The autistic brain
There are essential differences between the neurotypical and autistic brain in the perception of the external world and the process of producing thoughts and ideas. The former uses an abstract concept as a base to conjure specific examples, imagery, thoughts, etc. The latter functions in reverse. The autistic brain needs multiple specific examples in order to be able to create an abstract concept that it's then able to use in a similar manner. Abstract concepts are basically categories in which objects, animals, people, environments, etc. are sorted.
The neutotypical brain is very good in the instinctual use of abstract concepts. For example, a square with a triangle on top is a universal representation of a house. This icon, though, is really a very simplistic generalization and differs immensely from the actual, realistic nature of a house. In spite of that, the icon is an extremely useful way of filing all objects with similar qualities that fall into that category. When you are asked to imagine a house, you create a picture in your mind, or a richer sensory thought, that covers the most basic characteristics that you have associated with the concept of a house. The house you imagine doesn't have to literally exist. You are capable of internally creating your own faithful version.
The autistic brain, in most cases, does not function in this way. The extraction of a symbolic representation of an object, environment or person, that will have a lower, simpler resolution for higher usability, is very difficult for an autistic person. For example, if asked to imagine a church, they can only summon images of specific churches they have already seen. They are hard-pressed to create an original icon based on the general features of a church. This happens because the autistic brain tends to obsessively focus on each and every detail. Initially, for an autistic person, two different churches don't constitute two samples of a more generalised, abstract category of “churches”. Instead, they comprise two totally distinct and unique categories. Nevertheless, with more and more examples of churches embedded in memory, the classification of all of them in a single category, becomes all the more easier.
The parent of an autistic child uses the same route every day to reach the school. However, one day it's necessary to make a small detour, maybe for a quick purchase. It could be that the new route is almost entirely unchanged, except for one block where an extra turn to a sidestreet is taken before they return to the previous street. The neurotypical person easily realizes that the detour doesn't invalidate the understanding of the rest of the walk, since most of it is still known. Yet, the autistic child immediately sees a wholly different route, because that small deviation transforms the journey into a completely new and different experience. This means that it's impossible to make short-term predictions, since they have never been in that position before, and, understandably, panic kicks in. Likewise, an autistic child can have a fit if a vase or a chair at the living room has changed positions, because in an instant they are in a very unfamiliar place. Imagine being accustomed to the maze that is your home, and from one moment to the next, you find yourself in a different and unrecognizable labyrinth. The familiarity and safety that your personal surroundings so importantly provide, have vanished.
