The Brain as a Computer

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At my first meeting with vision scientist and neurobiologist, Colin Blakemore, I asked him if the brain is like a computer and his response, “The brain is a computer,” made me smile. He had turned my metaphor into the thing itself that I was trying to represent.

Later I conducted some research and looked into the etymology of the word ‘computer.’ The term came into use in the 17th Century to mean a human being who “computes.” It is formed from the Latin verb computare, meaning ‘to count, sum up; reckon’.

In Chinese, on the other hand, the etymology of the word seems to have originated from the commonalities between the brain and the modern day computer. The Chinese word for computer, 電腦 translated literally is: “electric brain.”

Perhaps the boundary between human and machine is not so distinct after all?

At our next meeting at his office at the Centre for the Study of the Senses, University of London, I asked Colin about the analogy of the brain as a computer, how useful this is and where the limits lie.

He began by exploring the definition of what a computer is:

If we justify the computer as something that takes data in, in some form, processes it, stores some of it, acts on the rest by controlling something or displaying it, then certainly the brain is a computer… but the mechanisms are quite different.

He went on to explain how when we look at a scene, we are able to extract meaning from it:

You’re looking at a building with a tree in front of it, you see and understand the whole building even though what you can really see are two half buildings with a tree cutting them in half. Nevertheless you never think of them in that way, you think of them as a building. So, we’re very good at filling in the missing information.

One dramatic difference between the brain and the computer is the rate in which information can be processed. The brain seems to also have very strict bottlenecks of information processing:

Typically, working memory – the things that we’re holding continuously as you move around the world for short periods of time… the content of working memory is very small, it’s a few tens of bits of information as opposed to the gigabytes of RAM on a computer. And yet the brain is being flooded with the same kind of rate of information input that computers are.

The limits of the capacity of our visual attention is also very small. Our brains therefore have to be selective:

One way that is achieved is through attention. It looks as though what goes into working memory is largely determined by what we are attending to… When we look at a scene, most of what’s going into our eyes is not being attended to.

Since much of the visual input into our eyes is not attended to, what then is the relationship between what our eyes receive and what we perceive?