cohesiveness, … in elasticity, … in plasticity, … .
A great many substances of the environment, of course, do not change either structurally or chemically, and the nonchange is even more important that the change. It is chiefly on this account that the environment is persistent. But also, even when substances change, they are often restored by processes of growth, compensation, and restitution so that an equilibrium or steady state arises and there is invariance despite change - an invariance of higher order than mere physicochemical persistence. —p15
The status of water: medium of substance?
It is the medium for aquatic animals, not a substance, but it is a substance for terrestrial animals, not the medium…. The animal and its environment, remember, are reciprocal terms…. For us, water falls into the category of substances, not medium….
Some animals, to be sure, can get about in both water and air: the amphibians. They live an interesting life, and how they can perceive in either environment is a problem very much worth study. —p17
Conclusions about substances
To summarize what has been said about substances, they differ in both chemical and physical composition. They are compounded and aggregated in extremely complicated ways and thus do not tend toward homogeneity, as the medium does. They are structued in a hierarchy of nested units. And these different components have very different possibilities for the behavior of animals, for eating, for resisting locomotion, for manipulation, and for manufacture. —p18
Surfaces and the ecological laws of surfaces
The following laws are proposed, without any claim of completeness. The list will serve, however, to focus the discussion, and it also provides an outline of what is to follow. The laws are not independent of one another and must be considered in combination.
- All persisting substances have surfaces, and all surfaces have a layout.
- Any surface has resistance to deformation, depending on the viscosity of the substance.
- Any surface has resistance to disintegration, depending on the cohesion of the substance.
- Any surface has a characteristic texture, depending on the composition of the substance. It generally has both a layout texture and a pigment texture.
- Any surface has a characteristic shape, or large-scale layout.
- A surface may be strongly or weakly illuminated, in light or in shade.
- An illuminated surface may absorb either much or little of the illumination falling on it.
- A surface has a characteristic reflectance, depending on the substance.
- A surface has a characteristic distribution of reflectance ratios of the different wavelengths of the light, depending on the substance. This property is what I will call its color, in the sense that different distributions of constitute different colors. —p19
Substances, surface, layout, and persistence
Resistance to deformation
Resistance to disintegration
Characteristic texture
Characteristic shape
High and low illumination
High and low absorption of light
Characteristic reflectance
Characteristic spectral reflectance
The qualities of substantial surfaces
Summary
We live in an environment consisting of substances that are more or less substantial; of a medium, the gaseous atmosphere; and of the surfaces that separate the substances from the medium. We do not live in “space.”
The medium permits unimpeded locomotion from place to place, and it also permits the seeing, smelling, and hearing of the substances at all places. Locomotion and behavior are continually controlled by the activities of seeing, smelling, and hearing, together with touching.
The substances of the environment need to be distinguished. A powerful way of doing so is by seeing their surfaces.
A surface has characteristic properties that can persist or change, such as its layout, its texture, the property of being lighted or shaded, and the property of reflecting a certain fraction of the illumination falling on it.
Chapter 3. The Meaningful Environment
A nomenclature for surface layout
Surfaces and the medium are ecological terms; planes and space are the nearest equivalent geometrical terms, but note the differences. Planes are colorless; surfaces are colored. Planes are transparent ghosts; surfaces are generally opaque and substantial. The intersection of two planes, a line, is not the same as the junction of two flat surfaces, an edge or corner. —p30
What the environment affords the animal
The environment of any animal (and of all animals) contains substances, surfaces and their layout, enclosures, objects, places, events, and the other animals. This description is very general; it holds true for insects, birds, mammals, and men. Let us now attempt a more particular description, selecting those surfaces, layouts, objects, and events that are of special concern to animals that behave more or less as we do. —p31
Terrain features
An open environment affords locomotion in any direction over the ground, whereas a cluttered environment affords locomotion only at openings….
A path affords pedestrian locomotion from one place to another, between the terrain features that prevent locomotion. The preventers of locomotion consist of obstacles, barriers, water margins, and brinks (the edges of cliffs). A path must afford footing; it must be relatively free of rigid foot-sized obstacles….
An obstacle can be defined as an animal-sized object that affords collision and possible injury. A barrier is a more general case; it may be the face of a cliff, a wall, or a man-made fence….
A water margin prevents pedestrian locomotion; …
A brink, the edge of a cliff, is a very significant terrain feature. It is a falling-off place. It affords injury and therefore needs to be perceived by a pedestrian animal….
A step, or stepping-off place, differs from a brink in size, relative to the size of the animal. It thus affords pedestrian locomotion. A stairway, a layout of adjacent steps, affords both descent and ascent….
A slope is a terrain feature that may or may not afford pedestrian locomotion depending on its angle from the surface of the level ground and its texture….
Humans have been altering the natural features of the terrain for thousands of years, constructing paths, roads, stairways, and bridges over gorges and streams. Paths, roads, stairways, and bridges facilitate human locomotion and obviate climbing. Humans have also been constructing obstacles and barriers to prevent locomotion by enemies, human or animal. —p32
Shelters
The atmospheric medium, it will be remembered, is neither entirely homogeneous nor wholly invariant. Sometimes there is rain in the air, or hail, or snow. Sometimes the wind blows, and in certain latitudes of the earth the air periodically becomes to cold for warm-blooded animals, who will die if they lose more heat to the medium than they gain by oxidizing food. For such reasons, many animals and all human beings must have shelters…. Human animals build what I will call huts - a generic term for simple human artificial shelters.
A hut has a site on the ground, and it is an attached object from the outside. But it also has an inside. Its usual features are, first, a roof that is “get-underneath-able” and thus affords protection from rain and now and direct sunlight; second, walls, which afford protection from wind and prevent the escape of heat; and third, a doorway to afford entry and exit, that is an opening. A hut can be built of sticks, clay, thatch, stones, brick, or many other more sophisticated substances. —p32
Water
… water does not afford respiration to terrestrial animals with lungs, and they are always in danger of drowning…. Animal tissue consists mainly of solutions in water, and the fluids of the body have to be replenished. Animals must drink. —p32
Fire
… we now know that fire is merely a rapid chemical reaction of oxidation, but nevertheless we still perceive a fire as such. It is hardly an object, not a substance, and it has a very unusual surface….
A fire affords warmth even in the open but especially in a shelter. It provides illumination and, in the form of a torch, can be carried about, even into the depths of a cave. But a fire also affords injury to the skin….
Once this control is learned by the adult and the child, fire affords many benefits besides warmth and illumination. It allows the cooking of food substances and boiling of water in pots. It permits the glazing of clay and the reduction of minerals to metals. Fire, like water, has many kinds of meaning, many uses, many values. —p33
Objects
The term object as used in philosophy and psychology is so inclusive as to be almost undefinable. But as I have defined it above, it refers only to a persisting substance with a closed or nearly closed surface and can be either detached or attached. I always refer to a “concrete” object, not an “abstract” one….
An attached object of the appropriate size permits a primate to grasp it, as a monkey grasps a tree branch. (A bird can grasp with its claws in the same way.) Such an object is something to hold on to and permits climbing. A detached object of the appropriate size to be grasped is even more interesting. It affords carrying, that is, it is portable. If the substance has an appropriate mass-to-volume ratio (density), it affords throwing, that is, it is a missile.
A hollow object such as a pot can be used to contain water or wine or grain and to store these substances. An object with a level surface knee-high from the ground can be used to sit on. An elongated object, a stick, if the substance is elastic and flexible, affords bending and thus can be made into a bow for launching arrows. A rigid, straight stick, not bent or curved, can be rotated on its long axis without wobbling; it can be used as a fire drill or as an axle for a wheel. The list of examples could go on without end. —p34
Tools
Tools are detached objects of a very special sort. They are graspable, portable, manipulatable, and usually rigid….
When in use, a tool is a sort of extension of the hand, almost an attachment to it or a part of the user’s own body, and thus is no longer a part of the environment of the user…. This capacity to attach something to the body suggests that the boundary between the animal and the environment is not fixed at the surface of the skin but can shift. More generally it suggests that the absolute duality of “objective” and “subjective” is false. When we consider the affordances of things, we escape this philosophical dichotomy. (See Embodied cognition —ak)
When being worn, clothing, even more than a tool, is a part of the wearer’s body instead of a part of the environment. —p36
Other animals
Like all detached objects, animate objects can be pushed and displaced by external forces, they can fall when pulled by the force of gravity - in short, they can be passively moved - but they also can move actively under the influence of internal forces…. Moreover the style of movement, the mode of deformation, is unique for each animal. These special objects differ in size, shape, texture, color, and in the sounds they emit, but above all they differ in the way they move…. animals have characteristic behavior as well as characteristic anatomies.
Animals are thus by far the most complex objects of perception that the environment presents to an observer. Another animal may be prey or predator, potential mate or rival, adult or young, one’s own young or another’s young. Moreover, it may be temporarily asleep or awake, receptive or unreceptive, hungry or satiated. What the other animal affords is specified by its permanent features and its temporary state, and it can afford eating or being eaten, copulation or fighting, nurturing or nurturance.
What the other animal affords the observer is not only behavior but also social interaction. As one moves so does the other, the one sequence of action being suited to the other in a kind of behavioral loop. All social interaction is of this sort - sexual, maternal, competitive, cooperative - or it may be social grooming, play, and even human conversation.
This brief description does not even begin to do justice to the power of the notion of affordances in social psychology. The old notions of social stimuli and social responses, of biological drives and social instincts are hopelessly inadequate. —p36
Human displays
Finally, we come to a very special class of artificial objects - or perhaps devices is a better term - that display optical information…. A display, to employ a useful generic term, is a surface that has been shaped or processed so as to exhibit information for more than just the surface itself. —p37
The environment of one observer and the environment of all observers
Although it is true that no two individuals can be at the same place at the same time, any individual can stand in all places, and all individuals can stand in the same place at different times. Insofar as the habitat has a persisting substantial layout, therefore, all its inhabitants have an equal opportunity to explore it. In this sense the environment surrounds all observers in the same way that it surrounds a single observer.
The old idea that each observer stands at the center of his or her private world and that each environment is therefore unique gets its main support from a narrow conception of optics and a mistaken theory of visual perception. —p37
Summary
Formal plane geometry has been contrasted with an unformalized and quite unfamiliar geometry of surfaces. But the latter is more appropriate for describing the environment in which we perceive and behave, because a surface can be seen whereas a plan cannot. The differences between a plane and surface have been pointed out.
A tentative list of the main features of surface layout has been proposed. The definitions are subject to revision, but terms of this sort are needed in ecology, architecture, design, the biology of behavior, and the social sciences instead of the places, forms, lines, and points of geometry. The term object, especially, has been defined so as to give it a strictly limited application unlike the general meaning it has in philosophy and psychology.
The fundamental ways in which surface are laid out have an intrinsic meaning for behavior unlike the abstract, formal, intellectual concepts of mathematical space. —p38
Part II. The Information for Visual Perception
Chapter 4. The Relationship Between Stimulation and Stimulus Information
The distinction between luminous and illuminated bodies
The distinction between radiation and illumination
The distinction between radiant light and ambient light
The structuring of ambient light
Stimulation and stimulus information
Do we ever see light as such?
The concept of the stimulus as an application of energy
Ambient energy as available stimulation
The orthodox theory of the retinal image
Summary
Ecological optics is concerned with many-times-reflected light in the medium, that is, illumination. Physical optics is concerned with electromagnetic energy, that is, radiation.
Ambient light coming to a point in the air is profoundly different from radiant light leaving a point source. The ambient light has structure, whereas the radiant light does not. Hence, ambient light makes available information about reflecting surfaces, whereas radiant light can at most transmit information about the atoms from which it comes.
If the ambient light were unstructured or undifferentiated, it would provide no information about an environment, although it would stimulate the photoreceptors of an eye. Thus, there is a clear distinction between stimulus information and stimulation. We do not have sensations of light triggered by stimuli under normal conditions. The doctrine of discrete stimuli does not apply to ordinary vision.
The orthodox theory of the formation of an image on a screen, based on the correspondence between radiating points and focus points, is rejected as the basis for an explanation for ecological vision. This theory applies to the design of optical instruments and cameras, but it is a seductive fallacy to conceive the ocular system in this way. One of the worst results of the fallacy is the inference that the retinal image is transmitted to the brain.
The information that can be extracted from ambient light is not the kind of information that is transmitted over a channel. There is no sender outside the head and no receiver inside the head. —p57
Chapter 5. The Ambient Optic Array
How is ambient light structured? Preliminary considerations
The laws of natural perspective: the intercept angle
Optical structure with a moving point of observation
Perspective structure and invariant structure
The significance of changing perspective in the ambient array
The change between hidden and unhidden surfaces: covering edges
Projected and unprojected surfaces
Going out of and coming into sight
The loci of occlusion: occluding edges
Self-occlusion and superposition
Superposition
The information to specify the continuation of surfaces
The case of very distant surfaces
Summary: The Optics of occlusion
How is ambient light structured? A theory
The sources of invariant optical structure
The sources of variant optical structure
Variants and invariants with a moving source of illumination
Ripples and waves on water: a special case
Summary
Chapter 6. Events and the Information for Perceiving Events
A classification of terrestrial events
Changes of layout due to complex forces
Change of color and texture due to change in composition
Waxing and waning of a surface due to change in the state of matter
Summary: what shall we take as an event?
The optical information for perceiving events
mechanical events
Chemical events
Destruction and creation of surfaces
The kinds of disturbance of optical structure
The causation of events
Summary
Chapter 7. The Optical Information for Self-Perception
The specifying of the self by the field of view
Non-visual information about the self
Egoreception and exteroception are inseparable
The information for the perceiving of distance
The specifying of head turning
The specifying of limb movements
The specifying of locomotion
Summary
Chapter 8. The Theory of Affordances
The niches of the environment
Man’s alteration of the natural environment
Some affordances of the terrestrial environment
The medium
The substances
The surfaces and their layouts
The objects
Other persons and animals
Places and hiding places
Summary: positive and negative affordances
The origin of the concepts of affordances: a recent history
The optical information for perceiving affordances
Misinformation for affordances
Summary
Part III. Visual Perception
Chapter 9. Experimental Evidence for Direct Perception: Persisting Layout
Evidence for the direct perception of surface layout
The psychophysics of space and form perception
Experiments on the perception of a surface as distinguished from nothing
Experiments on the perception of the surface of support
Experiments with the ground as background
Experiments on the perception of slant
Is there evident against the direct perception of surface layout?
Summary
Chapter 10. Experiments on the Perception of Motion in the World and Movement of the Self
The perception of changing surface layout
Apparatus for the study of motion in the frontal plane
Experiments on the kinetic depth effect, or stereokinesis
Experiments with progressive magnification or minification
Experiments with progressive transformations
The puzzle of phenomenal rigidity
An experiment on the perception of separation in depth
Experiments on the perception of collision
The coperception of one’s own movement
The discovery of visual kinesthesis
Experiments with visual kinesthesis
Summary
Chapter 11. The Discovery of the Occluding Edge and Its Implications for Perception
Kaplan’s experiment
Anticipations of the occluding edge
The theory of reversible occlusion
Terminology
Locomotion in a cluttered environment
The motions of detached objects
Head turning
Nonpersisting surfaces
What is seen at this moment from this position does not comprise what is seen
Perception over time from paths of observation
The problem of orientation
The puzzle of ecocentric awareness
Hiding, peeking, and privacy
Summary
Chapter 12. Looking with the Head and Eyes
Looking around and looking at
With what does one see the world
The awareness of the environment and the ego
The visual ego
The persisting environment: Persistence, coexistence, and cconcurrence
How does the eye-head system work? Outline of a new theory
The recognized types of eye movement
A reconsideration of eye movements
Other adjustments of the visual system
Conclusion: the functions of the visual system
The fallacy of the stimulus sequence theory
Theo theory of the conversion of a sequence into a scene
Summary
Chapter 13. Locomotion and Manipulation
The evolution of locomotion and manipulation
Support
Visual perception of support
Manipulation
The control of locomotion and manipulation
The medium contains the information for control
Visual kinesthesis and control
The optical information necessary for control of locomotion
What specifies locomotion or stasis?
What specifies an obstacle or an opening?
What specifies imminent contact with a surface?
What specifies the benefit or injury that lies ahead?
Rules for the visual control of locomotion
Rules for the visual control of manipulation
Manipulation and the perceiving of interior surfaces
Summary
Chapter 14. The Theory of Information Pickup and Its Consequences
What is new about the pickup of information?
A redefinition of perception
A new assertion about what is perceived
The information for perception
The concept of a perceptual system
The registering of both persistence and change
Summary of the theory of pickup
The traditional theories of perception: input processing
Mental operations on the sensory inputs
Semilogical operations on the sensory inputs
Decoding operations on the sensory inputs
The application of memories to the sensory inputs
The false dichotomy between present and past experience
A new approach to nonperceptual awareness
The relationship between imagining and perceiving
A new approach to knowing
Knowing mediated by instruments
Knowing mediated by descriptions: explicit knowledge
Fact and fiction in words and pictures
Knowing and imagining mediated by pictures
Summary
Part IV. Depiction
Chapter 15. Pictures and Visual Awareness
The showing of drawings and the study of perception
What is a picture?
The picture as an array
The picture as a record
A theory of drawing and its development in the child
The fundamental graphic act
Replicating or copying
Drawing proper
The muddle of representation
What about the illusion of reality? The duality of picture perception
The power of perspective in painting
Is depiction a form of description?
The consciousness of the visual field
What is it to see in perspective? Patchwork perspective vs. edge perspective
The principles of line drawing
Summary
Chapter 16. Motion Pictures and Visual Awareness
The changing optic array
The progressive picture
The arrested picture
What can the movies make available?
What does a verbal narration make available?
A theory of filming and film-editing
The composition of a film
The camera and the head of the viewer
The psychology of film-splicing
The theory of montage