WebAIM - Web Accessibility In Mind

E-mail List Archives

Re: Alternatives for the CAPTCHA


From: Stephan Wehner
Date: Mar 23, 2009 11:40PM

On Mon, Mar 23, 2009 at 6:47 PM, Chris Hoffman < <EMAIL REMOVED> > wrote:
> Why not flip the problem on its head, and ask, "What are people really
> bad at that computers are good at?"
> Then provide a problem that a computer algorithm would get _right_,
> but that a human being would get _wrong_. Exploit the cognitive biases
> that we have but computers don't.
> Yet another approach would be to use natural language parsing
> problems, which are very difficult for computers. For example, ask
> "Which of the following is a valid English sentence: 'The dress Mom
> bought Dad's sister fits' or 'The dress Mom bought myself fits' ?"

The spammers would try three times instead of once, guess the valid
sentence, and get through every three times
on average: still far too often. This is the usual reason not to
implement such a system.


> --Chris