I wonder if there is not some type of cultural effect here, though. Certainly, if two guys went out hunting, and one came back with three squirrels(or whatever), and the other came back with, say, seven, wouldn't they innately realize how one did much better than the other?
Interesting study, no matter what the outcome.
And as an interesting aside, years ago I read a book by a fellow who had gone down and spent a few years with the Yanamamo tribe. He became very accepted by them, learned the language, and eventually married a native Yanamamo woman.
IIRC, he brought her back to the US, and she was totally disfunctional. Couldn't understand even simple concepts like WALK/DON'T WALK at street corners. So impaired, that she eventually had to return to the Amazon jungle.