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The Designer's Notebook: Numbers, Emotions, and Behavior
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The Designer's Notebook: Numbers, Emotions, and Behavior

January 27, 2009 Article Start Previous Page 3 of 3

Sometimes in a movie, you'll see a scene in which a woman has been frightened or angered by something her lover has done. She attacks him ineffectually, shouting abuse, but a moment later slumps weeping into his arms. Her initial fury dissipates almost immediately and she forgives him -- especially if the audience knows he wasn't really at fault -- as her love for him and desire for the comfort he offers takes over.

The man does nothing except tolerate the abuse at first, and then behaves soothingly as she breaks down. I think Marion Ravenwood did it to Indiana Jones in the original Raiders of the Lost Ark, and I've seen in it several other films as well, but I've never seen it in a video game.

It's kind of gimmicky, dramatically speaking -- you don't see it very often in real life. But the whole point of making computer simulations of human emotions in video games is to produce dramatic results in a medium that is, at the moment, pretty dramatically lifeless. I mention it because it nicely illustrates a mechanism that we don't often use.

Most of our emotional simulations use a simple sensation/calculation/behavior loop. Someone says or does something to a character; this influences his emotional state; he acts upon his feelings. His emotional state then reverts to a more neutral state over time (I was angry half an hour ago, but I've calmed down now), or changes again in response to another sensation.

If these systems are really simple they produce absurd results: a character is furious one moment and cheerful a second later, like a Warner Brothers cartoon character. This is the kind of thing you get with finite state machines.

This approach doesn't take into account the fact that behavior itself changes emotions. Behavior is not merely an output to be exhibited; it also affects how we feel. It feeds back into our emotional state. When the woman in the movie attacks her lover, the act of hitting someone she loves drains her anger away, and she begins to seek comfort because she has experienced such traumatic and violent feelings.

We all have behavioral techniques we use for self-comfort, some more acceptable than others. We punch a pillow or kick the dog. This doesn't qualify as behavior to satisfy a need, as in The Sims, because punching a pillow does not actually remove the source of the problem. All it does is relieve our feelings. (Mark Twain wrote, "When angry, count four. When very angry, swear.") But I think it's something we could build into games with little difficulty.

Depending on the character of the individual, behaviors can dissipate an emotion, or they can reinforce it. In the example I gave, the woman's anger dissipates because she is not by nature a violent person; in fact, the very fact of having acted violently distresses her.

On the other hand, in real domestic violence situations, the abuser often becomes even more angry as they harm the person they are abusing. They only settles down once the victim has stopped reacting at all. Their emotional machinery is severely twisted. This isn't a particularly happy subject for video games, but I think it's one that we could simulate if we had a dramatic need for it.

To make a character actually grow in a psychological sense (or, for that matter, spiral tragically into self-destruction) we have to create a meta-simulation -- a simulation that is capable of altering the basic emotional simulation that the game starts with. It could be something that interrupts the sensation/calculation/behavior loop and resets its variables. A key event or stimulus could convert a negative feedback loop into a positive one, or vice versa.

Drug abuse, for example, is a classic downward spiral. Suppose an addict character could encounter someone -- a charismatic teacher, perhaps -- who was able to supply the emotional comfort originally sought through drugs. The alternate source of comfort would disrupt the drug-seeking behavior, replacing it with a new dependence on the teacher... which could introduce its own problems into the story.

I'll admit right now that I don't know for sure how to do it. Until somebody funds me, I just write columns, not code. But I'm convinced it can be done well enough to make an entertaining and believable game.

I'm not proposing that we aim for total psychological realism -- after all, psychology is still in its infancy. Rather, I'm suggesting that we try to build a bit more richness into our simulations, in an effort to evoke more dramatically interesting behavior from our AI characters.

Computer characters at the moment are far too rational, and their behavior is pretty Vulcan: act upon stimulus to achieve goals. Real people aren't like that. They act against their own self-interest; they do irrational things; they do just plain stupid things. There's plenty of opportunity for experimentation.

Article Start Previous Page 3 of 3

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