One way a thought can come to mind involves orderly computation, and doing things in stages, and remembering rules, and applying rules. Then there is another way that thoughts come to mind. You see this lady, and she's angry, and you know that she's angry as quickly as you know that her hair is dark. There is no sharp line between intuition and perception. You perceive her as angry. Perception is predictive. You know what she's going to say, or at least you know something about what it's going to sound like, and so perception and intuition are very closely linked. In my mind, there never was a very clean separation between perception and intuition. Because of the social context we're in here, you can't ignore evolution in anything that you do or say. But for us, certainly for me, the main thing in the evolutionary story about intuition, is whether intuition grew out of perception, whether it grew out of the predictive aspects of perception.
If you want to understand intuition, it is very useful to understand perception, because so many of the rules that apply to perception apply as well to intuitive thinking. Intuitive thinking is quite different from perception. Intuitive thinking has language. Intuitive thinking has a lot of world knowledge organized in different ways than mere perception. But some very basic characteristics that we'll talk about of perception are extended almost directly into intuitive thinking.
What we understand today much better than what we did then is that there are, crudely speaking, two families of mental operations, and I'll call them “Type 1” and “Type 2” for the time being because this is the cleaner language. Then I'll adopt a language that is less clean, and much more useful.
Type 1 is automatic, effortless, often unconscious, and associatively coherent, and I'll talk about that. And Type 2 is controlled, effortful, usually conscious, tends to be logically coherent, rule-governed. Perception and intuition are Type 1— it's a rough and crude characterization. Practiced skill is Type 1, that's essential, the thing that we know how to do like driving, or speaking, or understanding language and so on, they're Type 1. That makes them automatic and largely effortless, and essentially impossible to control.
Type 2 is more controlled, slower, is more deliberate, and as Mike Gazzaniga was saying yesterday, Type 2 is who we think we are. I would say that, if one made a film on this, Type 2 would be a secondary character who thinks that he is the hero because that's who we think we are, but in fact, it's Type 1 that does most of the work, and it's most of the work that is completely hidden from us.
I wouldn't say it's generally accepted. Not everybody accepts it, but many people in cognitive and in social psychology accept that general classification of families of mental operations as quite basic and fundamental. In the last 15 years there has been huge progress in our understanding of what is going on, especially in our understanding of Type 1 thought processes. I'd like to start with this example, because it's nice.