As reported in my previous two blog entries How and Why do we have Culture?, and What do Aliens look like?, I've become involved in National Science Week, a major part of which has been structured around Big Questions. I've had some fun the last few days responding to some of the big questions - which are really good. Here are the questions and responses I've made so far:
When will people invent robots to fight in wars?
Could you create a robot with a mind of its own?
Can we invent a robot that will do everything for you?
Will the human brain ever be capable of understanding itself?
What actually is Intelligence? Do we understand it?
Is it possible that AI technology may get out of control?
Showing posts with label brain. Show all posts
Showing posts with label brain. Show all posts
Monday, March 10, 2008
Monday, February 06, 2006
On free will and noisy brains
Consider that humblest of automata: the room thermostat. It has a sensor (temperature) and an actuator (boiler on/off control) and some artificial intelligence, to decide whether to switch the boiler on - if the room is getting cold, or off - if the room is getting too warm. (If the thermostat has hysteresis the 'on' temperature will be different to the 'off' temperature - but that's not important here.)
I said that the theromstat's AI 'decides' whether to switch the boiler on or off, which implies that it has free will. Of course it doesn't, because its artificial intelligence is no more than a simple rule, 'if temperature <> 60 then switch boiler off', for example. So, depending on the temperature, what the thermostat decides is completely determined. With this simple deterministic rule the thermostat can't simply decide to switch the boiler off regardless of the temperature just for the hell of it.
Well all of that is true for 99.99..% of the time. But consider the situation when the temperature is poised on almost exactly the value at which the thermostat switches. The temperature is neither going up nor down but is balanced precariously at a value just a tiny fraction of a degree away from the switching value. Now what determines whether the thermostat will switch? The answer is noise. All electrical systems (actually all physical systems above absolute zero) are noisy. So, at any instant in time the noise will have the effect of adding or subtracting a tiny amount to the temperature value, either pushing it over the switching threshold, or not.
For 99.99..% of the time the thermostat is deterministic, but for the remaining 0.00..1% of the time it is stochastic: it 'decides' whether to switch the boiler on or off at random, i.e. 'just for the hell of it'.
But, I hear you say, that's not free will. It's just like tossing a coin. Well, maybe it is. But maybe that's what free will is.
Consider now that oldest of choices. Fight or flee. Most of the time, for most animals, there is no choice. The decision is easy: the other animal is bigger, so run away; or smaller, so let's fight; or it's bigger but we're trapped in a corner, so fight anyway. Just like the thermostat, most of the time the outcome is determined by the rules and the situation, or the environment.
But occasionally (and probably somewhat more often than in the thermostat case) the choices that present themselves are perfectly evenly balanced. But the animal still has to make a choice and quickly, for the consequences of dithering are clear: dither and most likely be killed. So, how does an animal make a snap decision whether to fight or flee, with perfectly balanced choices? The answer, surely, is that the animal needs to, metaphorically speaking, toss a coin. On these rare occasions its fate is decided stochastically and brains, like thermostats, are noisy. Thus it is, I contend, neural noise that will tip the brain into making a snap decision when all else is equal - the neural equivalent of tossing a coin.
This is why I think brains evolved to be noisy.
The long extinct ditherers probably had less noisy brains.
I said that the theromstat's AI 'decides' whether to switch the boiler on or off, which implies that it has free will. Of course it doesn't, because its artificial intelligence is no more than a simple rule, 'if temperature <> 60 then switch boiler off', for example. So, depending on the temperature, what the thermostat decides is completely determined. With this simple deterministic rule the thermostat can't simply decide to switch the boiler off regardless of the temperature just for the hell of it.
Well all of that is true for 99.99..% of the time. But consider the situation when the temperature is poised on almost exactly the value at which the thermostat switches. The temperature is neither going up nor down but is balanced precariously at a value just a tiny fraction of a degree away from the switching value. Now what determines whether the thermostat will switch? The answer is noise. All electrical systems (actually all physical systems above absolute zero) are noisy. So, at any instant in time the noise will have the effect of adding or subtracting a tiny amount to the temperature value, either pushing it over the switching threshold, or not.
For 99.99..% of the time the thermostat is deterministic, but for the remaining 0.00..1% of the time it is stochastic: it 'decides' whether to switch the boiler on or off at random, i.e. 'just for the hell of it'.
But, I hear you say, that's not free will. It's just like tossing a coin. Well, maybe it is. But maybe that's what free will is.
Consider now that oldest of choices. Fight or flee. Most of the time, for most animals, there is no choice. The decision is easy: the other animal is bigger, so run away; or smaller, so let's fight; or it's bigger but we're trapped in a corner, so fight anyway. Just like the thermostat, most of the time the outcome is determined by the rules and the situation, or the environment.
But occasionally (and probably somewhat more often than in the thermostat case) the choices that present themselves are perfectly evenly balanced. But the animal still has to make a choice and quickly, for the consequences of dithering are clear: dither and most likely be killed. So, how does an animal make a snap decision whether to fight or flee, with perfectly balanced choices? The answer, surely, is that the animal needs to, metaphorically speaking, toss a coin. On these rare occasions its fate is decided stochastically and brains, like thermostats, are noisy. Thus it is, I contend, neural noise that will tip the brain into making a snap decision when all else is equal - the neural equivalent of tossing a coin.
This is why I think brains evolved to be noisy.
The long extinct ditherers probably had less noisy brains.
Monday, January 23, 2006
On what brains are for
Just started reading Sue Blackmore's new book: Conversations on Consciousness. Great introduction - but I have stalled already on Q2 of the 1st conversation - Baars. He says "the primary function of the nervous system is to encode knowledge...".
Surely not.
Brains are control systems for bodies. Pretty amazing control systems of course, but control systems all the same. Bodies have sensors (senses) and actuators (muscles). In very simple animals the outputs from the senses are almost directly connected to the muscles, so that the animal always reacts reflexively to stimuli. More complex animals have more brain in between senses and muscles and so may deliberate before reacting. Of course even very complex animals still have reflexes - think of the classic reflex test on your knee.
Of course I accept entirely that complex brains do encode knowledge, probably in a multiplicity of ways some of which we can discern - like the apparent spatial mapping of images into the visual cortex - but many ways that are not (yet) at all understandable.
But that is not what they're for.
Surely not.
Brains are control systems for bodies. Pretty amazing control systems of course, but control systems all the same. Bodies have sensors (senses) and actuators (muscles). In very simple animals the outputs from the senses are almost directly connected to the muscles, so that the animal always reacts reflexively to stimuli. More complex animals have more brain in between senses and muscles and so may deliberate before reacting. Of course even very complex animals still have reflexes - think of the classic reflex test on your knee.
Of course I accept entirely that complex brains do encode knowledge, probably in a multiplicity of ways some of which we can discern - like the apparent spatial mapping of images into the visual cortex - but many ways that are not (yet) at all understandable.
But that is not what they're for.
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