systems of thinking - how to relearn According to Daniel Kahneman (Thinking, Fast and Slow), we have two types of thinking:

I. fast, instinctive and emotional
II. slower, more deliberative, and more logical


I found interesting Kahneman's remark that IQ score represents a person's System II ability (it does not measure System I nor the subject's ability to apply them appropriately).

I assume that it is possible to prioritize the System I early on in one's life because it is a fast way to the end.
(Example: In elementary/high school Maths, many tasks can be solved somewhat intuitively since they are simple reoccurring problems. And instead of real deep understanding of the rules, the problems can be solved by application of problem-solving patterns. This applies especially to situations when competition is promoted, thus speed is rewarded.)

Now, Is it possible (how?) to (re)train oneself to apply more of the System II?
2) Yes, I think so. If you think of your systems as a pattern recognizer, and continuously exposing it to more complex patterns and associated solutions, you can literally invoke your system 2 more easily, for example, in higher level math, you can prove properties and theorems in certain way that is efficient and effective, which depends on experiences to know what's the best method. Proving is certainly an act of system 2, it's complex and logical. Another example, meditation can be used to identify negative thoughts, once you recognize that you are being bothered by your own thoughts, you can immediately ignore them, this takes training of recognizing the pattern and let your system 2 focus your attention on other more important things than the negative thoughts brought up by your system 1. One more example is recognizing your own logical fallacies and cognitive biases. The key is to know the existence of the patterns, repeatedly recognize patterns, and correct/solve the patterns.