The emotional machine

It's interesting that we're basing the magic machine on something we don't understand. What is the importance of emotions in intelligence?

Emotions seem to do two things. One is that they modulate our behavior; the way we act varies according to how we feel about it. You can do the same job in many different ways: You can walk forward angrily or you can walk forward cheerfully. Mostly, [emotions are] the things that make the world mean something to us. They provide the value by which we measure things. If you don't have a means of measuring how your actions upon the world work out, and whether they're good or bad, you can never learn from them.

Emotions are what ground and connect us to the world. And yet most attempts at making artificial intelligence have assumed that the machine would just be intelligent anyway -- for example, that you might be able to make a computer that can speak English, but it won't actually have anything that it wants to say. But I think it has to want to say something. Otherwise it's just going to sit there. Emotions are what make us want and need things.

How would you build emotions in machines?

That's the tricky question.

With Creatures, you demonstrated that in some way, it is possible.

In some way. Emotions come at various levels. Something like fear is relatively easy to understand, whereas something like greed or embarrassment is a very subtle and sophisticated process. But the way things like fear, and sex drive, and maybe even loneliness get represented in the brain is perhaps fairly straightforward. The clever thing is how we recognize whether to be fearful.

In Creatures, I did it the simplest possible way. I just represented the mental state as a chemical state, which they are in us, too. Even when we fall in love there are particular chemicals associated with how much we feel like we're in love. It doesn't mean that love is nothing but a chemical, because all the complicated bits are the bits that allow us to realize that we are falling in love. But sooner or later it gets represented as a chemical. Changes in the levels of chemicals are partly what controls the way we learn and the way we measure whether what we've done is good or bad.

What ended up happening in Creatures? Did they express emotions?

It's hard to separate what they actually did from the things people imbued them with. Because it's a computer game, I deliberately made it easy for people to anthropomorphize and care about their creatures. That was the point. Sometimes people read more into it than they perhaps should. But then again that's probably true about their pet dog as well. Or maybe even their children.

But it was the emotions of people that really struck me. The first time I really noticed this was when one of my creatures fell in love with the other, or at least they became sexually attracted. There was a kind of love chase going on in the virtual world. My mother was watching this and then the program crashed. And my mom cried. I figured that I must be getting somewhere if I could make my mom cry.

So were you controlling them?

No, not at all.

You created them and then this just happened?

The important thing is that nothing inside the computer program knows what it is to be a creature. What I programmed into the computer were the rules of how to be a nerve cell and how to be a chemical reaction and how to be a gene. Then I built this huge network full of nerve cells and chemical reactions and genes, out of which the behavior of the creatures emerges. So the behavior of the creatures isn't programmed into the computer at all. That network of things can learn.

People grew to really care about these creatures, but one guy decided to torture them.

Oh, yes, Anti-norn.

What did he do exactly and what did it prove?

He set up a Web site -- it's still running, I think -- entirely devoted to torturing my poor creatures. I've never been able to make up my mind whether there's something wrong with him or whether he has a point to make. I get the feeling he does it tongue-in-cheek. The Creatures community ostracized him. He even got death threats. Somehow or other they thought my creatures were more valuable than his life.

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