Earlier quoted context omitted.
With DoubleRecall you don't prove that you are a human, but you prove that you've read the message so you get something in return = quality content.
Yes, I'm getting something in return, I get to take the desired action on the publisher's site. That's the case with any CAPTCHA. With the old CAPTCHA, I was at least helping convert printed books to digital formats. How is Double Recall different from Solve Media? It's obviously the same business model.
SolveMedia is a CAPTCHA system which verifies that you're a human, DoubleRecall is not a CAPTCHA system and it only verifies you read the advertisers message. It's much easier to decypher than CAPTCHA, so more straightforward.
We did more than 100 of design iterations on millions of people to come to the current simplistic design.