——–

“Physics, optics, anatomy, and physiology describe facts, but not facts at a level appropriate for the study of perception.” (Gibson, preface)

Move from the idea of the retinal image to the ambient optic array.

Natural vision. Evolved visual system.

Retinal image | ambient optic array | contraints | snapshot vision | aperature vision | ambient vision | ambulatory vision |

“First, the environment must be described, since what there is to be perceived has to be stipulated before one can even talk about perceiving it. This is not the world of physics but the world at the level ecology.”

“Second, the information available for perception in an illuminated medium must be described. This is not just light for stimulating receptors but the information in the light that can activate the system. Ecological optics is required instead of classical optics.”

“Third (and only here do we come to what is called psychology proper), the process of perception must be described. This is not the processing of sensory inputs, however, but the extracting of invariants from the stimulus flux. The old idea that sensory inputs are converted into perceptions by operations of the mind is rejected. A racially new way of thinking about perception is proposed.”

“I am also asking the reader to suppose that the concept of space has nothing to do with perception. Geometrical space is a pure abstraction. Outer space can be visualized but cannot be soon. The cues for depth refer only to paintings, nothing more. The visual third dimension is a misapplication of Descarte's notion of three axes for a coordinate system.”

“The doctrine that we could not perceive the world around us unless we already had the concept of space is nonsense. It is quite the other way around: We could not conceive of empty space unless we could see the ground under our feet and the sky above. Space is a myth, a ghost, a fiction for geometers.”

“By information, Gibson meant structured energy that was information about environmental sources, in contrast to information as structure in an informational theoretical sense which implies a sender and a received. Gibsons' 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.”

“Placing the topics of depiction (pictures and film) at the end of the book (Part IV) highlights Gibon's view that these are higher-order phenomena that depend first on how perceiving in the real environment works. Pictures, especially for Gibson, are derivative, not foundational.”

“Thus, instead of emphasizing the plasticity of the eye-brain-body systems, Gibson emphasized what had to be true about the world for the perceptual system to arrive at an equilibrium.”

Thinkers influenced by Gibson Donald Norman | William H. Warren Jr. | Karen Adolph | David N. Lee | E.H. Gombrich | John M. Kennedy | Rudolf Arnhem | Nikolai Bernstein | Esterh Thelen | Reuben Baron | Leslie Zebrowitz | Kerry Marsh | Carol Fowler | Fred and Merrelyn Emery | Harry Heft | Tim Ingold | David L. Webster | Arakawa | Madeline Gins, Michael Benedikt | Scott Kelso | Arthur Iberall | Naoto Fukasawa | Gilbert Gottlieb | Joe Anderson | Barbara Anderson | David Boardwell | Marilyn Nonken | Eric Clarke | John Searle | Jack Sanders | Ruth Millikan | Ian Hutchby

“In this book, environment will refer to the surroundings of those organisms that perceive and behave, that is to say, animals.”

“The world can be described at different levels, and one can choose which level to being with. Biology begins with the division between the non-living and the living. But psychology begins with the division between the inanimate and the animate, and this is where we choose to begin.”

“We are more interested in ways of life than in heredity.”

“The environment consists of the surroundings of animals. Let us observe that in one sense the surroundings of a single animal are the same as the surroundings of all animals but that in another sense the surroundings of a single animal are different from those of any other animal.”

“For the present it is enough to note that the surroundings of any animal include other animals as well as the plants and the nonliving things. The format per are just as much parts of its environment as the inanimate parts. For any animals needs to distinguish not only the substances and objects of its material environment but also the other animals and the differences between them. It cannons afford to confuse prey with predator, own-species with another species, or male with female.

“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.”

“This means that the surface of the earth, millions of years ago before life developed on it, was not an environment, properly speaking.”

“We might agree to call it a world, but it was not an environment.”

“The mutuality of animal and environment is not implied by physics and the physical sciences. The basic concepts of space, time, matter, and energy do not lead naturally to the organism-environment concept or to the concept of a species and its habitat. Instead, they seem to lead to the idea of an animal as a extremely complex object of the physical world. The animal is thought of as a highly organized part of the physical world but still a part and still an object. This way of thinking neglects the fact that the animal-object is surrounded in a special way, that an environment is ambient for a living object in a different way from the way that a set of objects is ambient for a physical object. The term physical environment is, therefore, apt to get us mixed up, and it will usually be avoided in this book.”

“Every animal is, in some degree at least, a perceived and a behaved. It is sentient and animate, to use old-fashioned terms. It is a perceiver of the environment and a behaved in the environment. But this is not to say that it perceives the world of physics and behaves in the space and term of physics.”

“The size-level at which the environment exists is the intermediate one that is measured in millimeters and meters. The ordinary familiar things of the earth are of this size - actually a narrow band of size relative to the far extremes.”

“Within the intermediate band of terrestrial sizes, the environment of animals and men is itself structure at various levels of size. At the level of kilometers, the earth is shaped by mountains and hills. At the level of meters, it is formed by boulders and cliffs and canyons, and also by trees. It is still more finely structured at the level of millimeters by pebbles and crystals and particles of soil, and also by leaves and grass blades and plant cells. All these things are structural units of the terrestrial environment, what we loosely call the forms or shapes of our familiar world.”

“Now, with respect to these unites, an essential point of theory must be emphasized. The smaller units are embedded in the larger units by what I will call nesting.”

“There are forms within forms both up and down the scale of size. Units are nested within larger units. Things are components of other things. They would constitute a hierarchy except that this hierarchy is not categorical but full of transitions and overlaps. Hence, for the terrestrial environment, there is no special proper unit in terms of which it can be analyzed once and for all. There are n atomic units of the world considered as an environment. Instead, there are subordinate and superordinate units. The unit you choose for describing the environment depends on the level of the environment you choose to describe.”

“The size-levels of the world emphasized by modern physics, the atomic and the cosmic, are inappropriate for the psychologist. We are concerned here with things at the ecological level, with the habitat of animals and men, because we all behave with respect to things we can look at and feel, or smell and taste, and events we can listen to.”

“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.”

“And the ground itself is structure at various levels of metric size, these units being nested within ont another. The fact to be noted now, since it is important for the theory of perspective in Part II, is that these unites tend to be repeated over the whole surface of the earth.”

“These natural units are not, of course, perfectly uniform like the man-made tiles of a pavement. Nevertheless, even if their repetition is not metrically regular, it is stochastically regular, that is to say, regular in a probabilistic way. In short, the components of the ground do not get smaller one goes north, for instance. They tend to be evenly space; and if they are scattered they tend to be evenly scattered.”

“Another difference between the environment to be described and the world of physics is in the temporal scale of the process and events we choose to consider.”

“The changes that are perceived, those on which acts of behavior depend, are neither extremely slow nor extremely rapid.”

“The same thing holds for frequencies as for durations.”

“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.”

“The flow of abstract empty time, however useful this concept may be to the physicist, has no reality for an animal. We perceive no time but processes, changes, sequences, or so I shall assume.”

“The human awareness of clock-time, socialized time, is another matter.”

“Just as physical reality has structure at all levels of metric size, so it has structure at all levels of metric duration.”

“And once more it is important to realize that smaller units are nested within larger units. There are Events within events, as there are forms within forms, up to the yearly shirt of the path of the sun across the sky and down to the breaking of a twig. And hence there are no elementary units of temporal structure. You can describe the events of the environment at various levels.”

“The acts of animals themselves, like the events of the environment they perceived, can be described at various levels, as subordinate and superordinate acts. And the duration of animals acts is comparable to the duration of environmental events There are no elementary atomic responses.”

“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 men persistence over a day, a year, or a millennium. Almost nothing is forever permanent; nothing is immutable or mutable. So it is better to speak of persistence under change.”

“The abstract notion of invariance and variance in mathematics is related to what is meant by persistence and change in the environment. There are variants and invariants in any transformation, constants and variable. Some properties are conserved and others not conserved.”

“The persistence of the geometrical layout of the environment depends in part on the kind of substance composing it and its rigidity or resistance to deformation.”

“When we speak of the permanent layout of the environment,therefore, we refer mainly to the solid substances. The liquids of the world, the streams and oceans, are shaped by the solids, an as for the gaseous matter of the world, the air, it 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 physics calls it a mere change of state. Both assertions are correct, but the former is more relevant to the behavior of animals and children.”

“Physics has sometimes been take to imply that when a liquid mass has evaporated and the substance has been wholly dispersed in the air, or when an object has been consumed by fire, nothing has really gone out of existence. But this is an error.”

“Even if terrestrial matter cannot be annihilated, a resistant light-reflecting surface can, and this is what counts for perception.”

“Going out of existence, cessation or destruction, it S a kind of environmental event and one that is extremely important to perceive.”

“When something is burned up, or dissolved, or shattered, it disappears. But it disappears in special ways that have recently been investigated at Cornell (Gibson, 1968a). It does not disappear in the way that a thing does when it becomes hidden or goes around a corner. Instead, the form of the object may be optically dispersed or dissipated, in the manner of smoke.”

“A wholly invariant environment, unchanging in all parts and motionless, would've be completely rigid and obviously would no longer be an environment. In fact, there would be neither animals nor plants.”

“At the other extreme, an environment that was changing in all parts and was wholly variant, consistent get only swirling clouds of matter, would also not be an environment.”

“In both extreme cases there would be space, time, matter, and energy, but there would be no habitat.”

“Our failure to understand the concurrence of persistence and change that the ecological level is probably connected with an old idea - the atomic theory of persistence and change, which asserts that what persists in the world are atoms and what changes in the world are the positions of atoms, or their arrangement. This is still an influential assumption in modern physics and chemistry, although it goes back to Democritus and the Greek thinking who followed him.”

“The motions of things in the environment are of a different order from the motions of bodies in space.”

“Events on earth begin and end abruptly instead of being continuous. Pure velocity and acceleration, either linear or angular, are rarely observable except in machines. And there are very few ideal elastic bodies except for billiard balls.”

“The terrestrial world is mostly made of surfaces, not of baddies in space. And these surfaces often flow or undergo stretching, squeezing, bending, and breaking in ways of enormous mechanical complexity.”

“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 change in the layout rather than motions in the usual meaning of the term.”

“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.”