IQ

Intelligence is the ability to make transformations in hypothetical dimensions

I did IQ research as a grad student, and it involved a lot of this stuff.
Did you know that most people ( 95% + ) with less than 90 IQ can't understand conditional hypotheticals?
For example:
- How would you have felt yesterday evening if you if hadn't eaten breakfast or lunch?
  - What do you mean? I did eat breakfast and lunch.
- Yes, but if you had not, how would you have felt?
  - Why are you saying that I didn't eat breakfast? I just told you that I did.
- Imagine that you hadn't eaten it, though. How would you have felt?
  - I don't understand the question.
It's really fascinating. We did research on convicts in San Quentin. They're absolute fucking retards, at least 50% illiterate.

Other interesting phenomenon around IQ involves recursion.
Example 1 :
- Write a story with two named characters , each of whom have at least one line of dialogue.
- Most literate people can manage this , especially once you give them an example.
Example 2 :
- Write a story with two named characters, each of whom have at least one line of dialogue.
- In this story, one of the characters must be describing a story with at least two named characters, each of whom have at least one line of dialogue.
If you have less than 90 IQ, this second exercise is basically completely impossible.
Add a third level ( 'frame' ) to the story, and even IQ 100's start to get mixed up with the names and who's talking.
Turns out Scheherazade was an IQ test!

Time is practically impossible to understand for sub 80's.
They exist only in the present, can barely reflect on the past and can't plan for the future at all.
Sub 90's struggle with anachronism too.
For example, I remember the 80-85's stumbling on logic problems that involved common sense anachronism stuff.
For instance:
- Why do you think that military strategists in WWII didn't use laptop computers to help develop their strategies?
  - I guess they didn't want to get hacked by Nazis?
Admittedly you could argue that this is a history knowledge question, not quite a logic sequencing question, but you get the idea.
Sequencing is super hard for them to track, but most 100+ have no problem with it, although I imagine that a movie like Memento strains them a little.

Recursion was definitely the killer, though.
Recursive thinking and recursive knowledge seems genuinely hard for people of even average intelligence ( although at San Quentin there weren't too many of those! )
It's the main reason why so many people with sub-90 IQ are sociopathic or psychopathic.
They don't have the mental computing power to model other people's thoughts and feelings.
I've seen it over and over with convicts.
Example :
- How do you think that man felt when you beat him?
  - Dunno.
- How do you think that boy's mother felt when she heard that her son was dead?
  - Dunno.
It comes across as psychopathic , but these people literally don't have the brainpower to build even a crude model of someone else's mind , let alone populate it with events that are in the past.