Tag Archives: embodied

Why no brain-in-a-vat

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A comment on the previous blog asked for a discussion of embodied cognition. I will try to express why I find embodied cognition a more attractive model than classic cognition. My natural approach to living things is biological – I just think that way – and if something does not make much sense from a biological standpoint than I am suspicious.

So to start, why don’t all living things have brains? Brains seem to be confined to animals, organisms that move. This makes sense: to move an organism needs mechanisms for propulsion (muscles for example), mechanisms to sense the environment (eyes for example), and mechanisms for coordinating and planning movement (nervous systems). So we have motor neurons that activate muscles and sensory neurons that sample the environment and the two are connected in the simplest nervous systems. But all we have in this simple setup is reflexes and habituation. But if there are nets of inter-neurons between the motor and sensory ones then complex actions and thoughts are possible including learning, memory, a working model of reality, emotion, problem solving etc. (brains). In other words, I picture cognition as coming into being and then being honed by evolution as an integral part of the whole organism: its niche or way of life, its behaviour, its anatomy.

Did the evolutionary process give us a brain that is a general computer? Why would it? There tends to be a loss of anatomy/physiology when they are not particularly useful. For example, moles lost sight because their niche is without light; parasites can lose all functions except nutrition and reproduction. A general computer would be a costly organ so it would only be evolved if it were definitely useful.

Today science does not hold that there are exactly three dimensions but talks of 4, 11 ½, 37 etc. We can accept more than 3, believe there are more than 3, but we cannot put ourselves in more than 3 dimensions no matter how we try. Our brain is constructed to create a model of the world with 3 dimensions and that is that. Why? We sense our orientation, acceleration, balance from the semi-circular canals of the inner ear. There are 3 canals and they are at mutual right angles to each other – physical x,y,z planes are evident in this arrangement. The parts of the brain that do the cognitive processes to track orientation, acceleration and balance are built to use signals from the inner ear. It is not a general computing ability that could deal with the mathematics of any number of dimensions – no, it is a task-specific cognitive ability that only deals in 3 dimensions. I think that all our cognitive abilities are like this; they are very sophisticated in what they do but limited to tasks that are useful and matched to what the body and environment can supply.

Further, when evolutionary pressures are forcing new behaviours and reality modeling, new cognitive abilities are not created from scratch, because changes to old cognitive abilities are faster. They will win the race. Take time for example. Animal usually have circadian rhythms and often seasonal/tidal rhythms too. But to incorporate time into our model of reality would probably require a lot of change if done from scratch. However we already have an excellent system for incorporating space in our reality. The system of place cells, grid cells, border cells, heading cells etc. is elaborate. So we can just deal with time as if it was space. Many of these re-uses of old abilities can be seen in the metaphors that people use. A whole branch of embodiment is dedicated to identifying these metaphors used in our normal thinking.

This business of re-using one ability to serve other domains brings up the question of ‘grounding’. People often remark on the circularity of dictionaries. Each word is defined by other words. As we pile up metaphoric schemes each an elaboration and re-identification of elements of other metaphors, the situation appears circular and unsupported. But with a dictionary, what is needed is that a few primitive words are defined by pointing at the object. In the same way each pile of metaphors needs to be grounded in the body. There are primitive schemes that babies are born with or that they learn naturally as they learn to use their bodies. In other words all the cognitive abilities can be traced back to the nature of the body and environment.

There is one case where it can be proven that the cognition is embodied and not classic. When a fielder catches a fly ball, the path he runs is that of an embodied method and not a classic one. The fielder makes no calculation or predictions, he simply keeps running in such a way as to keep the image of the ball in the sky in a particular place. He will end up with the ball and his glove meeting along that image line. There are good write ups of this. (here)

By contrast, classical cognition is seen as isolated and independent from the body and environment, using algorithms to manipulate symbols and capable of running any algorithm (ie a general computer). It just does not ring true to me. I see the brain-in-a-vat as about as useful as a car engine in a washing machine. Why would anyone want a brain-in-a-vat? As a thought experiment to support skepticism it is so-so, because like many philosophical ideas it is concerned with Truth, capitalized. Whereas the brain is not aiming at truth but at appropriate behaviour. A heart can be kept alive on an isolated heart perfusion apparatus and it will beat away and pump a liquid – but to what purpose? Even robots need bodies to really think in a goal directed, real time, real place way and so they are fitted with motors, cameras, arms etc. Robots can be embodied.

 

Embodied thinking

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TalkingBrains has a posting, “Embodied or Symbolic? Who Cares?” (here). Greg Hickok is asking what exactly is the difference between embodied and symbolic cognition. He takes a nice example of a neurocomputation that is understood, the way a barn owl turns its head to a sound source. If you have not seen it before have a look at the link – it is well explained and easy to follow.

He asks:

Question: what do we call this kind of neural computation? Is it embodied? Certainly it takes advantage of body-specific features, the distance between the two ears (couldn’t work without that!) and I suppose we can talk of a certain “resonance” of the external world with neural activation. In that sense, it’s embodied. On the other hand, the network can be said to represent information in a neural code-the pattern of activity in network of cells-that no longer resembles the air pressure wave that gave rise to it. In fact, we can write a symbolic code to describe the computation of the network.

I think, however, that the example is a bit off the subject. Of course there are many examples in the brain of clear computations that could be presented in the form of a computer program or an algorithm for manipulating symbols. And it is generally assumed that the brain manipulates entities that are best called symbols: words, objects, concepts, places and the like. Even the brains great ability to work with metaphors is like substituting symbols in schemes that relate a number of symbols in a particular way. Symbols and their manipulation seems useful in understanding the brain. Symbols in the brain, of course, would always be metaphors for actual processes, but then the idea of a symbol is by its nature always a sort of metaphor standing in for whatever it is a symbol of.

But just because some, or a great many perhaps, processes in the brain can be pictured as manipulations of symbols, in ways akin to algorithms, this does not mean that the brain acts like a general computing device. Embodied cognition is quite clearly computation only in the sense of task specific processes and architecture and, not the actions of a general device. To be understood, the brain has to be seen as an integral part of the body. It is and does its part of what the body is and does. The cognitive abilities and facilities of the brain are the ones the body needs to function. If those abilities are sometimes used for arbitrary and abstract things like playing chess, this does not mean that they are not individually ‘grounded’ in the body’s requirements and limitations.

Just because some task could be done in a particular way, does not mean that it is done that way. The brain is what it is; metaphors can help us understand its workings or they can also stand in the way of understanding. They do not dictate the nature of the brain. We always should keep in mind that metaphors are somewhat limited tools.