This sounds like a bunch of pseudoscience? I've taken a bunch of courses on neurosciences etc, and there's certainly some left/right splits but nothing as severe as that…
Probably more like outdated conjecture than pseudoscience (Sagan’s book, “Dragons of Eden”, was written in the 1970s), but point taken — contemporary neuroscience talks more about a modular theory of the mind than a strict Right / Left split.
The wiki article is actually pretty accurate: https://en.m.wikipedia.org/wiki/Lateralization_of_brain_func...