Cognitive models are the basic blocks of understanding we use the deal with the world around us. Don't worry, I'm about to explain just what that means. When we look at something or hear something we try to understand what it is by summing up it's parts. Using the smallest parts we already understand we match what we're looking at to the part we understand, do they overlap? If not we use other parts until we find one that does. If we don't have one then we think of a category of parts to put the new thing in and call that a part we understand.
Example: If we see a bicycle tire for the first time to try to understand what it is by matching it to things we already understand. If we know what a wheel is we'll call the bicycle tire a wheel. If we don't know that a tire is we might not be able to match it to anything and will therefore sum it up as well as we can: "a round metal and rubber thing".
When we have a lot of there parts we'll start to see that some things are made up from parts. For example a tree is made up from wood and leaves. And a car from metal, wheels and an engine. But to perceive these more complex things we can't keep using the parts that they are made up.
This would demand to much of our perception, our minds would be overheated immediately. Human beings can keep 7 +- 2 (ranging from 5 to 9 depending on a range of factors) things in our awareness at any one time. This means that it's possible to understand 7+-2 things at the same time. If you see a car and can only understand the parts, you'll freeze up due to overloading before you get past the car door.
Cognitive models are a way for human beings to abstract things, give them a name and remove the unnecessary information that isn't required to understand it. So I can add my wheel and engine and metal compartment parts together to form the model Car. I then place all the cars I see into that model and now I understand what cars are. At least until I see a completely different car.
Everything can be, and is, understood in this way. Try looking at something and looking at higher or lower layers of complexity.
Keyboard - buttons - plastic - rectangle shape.
Keyboard + computer part + writing interface + hand extension.
Pretty easy to understand huh? It gets a bit harder to think of things such as army maneuvers or Darwinian evolution as simple cognitive models but this is what makes humans work. Without cognitive models we would be very limited indeed. And we still are in some respects, to understand new things we compare them to already complex models. When they fully, or partly, overlap we categorize them together. But this means a lot of parts that don't belong get added to the model. This is called prejudice and is a huge problem for humans, no matter how open minded they are.
Next up, I'll explain how Raph Koster's theory of fun explains what fun is by using cognitive models.