In his book “Thinking fast and slow” the Nobel prize winner Kahneman introduces
two fictitious characters “System 1” and “System2” to better explain how our brain works. These two characters can also better explain how our memory works.
System 2 is our slow, deliberate, analytical and consciously effortful mode of reasoning about the world that we apply when we try to compute for example
12×37 . It uses memory like a computer .
System 1, by contrast, is our fast, automatic, intuitive and unconscious mode of thinking. This is the reasoning that will make you jump
on the side walk when you hear a klaxon of an approaching car. And you discover
that this jump has saved your life. Its main purpose is to scan continuously the
environment in search of signs of danger. And when it finds something strange to produce an immediate reaction that saves us. For this reason I call System 1 the “guardian angel in our brain”.
System 1 uses memory in a peculiar way. It has two main problems to do its work:
- The analysis must be fast, so it activates continuously all neuronal pathways connected with what our senses are detecting. This activation (associative memory) brings as much as possible to memory to help to check
that everything is ok. One of the results of this brain activity is the phenomenon of priming. The study of priming has shown that this activation is
done in parallel on all words, objects and actions connected with what we are
sensing (Strange odour in kitchen, gas, open the window, close the oven ….)
- System 1 has also the need to delete quickly some of the activated ideas
that we don’t need any more in order not to overcharge our brain with unwanted stuff. This is done in an elegant and efficient way. This can be seen following
System 1 as we walk in our house. In order to check that there is nothing strange it must load a map of the whole house in our memory to compare what we
see with what we remember. This can be a lot of information but it seems that
it is loaded in parts room by room. When we pass a door the information about the room behind us is replaced with the information about the new room.
This works so well that sometimes when we arrive at the refrigerator we have
completely forgotten what we wanted.