[gwern]

Actually, there was a weird recent re-analysis of Jaeggi 2011 using the Big Five psychology data they recorded for the subjects at the time, where the Conscientiousness (rough synonym for hardworking and self-disciplined) benefitted least in terms of far transfer/IQ while their scores improved the most: http://www.sciencedirect.com/science/article/pii/S0191886912...

[Sonthun]

Thanks for that article. In the abstract, they seem to state that they believe the conscientious didn't improve as much because they developed specific strategies for the particular game. So, they basically gamed the system instead of improving organically. It looks like you could vary the game rules and objectives to keep the conscientious from developing those strategies.