Why no brain-in-a-vat

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.


2 thoughts on “Why no brain-in-a-vat

  1. Lyndon

    I was thinking about the fielder example before as well. And let me give a counter example. Let us tell some similar story about navigating a car. As we drive, we take in the image and idea of a slow moving car in front of us, and deftly pass it. Obvious our dynamics there will be a bit different, but say that something similar to the fielder situation is happening. But let us now take a newer example. A Google Car performs the same maneuver. I have only rudimentary understanding of how the Google Car performs such, but it sounds like there is some similarities. Something like perceiving and representing an object ahead and then engaging car maneuvers to keep its own car so far away from the slow moving object until it passes it.

    I see no reason for describing either problem solving solution as embodied, nor do I understand what that descriptor is adding to the mechanisms that are in use. Humans, like Google Cars, do constant calculations based on the constant bombardment of perceptual information. If classical cognition was ignoring this, then yes it was wrong. I assume Google is using a similar strategy because it is both efficient and cost effective (in a processing sense).

    Furthermore, there is goal like behavior to the Google Car, somebody tells it to go from point A to point B. The Google Car passes the other car because of this goal like structure. This gets to some of the other issues with embodied cognition, namely the idea of evolutionary design of behavior, and the understanding of cognition as part of the other desires and goals of the organism. But like the Google Car, I read “goal like behavior” as simply another factoid of the brain, perhaps evolutionarily induced.

    Think of baby turtles who have drives upon hatching that push them to the sea. They then use their other pre-wired brain/body structures of movement and certain perceptions to move towards the sea. However such is structured, I am fine with that being a useful, helpful description about the turtle brain and about why it is structured the way it is, including in the cognitive activity that ensues. In the end, it is still just a processing system. In this case pre-programmed to engage in an immediate goal like behavior along with fairly well-tuned environmental perceptions and body processing procedures upon birth (as opposed to us mammals).

    1. JKwasniak Post author

      I have a bit of trouble with the classic cognition (as you do with embodiment). I am sure that sort of manipulate symbols type thinking does occur a bit. However, I am not a great believer in the computer metaphor for the brain. Signals within the brain do not tend to be discrete while they are being processed, in other words the brain is not really a digital system, despite the fire-or-don’t-fire idea of neurons. The operations of the brain do not tend to by stepwise, so they are not very algorithm like. Certainly there are no stored algorithms in the brain other than the consciously learned and used semantic and mathematical ones. The brain is massively parallel, from a computer viewpoint almost unbelievably so – the separate loops can be counted in the billions. So it appears to be more akin to an analog than a digital computer, if it must be thought of as a kind of computer. And of course I mentioned that the brain has task related abilities not general computational ones. The brain does not seem to have an input-process-reactive output path but instead an output-predict input-compare to input-adjust output. Things seem to start with a goal, aim or intent rather than a reaction to the environment. As I do not find the classic cognition model of a computer-like brain believable (except in minor ways) I do not resist the embodied model which does not assume conventional computation and makes good sense to me.


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