What does it mean for cognition to be embodied?

In a classic demonstration of the remarkable plasticity of the brain, subjects were asked to wear special goggles that inverted the field of vision. At first, the subjects had difficulty functioning in a world that seemed upside down. They could soon function normally, however. They eventually even lost the feeling that they were seeing the world upside down -- until the goggles were removed!

Suppose that today's video game technology continues to improve until we can wear goggles and headphones that let us enter a richly detailed, highly believable, interactive virtual reality. As an experiment, suppose that a subject spends a long period immersed in a virtual reality where basic elements are gradually made to differ from what we consensually call the real world.

The virtual reality diverges incrementally until it eventually has nothing in common with the outside world. The modifications are so gradual and so consistently applied that the subject's brain adapts perfectly.

This is a little like the story of the man who decides to rename everything one object at a time. First he calls a 'tree' a 'dog', the next day he changes 'table' to 'door', and so on, until he eventually forgets the conventional names for things and his speech becomes nonsense to everyone but himself. In the same way, the virtual world might seem normal to the subject who has gradually adapted to it, but to us it would seem like a bizarre stream of arbitrary sounds and colors.

The brain is an organ that is exquisitely capable of discovering threads of consistency. It detects probabilities based on accumulated interactivity with sense organs and the nervous system as a whole.

The brain is so adept at detecting probabilities that we are generally unaware of its activity. We easily forget that the mind does not actually interact with the environment, but rather that it is perfectly encapsulated within the nervous system. We feel certain that we can see the outside world, but in fact our brains are only piecing together a flow of events taking place in our retinal cells and then making predictions based on those events. Our skin is the absolute boundary of our reality, the outer limit of the cosmos. We are our bodies, nothing more and nothing less.

The brain links together patterns of events taking place in our sense organs with such ease and alacrity that we have the conviction that the furniture of our consciousness is solid and separate from ourselves. We feel that we are observers watching the "movie of our lives," and we feel that we will outlast this movie because we are separate from it. We have a sense that the observer is real and permanent, even though the movie may not be.

This illusion is so strong that it seems hard to imagine how any self-governing system could work without having a central control that processes incoming data according to preconceived rules and then sends out commands in response. A different approach has actually been demonstrated in robotics, however.

What does it mean for control to be embodied rather than centralized? How can the paradox of the unending cascade of nested, self-referential observers within observers be solved for self-evolving systems?

The residue from the Cartesian view entices us to think that the brain contains an internal representation of the world that is somehow encoded within the brain's neural nets. Is that truly how the brain works? Is there actually a direct inner codification of experience? Could that inner codification -- the data that somehow makes up the essence of our minds -- someday be translated and copied to a different medium or to another brain?

Many people tacitly believe that a mind could in fact be copied from one brain to another if sufficiently advanced technology existed. That silent assumption exposes a Cartesian instinct. Such an assumption is flawed categorically, not technologically, because the entire viewpoint ignores the question of embodiment. It mistakenly sees the mind as being something greater or different than the accumulated interaction of a particular nervous system with other parts of a particular body.

The Cartesian instinct also underlies the hope of someday creating a mechanical intelligence that will approximate human intelligence. Non-mechanical, self-evolving systems will someday be created that will evince a kind of intelligence, but it will not be human intelligence unless it experiences a childhood in a human body.

The classic essay by T. Nagel, "What is it like to be a bat?" is an interesting discussion of the problem of communication between minds with different embodiments.

Michael Webb, 2000

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