The Emotion Machine

formulate high-level descriptions like “a palm-shaped object with fingers attached.”

Certainly, many things that we do are based on reacting to external events by using simple If–>Do rules. However, along with those low-level reactions, we are also always making new plans and thinking about what we’ve done in the past—and those internal mental activities are what give us our unique abilities.

For example, when Joan reacted to that moving car, her reaction was partly instinctive and partly learned. However, she could not have ‘learned from experience’ that cars are especially dangerous—because if she had learned this by trial and error, she probably would not be alive; learning by ‘reinforcing’ success is a really bad way to learn to survive. Instead, she either ‘figured this out’ for herself or was told about it by someone else, and both of these must have involved higher levels of mental activities. So now let’s turn to what we call ‘thinking’—that is, the techniques that we use when we react, not just to events in the outer world, but also to other events in our brains.

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§5-3. Deliberation

When Joan chose “whether to cross or retreat”, she had to choose one of these rules to use:

If in street, Do retreat.

If in street, Do cross the street.

However, for Joan to make decisions like this, she needs some way to predict and compare the possible futures those actions might bring. What could help Joan to make such predictions? The simplest way would be for her to possess a collection of three-part If–>Do– >Then rules, where each If describes a situation, each Do describes a possible action, and each Then depicts what might be a likely result of it.

If in street and Do retreat, Then arrive a bit later.

If in street and Do cross, Then be slightly earlier

If in street and Do cross, Then may be injured.

But what if more than one such rule applies to the present situation. Then one could choose which rule to use by comparing the different results they predict:

Thus, these three-part rules would allow us to do experiments in our heads before we risk making mistakes in the physical world; we can mentally “look before we leap” and choose the more attractive alternatives. For example, suppose that Carol is playing with building blocks, and thinking of building a three-block arch:

Right now, she has three blocks arranged like this:

So, she imagines a plan for building that arch: first she’ll need room for her arch’s foundation—which she could achieve by using this rule: If a block is lying down, and you Stand it up, Then it will use up less space on the ground.

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Then she’ll stand the two short blocks on their ends, making sure that they are the right distance apart— and then finally place the long block on top of them. We can imagine this sequence of rules as describing the changes in scenes between successive frames of a movie clip.

To envision that four-step sequence of actions, Carol will need a good many skills. To begin with, her visual systems will need to describe the shapes and locations of those blocks, some parts of which may be out of sight —and she’ll need ways to plan which blocks to move and where she ought to move them to. Then, whenever she moves a block, she must program her fingers for grasping it, and then move it to the intended place, and finally to release it there —while taking care that her arm and hand won’t collide with her body or face, or disturb the blocks already in place. And she’ll have to control the velocity, to deposit the block on the top of the arch without tumbling down its supporting blocks.

Carol: None of those seemed like problems to me. I simply imagined an arch in my mind—and saw where each of the blocks should go. Then I only had to stand two of them up (making sure that they were the right distance apart) and then place the long one across their tops. After all, I’ve done such things before. Perhaps I remembered those other events, and simply did the same things again.

But how could Carol ‘imagine’ how the scene would look after moving a block, before she even touches it?

Programmer: We know ways to make computers do that; we call it ‘physical simulation’. For example, in each step of a new aircraft’s design, our programs can precisely predict the force on each of its surfaces, when the plane is propelled through the air. In fact, we can do this so well today that we can be virtually certain that the very first one we build will fly.

No human brain can do such huge calculations, but we still can make useful predictions by using our commonsense If–>Do–>Then rules. For example, when Carol was planning to build that arch, she might have imagined a step in which she places the long block on just one of the short ones: