We may have different ideas about how much knowledge I'm trying to refer.

I'm not hoping that people come away from this article with a good understanding of how the primate brain calculates value and uses this data in decision-making. I'm merely hoping to explain that we do actually seem to be doing something like maximizing subjective expected utility - much to the surprise even of economists - and that neuroscientists know a great deal about how this works.

If you want the full story, you need to read a book. I've recommended several.