I've played poker for play money. There's not as much pain when losing so there is correspondingly less motivation to exercise discipline, come to correct beliefs, or deal seriously with the difficult psychological situations. Learning to take those things seriously and perform under "survival instinct"-level pressure is the point of this training. You want the actions you take to imprint your habits and reshape them to be more rational over time and play money can't do that. See the post I linked to above for a longer explanation.
The football study you link to shows me that in cases where there's already a rich information market, real and pretend markets both mirror it well. That doesn't indicate to me that people wagering in the play money markets had a similar visceral experience or would learn the same lessons from failure or success. I strongly suspect they didn't -- and would bet money on it if I could figure out how.
Playing poker for play chips online quickly teaches that there's a huge difference between $0.01 and $0.00 when it comes to quality of play. Games that don't require something be risked end up being jokes.
Related to: Problem of verifying rationality
We're excited to announce the (soft) launch of RationalPoker.com! It's a new guide developed by me, Zvi, Kevin, and patrissimo detailing how to use online poker as rationality training to conquer your cognitive biases. We want our community to go from knowing a lot about cognitive biases to actually having a training method that allows us to integrate that knowledge into our habits -- truly reducing biases instead of just leaving us perpetually lamenting our flawed brain-ware. In the coming weeks, we'll be making the case that online poker is a useful rationalist pursuit along with developing introductory "How To" material that allows those who join us to play profitably.
We want to make sure we aren’t wasting our time practicing an ungrounded art with methods that don’t work. Poker gives us an objective way to test x-rationality. The difference between winning and losing in poker once you know a small amount of domain-specific knowledge is due to differing levels of rationality. Our site will be presenting the case that a strong rationalist who can act on their knowledge of cognitive biases (a defining feature of x-rationality but not traditional rationality) should have a distinct advantage. We'll be offering the connecting material between the sequences and online poker to teach you how to apply knowledge of cognitive biases to poker in a way that verifies your current level of rationality and naturally teaches you to improve your rationality over time.
Incidentally, this also presents a solution for those of us looking to earn money from anywhere with a flexible schedule that leaves time for outside interests.
We’re just getting started so please be kind! Our site is definitely not a final product yet. If you're curious about where we're going with this though, add us to your RSS feeds or check the site every few days. We hope some of you who aren't convinced yet consider playing once you feel like we’ve finally given you enough information to understand why poker is a profitable rationalist pursuit.
Also, if you sign up for one of the online poker rooms like Full Tilt using our affiliate links, the residuals get donated to Less Wrong/Singularity Institute. That way, the more poker you play after you sign up, the more money you direct towards raising the sanity waterline and creating provably friendly artificial intelligence.
We’re not counting on it, but even a very small group of us could theoretically fund SIAI in a very real and meaningful way just as a side-effect of playing a lot of online poker. I know I'm partisan, but this seems like an unreasonably exciting opportunity! So if you support SIAI and you (or your friends) want to sign up to play online poker anyway, please sign-up using our links.
Anyway, we hope some of you want to get stronger by joining us in the Rationality Dojo of online poker. You can be part of our crew of aspiring rationalists who want to increase our rationality, earn money, and help save the world -- all by playing a fun computer game with no boss, no schedule, and the potential for lots of self-development and personal growth.
So check out our site and let us know if you're interested in joining.