Is the Brain a Computer?Philosophy of Mind

BRENT SILBYUnlimited (UPT)

Is the brain a computer?

How does a computer work?

Two types of computer…1. Sequential digital processing2. Parallel processing

Sequential Digital Processing

Computers used to be single, sequential processorsThey performed only one task at a time. They appear to be multitaskingbecause they perform tasks extremely quickly.

To solve a problem, a sequential processor will treat the problem asa number of steps that are followed in sequence.

Dual core CPUs can perform 2 tasks at once, so they are faster

Are brains (or minds) sequential processors?

We do operate in a sequential manner. We calculate math problemsin a step by step manner.

Even our communication is based on a sequential system. Sentencescan be broken up into symbols, which are interpreted according to a sequence of rules.

Problem with Brain as a sequential processor

Neurons are incredibly slow compared to the switches contained ona CPU.

A CPU switch can flip/flop from 0 to 1 in about 1 hundred thousandmillionth of a second--VERY FAST

A neuron takes about a thousandth of a second to flip in response toinput--VERY SLOW

So a brain neuron takes 100 million times longer to do the samething a CPU switch can do.

THE 100 STEP LIMITATION

* Suppose that the brain works by following a sequential programlike a computer (i.e. by following one instruction at a time in aprogram)

* Because of the speed of neurons, the maximum number of instructionsa brain can carry out in a 10th of a second is 100.

* It takes only about a 10th of a second for the brain to extract themeaning from a sentence.

* It follows that if the brain is following a sequence of instructions,then it would only take a program of 100 instructions for the brainto gain meaning from a sentence.

BUT, This is an incredibly small number of instructions in a program.

A simple PACMAN game requires a program of1000 lines of instructions.

Current Artificial Intelligence programs contain over 1,000,000lines of code (or instructions).

We must conclude that whatever the brain does, it is not followinga list of instructions (or program) one step at a time.

How can the brain do everything it does so quickly?

Parallel Processing !

A Parallel Processor is a type of computer that carries out manyinstructions simultaneously.

Imagine that I have 40 jars, and hidden underneath 1 of those jarsis a $20 note.

A sequential processor would search for the note by checkingone jar at a time. This is how a search engine works.

A parallel processor would would check under every jar at the sametime. This is very fast and efficient.

Its like having 40 single processors all working at the same time.

* There is no real difference between what a sequential processor and a parallel processor can do.

A sequential processor can do everything that a parallel processor cando. It just breaks the process down into a step by step, one instructionat a time procedure.

If this is true, is it possible to build a sequential computer that cansimulate the brain? [discuss]

Perhaps, but given the number of connections in the brain, it wouldtake a modern computer several years to do what a brain does in justone second !

How brains and computers remember things…

* Memory is vital to computers* Memory is also vital to brains

* In a computer, bits of information are stored in specific locationseither in RAM, CD, DVD, Flash, or Hard-drive.

These locations have specific names. Information can be retrievedwhen the program looks up a certain name and checks the contentof that location.

In a brain, there are no such locations.

You cannot point to a specific place in the brain and say“this is my memory from 10pm last Saturday night”.

The brain is not like a video camera, and does not record informationcompletely and store it in certain places.

When events happen, they have an impact on the neural structure ofthe brain.

For example, at a party on Saturday night at 10pm this happened:* A song called “Show me love” was playing* Someone spilled beer on me* I could smell hot chips

Each of these things effected my brain and set up a connectedneural structure.

* The song set up a neural pattern in my auditory system* The wet beer set up a pattern in another sensory system* The smell of hot chips set up another pattern

These patterns are all connected through a neural link.

Now, when I smell hot chips, that will re-activate the previousneural pattern, which is connected to the others which are alsore-activated.

That’s why when I smell hot chips, it makes me think of the song“Show me love”. The memory of that event is stored everywherein the brain.

BUT,The memory is not permanent.

The neural connections will weaken if not used, and the memorycan fade.

On the other hand, if the memory *is* used, then the memory willstrengthen.

WARNING! Memory will become unreliable with time. Wheneverit is retrieved, there is risk that it will be associated with other eventssince they create connected neural patterns.

Human memory is extremely unreliable.

e.g. of violent crime victim in courte.g. of crime victims testifying years after event took place

Despite its unreliability, human memory allows human creativity

This is because of the way certain ideas trigger memories, andconnections with other events.

Human brains are associative engines. Its all about buildingassociations.

Computer software is implemented on sequential hardware

The mind is implemented in the parallel processing, connectionist brain network

But the mind doesn’t feel like it’s a parallel processing, connectionistdevice.

Think about day-to-day experiences. It feels like our mind is adigital/sequential system.

WHY?

• The brain is a parallel processing computer, which is built froma connectionist network

• The mind is a sequential program, which is implemented upon thebrain’s parallel hardware.

This is possible through language !

Language is a sequential system that is installed on the connectionisthardware of the brain. It allows the brain to operate as a sequentialsystem.

So, is the brain a computer?

Yes, it’s a parallel processing connectionist device.

The mind is a sequential software that operates in the brain.It is installed slowly through the acquisition of language.

Now, the big question…

Can a brain be *conscious* without a mind? Or is a mind essentialfor consciousness? If so, then according to the above hypothesislanguage is essential for consciousness.

Powerpoint by BRENT SILBYwww.def-logic.com

Produced at UPTChristchurch, New Zealand

www.unlimited.school.nz