March 6, 2011 80 Comments
I don’t want to get technical right now, but I thought I’d write a little introduction to what I’m actually trying to do in my Grandroids project. Or perhaps what I’m not trying to do. For instance, a few people have asked me whether I’ll be using neural networks, and yes, I will be, but very probably not of the kind you’re expecting.
When I wrote Creatures I had to solve some fairly tricky problems that few people had thought much about before. Neural networks have been around for a long time, but they’re generally used in very stylized contexts, to recognize and classify patterns. Trying to create a creature that can interact with the world in real-time and in a natural way is a very different matter. For example, a number of researchers have used what are called randomly recurrent networks to evolve simple creatures that can live in specialized environments, but mine was a rather different problem. I wanted people to care about their norns and have some fun interacting with them. I didn’t expect people to sit around passively watching hundreds of successive generations of norns blundering around the landscape, in the hope that one would finally evolve the ability not to bump into things.
Norns had to learn during their own lifetimes, and they had to do so while they were actively living out their lives, not during a special training session. They also had to learn in a fairly realistic manner in a rich environment. They needed short- and long-term memories for this, and mechanisms to ensure that they didn’t waste neural real-estate on things that later would turn out not to be worth knowing. And they needed instincts to get them started, which was a bit of a problem because this instinct mechanism still had to work, even if the brains of later generations of norns had evolved beyond recognition. All of these were tricky challenges and it required a little ingenuity to make an artificial brain that was up to the task.
So at one level I was reasonably happy with what I’d developed, even though norns are not exactly the brightest sparks on the planet. At least it worked, and I hadn’t spent five years working for nothing. But at another level I was embarrassed and deeply frustrated. Norns learn, they generalize from their past to help them deal with novel situations, and they react intelligently to stimuli. BUT THEY DON’T THINK.
It may not be immediately obvious what the difference is between thinking and reacting, because we’re rarely aware of ourselves when we’re not thinking and yet at the same time we don’t necessarily pay much attention to our thoughts. In fact the idea that animals have thoughts at all (with the notable exception of us, of course, because we all know how special we are) became something of a taboo concept in psychology. Behaviorism started with the fairly defensible observation that we can’t directly study mental states, and so we should focus our attention solely on the inputs and outputs. We should think of the brain as a black box that somehow connects inputs (stimuli) with outputs (actions), and pay no attention to intention, because that was hidden from us. The problem was that this led to a kind of dogma that still exists to some extent today, especially in behavioral psychology. Just because we can’t see animals’ intentions and other mental states, this doesn’t mean they don’t have any, and yet many psychological and neurological models have been designed on this very assumption. Including the vast bulk of neural networks.
But that’s not what it’s like inside my head, and I’m sure you feel the same way about yours. I don’t sit here passively waiting for a stimulus to arrive, and then just react to it automatically, on the basis of a learned reflex. Sometimes I do, but not always by any means. Most of the time I have thoughts going through my mind. I’m watching what’s going on and trying to interpret it in the light of the present context. I’m worrying about things, wondering about things, making plans, exploring possibilities, hoping for things, fearing things, daydreaming, inventing artificial brains…
Thinking is not reacting. A thought is not a learned reflex. But nor is it some kind of algorithm or logical deduction. This is another common misapprehension, both within AI and among the general public. Sometimes, thinking equates to reasoning, but not most of the time. How often do you actually form and test logical propositions in your head? About as often as you perform formal mathematics, probably. And yet artificial intelligence was founded largely on the assumption that thinking is reasoning, and reasoning is the logical application of knowledge. Computers are logical machines, and they were invented by extrapolation from what people (or rather mathematicians, which explains a lot) thought the human mind was like. That’s why we talk about a computer’s memory, instructions, rules, etc. But in truth there is no algorithm for thought.
So a thought is not a simple learned reflex, and it’s not a logical algorithm. But what is it? How do the neurons in the brain actually implement an idea or a hope? What is the physical manifestation of an expectation or a worry? Where does it store dreams? Why do we have dreams? These are some of the questions I’ve been asking myself for the past 15 years or so. And that’s what I want to explore in this project. Not blindly, I should add – it’s not like I’m sitting here today thinking how cool it will be to start coming up with ideas. I already have ideas; quite specific ones. There are gaps yet, but I’m confident enough to stick my neck out and say that I have a fair idea what I’m doing.
Explaining how my theories work and what that means for the design of neural networks that can think, are things that will take some explaining. But for now I just wanted to let you know the key element of this project. My new creatures will certainly be capable of evolving, but evolution is not what makes them intelligent and it’s not the focus of the game. They’ll certainly have neural network brains, but nothing you may have learned about neural networks is likely to help you imagine what they’re going to be like; in fact it may put you at a disadvantage! The central idea I’m exploring is mental imagery in its broadest sense – the ability for a virtual creature to visualize a state of the world that doesn’t actually exist at that moment. I think there are several important reasons why such a mechanism evolved, and this gives us clues about how it might be implemented. Incidentally, consciousness is one of the consequences. I’m not saying my creatures will be conscious in any meaningful way, just that without imagery consciousness is not possible. In fact without imagery a lot of the things that AI has been searching for are not possible.
So, in short, this is a project to implement imagination using virtual neurons. It’s a rather different way of thinking about artificial intelligence, I think, and it’s going to be a struggle to describe it, but from a user perspective I think it makes for creatures that you can genuinely engage with. When they look at you, there will hopefully be someone behind their eyes in a way that wasn’t true for norns.