I studied CS and it seems to me that it did not taught critical thinking all that much. It taught logical thinking. We have tendency to create simplified model of the world, make logical inferences on it and then ignore actual messy real world evidence when it contradicts our theories.

So, the caricature of a STEM student will make theory in his mind and then ignored pretty much all nuance in the article the theory is based on.

Another example would be bias. The history students are specifically trained to deal with bias in source material and accept that every single historical source is biased by own point of view. The amount of STEM graduates who split world into two neat categories "biased" and "non-biased" is staggering.

All of these are elements of critical thinking.