Tag Archives: James Gibson

Reconciling Direct Realism?

Sometimes I sit in class and think about the nature of perception and reality. That sounds cliche, but I often find myself wondering whether I am really perceiving the professor as they give a lecture. What am I looking at? Am I merely perceiving representations, or ideas, in my head, or am I really looking at the external world? How can I reconcile the fact that visual information from the environment must be filtered through my nervous system before it is perceived with the sensation that I am directly looking at the world. On one hand, the representational theory of perception makes sense because it seems like there is always going to be this “gap” between my perception and reality, mediated through my sensory organs. On the other hand, it makes evolutionary sense that animals would develop a direct perceptual system in order to save cognitive resources. “Perception is cheap, representation is expensive.”

So what am I looking at when I perceive the world? Ideas in my head or real objects? James Gibson proposed a solution that he thought solved these dualistic paradoxes when he came up with the concept of the ambient optic array. Light is bouncing all around the environment, reflecting information about surfaces and textures, eventually settling into invariant “visual angles”. It is the information in this ambient optic array that we perceive. We don’t perceive the world. We don’t perceive representations in our head, projected onto a Cartesian theater. We directly pickup information from the invariant visual angles of light in the ambient optic array.

This is a mind/body/world system. It embedded and embodied. It is confusing to talk about sense-data stimulating the retina, and the brain “perceiving” this data, as if it was projected onto our cortex and the mind just mysteriously “reads” the data. This leads to conceptual muddles such as mind/body dualism and the representational theory of perception. Gibson thought it made more sense to talk about a ecologically embedded perceptual system picking up information directly from the environment. The distinction between this information pickup and the representational theory of perception is subtle. The difference lies in the fact that with the representational theory there is this impossible divide between between “internal” world of the mind and the “external” physical world. Somehow information crosses this metaphysical gap. Gibson thought it was much more parsimonious and evolutionarily sound to talk about perception in terms of direct pickup by a holistic agent in the environment. The information in the ambient optic array is structurally isomorphic to the firings of the nervous system, which is embedded in a whole body, capable of moving about in the world. By utilizing this ecological approach to perception, Gibson was able to drop the conceptual muddle of a “mind” perceiving ideas driven by the sense organs, but rather, a Self perceiving the environment through invariant structures in the light reflected in the environment. This is why the phenomenology of perception always puts the environment “out there”, in the world, as opposed to “inside” the internal chambers of the mind.

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The Environment Of One Observer and All Observers

In The Ecological Approach to Visual Perception James Gibson poses the following question:

The essence of an environment is that it surrounds an individual…the term surroundings is nevertheless vague, and this vagueness has encouraged confusion of thought. One such is the question of how the surroundings of a single animal can also be the surroundings of all animals. If it is assumed that no two observers can be at the same place at the same time, then no two observers ever have the same surroundings. Hence, the environment of each observer is “private,” that is unique.

So, how does Gibson resolve such a philosophical “puzzle”? He first notes that one can consider the layout of the surrounding surfaces in terms of a stationary point of observation, or one can consider the surrounding surfaces in terms of a moving point of observation. This latter consideration is much more useful because animals typically move about. So, for Gibson, “the available paths of locomotion in a medium constitute the set of all possible points of observation.”

Thus, all animals have an equal opportunity to explore the “persisting substantial layout” of the environment and in this way it “surrounds all observers in the same way that it surrounds a single observer.” By reconceptualizing visual perception in ecological terms, Gibson is able to cast off the ancient tradition of treating observers as standing “at the center of his or her private world.”

For Gibson, this fact of a moving point of observation is central to his approach to perception and its implications are “far-reaching”.

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Perception versus Representation

cartesian mind

The world is it’s own best model…why? We can put the answer in another slogan that [AI researcher] Brooks would probably like: Perception is cheap, representation expensive. Such a slogan might surprise many AI workers, who are acutely aware of how difficult pattern recognition can be. But the point is that good enough perception is cheaper than good enough representation-where that means “good enough” to avoid serious errors. The trouble with representation is that, to be good enough, it must be relatively complete and relatively up to date, both of which are costly in a dynamic environment. Perception, by contrast, can remain happily ad hoc, dealing with concrete questions only as they arise. To take a homely example, it would be silly, for most purposes, to try and keep track of what shelf everything in the refrigerator is currently on, if and when you want something, just look.

This quotation is from chapter nine of John Haugeland’s essays in the metaphysics of the mind, Having Thought. In the chapter, Haugeland argues against the “interrelationist” account of the mind and the body, which accepts the premise:

that the mental, or at any rate the cognitive”, has some essential feature, such as intentionality or normativity, and then argue that this feature is impossible except through participation in some supra-individual network of relations.

interrelationist arguments are holistic in the specific sense that they take cognitive phenomena to be members of some class phenomena, each of which has its relevant character only by virtue of its determinate relations to the others-that relevant character being, in effect, nothing other than its “place” in the larger pattern or whole.

As a competing theoretical framework, Haugeland offer’s what he calls the “intimacy of the mind’s embodiment and embeddedness in the world…[with the] term “intimacy” suggesting more than just necessary interrelation or interdependence but a kind of commingling or integralness.”

This embodiment relates to my earlier entry on the MIT Cog project, which is following the general thesis outlined by Haugeland, which is that intelligence does not depend on a “furniture of information” or “complex symbol structure that are, in many respects, just like the contents of the traditional Cartesian mind.”, but rather, on the “concrete details of the agent’s embodiment and worldly situation”.

This embodied and embedded approach to perception has probably been most controversially put forward by psychologist James J. Gibson. Haugeland quotes him as follows:

the words animal and environment make an inseparable pair. Each term implies the other. No animal could exist without an environment surrounding it. Equally, although not so obvious, an environment implies an animal(or at least an organism) to be surrounded. This means that the surface of the earth, millions of years before life developed on it, was not an environment, properly speaking.

Thus, in this sense, Haugeland says that we can understand animals(including humans) as “perceivers” if we consider than “inseparably related to an environment, which is itself understood in terms appropriate to that animal”.

So for humans, in order to understand perception, we must understand our complexly relative relationship to the environment, which necessarily implies our dynamic socialization schemas. Furthermore, Gibson claims that in order to understand this perception of the environment, we must take into account the affordances of the environment, or what it offers to the animal. Thus, “the central question for the theory of affordances is not whether they exist and are real but whether information is available in ambient light for perceiving them”.

This perception of affordances puts the first quotation of this post in context. The world is it’s own best model and our perception of it is in relative(embodied and embedded) terms with the environment.

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