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Makes sense although I doubt having it so that only if you type a capcha you earn more and if you don't you earn less as being a fair and reasonable solution. It may have to be less biased.

Perhaps having the CAPCHA as a tool for SMT Distributors would be a good start.

Have sketched things in a bit further in a recent blog post. The link is included for your reading pleasure.

https://steemit.com/steem/@novacadian/a-decentralized-capcha-annonymous-proof-of-brain-verification