> when they tested good chess players on random board positions they were just as good as people that did not play chess.

Doesn't that prove the opposite as the statement in the first paragraph if they were only as good as non-players? I assume there's a typo in there somewhere because I would expect the original thesis to be true. My gf would squarely beat me at chess960 just because she sees the relations between the pieces a million times faster. She can walk into a room and look at the board I've been 'rearranging' (playing on) for 45 minutes and still know what I should do faster than me

It sounds like they're recalling a study where they looked at brain activation and accuracy when trying to memorize random positions vs “real” positions, which is a very different thing.