[bgurupra]

actually I can see how this will get down voted - but if a person has a smart phone what are the chances he can't really pay for this coffee? (not a rhetorical question but a purely probabilistic one) - so maybe this experiment may not test the true altruistic nature of people but more the curiosity of participating in an experiment like this?

[Shenglong]

I think it's more - sometimes you want to, sometimes you don't want to pay for a cup of coffee. Though, I don't think the experiment is to see if people are willing to give coffee to those who can't pay for it.

It's an experiment on social contribution, if I'm correct. Even though you can leech (and some will), a good amount of people might ultimately add more money than they spend from it. But why? Everyone is anonymous (kind of), and it's not like you have external pressure to be good.

If the amount on the card stays positive, you may have renewed my faith in at least a portion of mankind, Jonathan Stark.

[startupfounder]

Maybe it is a thought experiment, but what we see from Brian's story is that this thought process can be taken outside of the tech/HN/twitter bubble we all live in. It might kind of be enlightening to try this out in the real world (buy a coffee with cash for a stranger) then come back and share your experience.