In Chapter 1, Gibson identified the animal and it's environment as the two mutually defining parts of an ecological system. In Chapter 2, he developed a vocabulary for describing an environment (as opposed to the physical world). Now, in Chapter 3, he will use that vocabulary to identify that the environment of an animal is meaningful, literally full of meaning, and this will mean that meaning is there to be discovered, rather than constructed (as in every theory of perception so far).
Sabrina also blogged this chapter here.
The first thing he does is continue to develop the vocabulary for describing the environment at the ecological scale. We have the triad of medium, substance, and surfaces, and surfaces are what will do the main work of creating information, so they will be what are perceived. We need ways to talk about the layout of surfaces in the environment.
He begins with the ground; the literal surface of the earth that will serve as the reference for the layout of all other surfaces. (This is a classic Gibson sneaky move; pointing out an obvious feature of the environment that will play a key role in making perception possible without, at this point, huge fanfare.) The ground is, on average level (perpendicular to gravity, that other ubiquitous feature of the environment that provides a frame of reference). Surfaces are then laid out along the ground.
An open environment is just the ground. An enclosure is a layout of surfaces attached to the ground that surrounds the medium to some degree (100% enclosure is a rare limiting case. partial enclosure is more common).
Some surfaces are laid out such that they are completely surrounded by the medium; these are detached objects. An attached object is only partly surrounded by the medium. Objects can be counted, unlike substances or the ground. Attachment, like all things, is relative to the animal-environment system being discussed (a tree is attached relative to animals but detached relative to itself). A hollow object is an object that is also an enclosure. The boundaries between these categories are flexible and relative to the system being examined. Gibson also names a few specific examples of objects and common surface layouts.
Finally a place is a location in an environment (vs. a point in space), and the habitat of an animal (one sense of the word environment) is made up of places. Environments change via changes in the overall layout of surfaces.
Affordances
The notion of affordances is introduced (although we won't get into the details till Chapter 8). But they show up here because out of all the places and surface layouts in the environment, some will be of particular relevance to particular organisms and when talking about perception, we need to focus on those (rather than the large general set). Another ecological move - be specific, not general. In this way, Gibson is going to describe how perceivable surface layouts can create a environment that is meaningful to the organism in question.
Animals locomote in various ways. Surface layouts can offer openings onto paths, but also obstacles, or more generally, barriers. You usually cannot see through barriers, but there are edge cases (windows are barriers you can see through; clouds don't let you see through them but aren't barriers; again, these categories are fluid and relative). There are brinks you can fall off, but if they are small enough they might merely be steps (size relative to the organism, of course). Some surface layouts create enclosures animals use as shelters. When animals build things, they are changing surface layouts to allow or disallow behaviours (creating paths, blocking entrances, etc).
There are other things besides surfaces. Water is sometimes a surface but is mostly a substance or a medium, and it has all kinds of meanings for organisms. Fire is an event, but it affords all sorts of things as well; these affordances of water and fire can be good (drinking, warming) or bad (drowning, burning), and these can be co-occurring and need to be balanced by the activity of the animal.
Objects (that particular class of surface layouts) can afford grasping, carrying, throwing and much more. A special class of objects can be called tools - they are "graspable, portable, manipulatable, and rigid" (pg 34). Tools extend what animals can do, but are not always part of the animal (which implies that the "boundary between the animal and the environment is not fixed at the surface of the skin but can shift" - hello, extended cognition). What is 'objective' and 'subjective' is not fixed (this will be a key part of affordances later).
A special class of detached objects are other animals which can be moved passively but also move themselves actively. Animals have a large range distinct characteristics, and can afford many things to an organism. Gibson spends no real time here, but simply notes that a good social psychology should also begin with what animals afford and how those are perceived (the topic of the rest of the book).
One final class of objects are the weird ones we will deal with at the end - displays, surfaces treated to look like something else. These are not a base case for perception, so we need to wait to deal with them.
Environments of One vs All Observers
When Gibson defined the environment, he noted that it contains two ways of talking in the same word. An environment can surround an individual, but can also surround all the individuals in the area. Because no two individuals can be in the same place at the same time, it seems like each 'environment' is private and personal, i.e. not the same as that of the other animals. Gibson wants to resolve this as he promised.
The solution is that animals move. The environment is a layout of surfaces, and you can consider this from a stationary point of observation (which leads to the problem). But the more ecological case is to consider it relative to the trajectory for a moving point of observation. Any animal in an environment can move to be in the same place as another animal at a different time, and to the extent the surface layout is stable, they will perceive the same environment. The environment for all observers can be explored by any specific observer, and all those observers can experience any viewpoint on that environment. The environment is not private to the individual, but publically explorable by all individuals.
I'll note again that Baggs & Chemero (2020) have proposed the solution to the two senses of environment' problem is to simply embrace it, and distinguish between the habitat of the species and the umwelt of the individual. This might be ok, but it occurs to me that it is actually very important for Gibson's approach that the solution is not to allow the distinction to hold up. In sports, for example, researchers talk about individuals working with team mates via shared mental models they have to create privately that hopefully have the same contents, vs. working together via the perception of a shared field of affordances in an environment. The former works in Gibson's account, but may not in Baggs & Chemero's. I will dig into this in more detail in the future.
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