Your interactive post asks for money and has a disclaimer about "willing to give credit card number to an organization I trust". I think you might need a little more confidence here to ask for actual money, or perhaps a little more description on the other end.

"Buy this thing that might not work and I haven't described to you but could be amazing!" is a pretty big barrier to participation.

Avoided reading the rest of this post for the spoiler warning, started the interaction on the blog post, was bothered by the money question since how much I'd be willing to pay is directly related to how much money I have/make. (If I were willing to pay as much as $250, I'm doomed financially. If, on the other hand, this is how much we're willing to pay with a guaranteed conscientiousness increase, I'd expect to make back what I paid in the first month.)

V'ir gbyq zlfrys gung V fubhyq fgneg zrqvgngvat erthyneyl bu-fb-znal gvzrf va gur cnfg juvyr ohg sbe fbzr ernfba vg unq arire bppheerq gb zr gb orrzvaq vg. How comes?

B5 test taken -- 41th percentile. (You know you've been reading Less Wrong too long when on reading “cooperate” you think about the Prisoner's Dilemma.)

Given I have no problems enforcing daily habits on myself, most of your post is cruft for me. I'll reply to your boiled-down post:

I suspect meditation itself has a conscientiousness-increasing effect, mainly from making you allocate five minutes a day out of your time, but also because I think the relaxation might help in nonspecific ways.

I'm unclear on what you mean by "increasing conscientiousness." Are the non-specific ways necessarily non-specific? Can you cite any abstract benefits of daily meditation?

I suspect the "choose-your-own-adventure" precommitment and then following the directions also work to increase conscientiousness (while reading the article, at least). I am getting you to "buy in" (precommit) to doing what I tell you to do, and then following the steps is allowing you to experience the feeling of being conscientious in hopes that you can tap into that feeling later on.

"Suspect?" Is this a hypothesis? Is LessWrong the best place to gather subjects to conduct the experiment with?

As I see it, you post doesn't have the "mystique" surrounding it to derive the effect you're trying to achieve. Not not be harsh, but I expect this experiment to flop; there simply isn't enough intrigue here. This doesn't feel like it's ready to present to LessWrong—unless you have more to say about meditation.