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Earlier quoted context omitted.
There's a recycle button that will generate a new one.
I guess the issue is, does Google know when someone recycles a captcha, and if they do, are they doing anything about it? It's useless if the captcha isn't flagged and is just given to another use.
One nice thing about recaptcha is that you know those cut off words don't matter (badly OCR'd) and can just enter gibberish for them. But it has gotten to the point that about half of the control words are unintelligible by a human.
You are presented with two strings - a potential word scanned from a book and a random mash of letters. You only need to enter the random letters correctly, you can write whatever you want for the word from the book. Meaning, if one of the two is obviously a bug in OCR software (or is non-latin characters you can't type), just write your favourite curse word -- I go with captcha -- and it will work.
As for the "unreadable mash of letters" problem, I could read them in all his examples. Though I have seen some cases when they are really unintelligible.
If you must use reCaptcha on your website, do it like 4chan -- when you mess up the captcha, you are automatically given a new image to try, without being sent away or having to enter what you just typed again.
Which just means you'll only limit the rate at which bots register -- the article mentions something like 10% success rate of current-generation bots guessing reCaptcha.
Instead of displaying a static captcha, display a dynamic one, with letters going through elastic transformations. Humans are pretty good with video sequences. Computers are not.
As a side effect this may help pushing computer vision algorithms to working with videos, rather than static images :)
It's easy to criticize captchas. That's why there are so many articles like this, which we all knowingly nod along to as we read. It's much harder to provide productive criticism that leads to an actual improvement over the status quo. (Although it is easy to suggest bad alternatives to captchas, which is why they appear in every comment thread about captchas on Hacker News, including this one.)
Why not pose questions with answers that are obvious to humans but difficult for ai. Eg. 'What's 4 times four?' or 'How many times does the word four appear within this sentence?'
> http://www.wolframalpha.com/input/?i=what%27s+4+times+four
For an interesting alternative to traditional captcha check out Solve Media - they monetize your captcha for you by making you input brand messages (that are retained better than just seeing a banner ad). I thought it was an interesting idea when I met the founder Max & team (although I was just slightly skeptical of the level of security provided). They seem great though, so it's worth checking out.
Problems with Solve's captchas:
* Requires Flash plugin
* Contains sound (not critical to solving a captcha but not great when your laptop suddenly plays ad audio in a library)
* Payout rates are horrible. You earn a few cents for every couple thousand video captchas solved. Successful solved percentage rates are also poor
I see a possible solution that may work in a short term: Instead of displaying a static captcha, display a dynamic one, with letters going through elastic transformations. Humans are pretty good with video sequences. Computers are not. As a side effect this may help pushing computer vision algorithms to working with videos, rather than static images :)
CAPTCHA seems relatively pointless at stopping spammers since there are dozens of online services that use human labour to solve them for a dollar per thousand. In tests on my own sites I've found that introducing reCAPTCHA during the registration process leads to a significant increase in people abandoning their registration when they fail at recognising the text the first time, without putting a significant dent in…
Randomizing the field names is a great idea but as you said they would just need to scrape the HTML each time they wanted to register. Have you considered sprinkling in random bits of markup to throw off the people using regex and other lazy parsing methods? That might make it a real pain to scrape your forms depending on how the spammer parses your page.
I'm catching about 100 spam accounts a day with this technique[1] and the ones that I miss are fairly easy to detect through analysis once they start using their account.
He seems a bit ignorant on how reCaptcha works nowadays. You are presented with two strings - a potential word scanned from a book and a random mash of letters. You only need to enter the random letters correctly, you can write whatever you want for the word from the book. Meaning, if one of the two is obviously a bug in OCR software (or is non-latin characters you can't type), just write your favourite curse word --…
