I'd wondered if the "CAPTCHAs digitize books!" story wasn't an urban legend for a while, though the font certainly looks like it came from something being digitized.  But then I saw, "Stop spam.  Read books" next to a CAPTCHA, and figured it was finally worth googling.

Turns out they're really just captcha-ing one word. Then the second is all labor donation.

What is reCAPTCHA?:
But if a computer can't read such a CAPTCHA, how does the system know the correct answer to the puzzle? Here's how: Each new word that cannot be read correctly by OCR is given to a user in conjunction with another word for which the answer is already known. The user is then asked to read both words. If they solve the one for which the answer is known, the system assumes their answer is correct for the new one. The system then gives the new image to a number of other people to determine, with higher confidence, whether the original answer was correct.

So if you've figured out which is more likely to be the known word, you could type "watermelon" for the second and protest, I guess.  Still, I'm not sure how I feel about CAPTCHAs required for logging in to a system/creating an account also requiring that you donate your time to Google.  I understand how it benefits the web site admin that installed the CAPTCHA, but there's an implicit ethics embedded into the free labor requirement.

Labels: , ,