So let us take a look at what is a cognitive system.
Notice that I'm using the term cognitive system and
not the term knowledge-based AI agent. I could have used that term also.
When we talk about knowledge-based AI agent, then we could take two views.
One view is that we are going to build a knowledge-based AI system, which need
not be human like. Another view is that the knowledge based AI agent that
we will build will be human-like. The cognitive system is situated in the world.
Here by the world I mean the physical world. For example, the world that I
am interacting with right now, with this screen in front of me and
this microphone. This world is perceptionate. There's an example, the percept
something being a straight line or a color of some object. Or the smoothness of
some of the texture of some object. This perceptionate around the world and
cognitive system is using sensors to perceive this percept. That's the input of
the cognitive system. The cognitive system also has some actuators. So, for
example, I have fingers that I'm using right now to point to things. And
a cognitive system uses actuators to carry out actions on the world.
Cognitive system then is taking perceptor's input and giving actions as output.
So far, we've talked about a single cognitive system. But of course one can have
multiple cognitive systems. These multiple cognitive systems can interact with
each other. Just like a cognitive system situated in a physical world,
it is also situated in a social world. Let us now zoom into the inside
of a cognitive system. What is the architecture of a cognitive system?
So the cognitive system takes as input certain percepts about the world. It has
a task of giving as output actions of the world. The question then becomes, how
can these percepts be mapped into actions? One way of mapping them is that we
will do a direct mapping. These percepts will be directly mapped into actions.
Let's take an example. Imagine that you're driving a car, and the brake lights
of the car in front of you, become bright red. Should that happen, you will then
press on the brakes of your car. Well, that is an example of a reactive system.
The percepts were that the break lights on the car in front of you became bright
red and the action was that you pressed on your own brakes. In doing so,
you may not have planned. This is now a direct mapping of percept into actions.
Alternatively, consider a slightly different problem.
Again you're driving you're car on the highway, but
as you're trying to drive on the highway your task this time is to change lanes.
Now, in order to change lanes, again you may look around and
look at the percept of the road. There are other cars on the road, for
example, and you need to take some action that will help you change lanes.
This time you may actually deliberate, you may actually look at
the goal that you have as well as the percepts of the environment and
come up with a plan that will tell you what action to take. As we discussed in
the last lesson, the deliberation itself has a number of components in it.
Three of the major components that we'll studying in this class are learning,
reasoning, and memory. These three components interact with each other in
many interesting ways that we will decipher as we go along.
Now, deliberation was reasoning about the world around us. So
if I take that example again of changing lanes, as I'm driving on the highway,
then I'm reasoning about the world around me. Where are the other cars? Should I
change lanes to the left or to the right. Metacognition on the other hand,
the third layer here, has to do with reasoning about the internal mental world.
So metacognition reasons about the deliberation. Or metacognition can
also reason about reaction. Let us take an example of the metacognition also.
Image again that I had to change lanes. And I did,
as I changed lanes to the left, the cars behind me honk because I
did not leave enough space for the car that was already moving on the left lane.
In that case I know that the lane changing did not go very smoothly.
I may now think about my own actions in the world, about the deliberation that
led to those actions, and I may then decide to change or reconfigure, or
repair the deliberation that led to that sub-optimal plan for
changing the lanes. That is an example of metacognition. So now I
have this three layered architecture, reaction, deliberation, metacognition.
Note that we have defined intelligence in a way, intelligence here is
about mapping percepts in the world, interactions in the world. Intelligence is
about selecting the right kind of action given a particular state of the world.
But there are many different ways in which we can map the percepts into actions.
Purely reactive, deliberative, or
also entailing metacognition on the deliberation and the reaction. This then is
the overall architecture of the cognitive system. This is called a three layered
architecture. We'll be returning to this architecture many times in this course.