Interesting analysis but I think the last sentence sums up my sentiments: "Even if all the other issues could be dealt with and mindfulness meditation did improve arithmetic, what is it a valid proxy for?"
Improved arithmetic is a side effect. I doubt there is any way to meaningfully quantify the beneficial effects of mindfulness meditation. Any long-term practitioner would be able to tell you that.
Hmm. Tell Alan Wallace, the Shamatha Project, and the UC Davis Center for Mind and Brain! There's a lot of interesting variables and correlations to study in relation to meditation.
My Zen teacher talked about some Shamatha Project study that found sustained concentration meditation to decrease neuroticism and increase conscientiousness. Anecdotally, he confirmed that this is what he has seen as a meditation teacher.
I find it really weird to measure the efficacy of meditation by arithmetic puzzles, though. Is anyone claiming meditation makes you better at math? That doesn't seem like a big area of interest to me.
