There's a timely article on the subject in SitePoint,
http://www.sitepoint.com/captcha-inaccessible-to-everyone/

The article concludes:

> There is a fundamental disconnect in intent that means it is highly
> unlikely that a universally accessible CAPTCHA, or even a set of different
> CAPTCHAs will ever be devised.
>
> CAPTCHAs are, by definition, exclusive: they are are there to keep baddies
> out. Their way of testing “badness” does not allow for the legitimate use
> of machines. So they will tend to be inaccessible.
>
FWIW, the Code4Lib Journal had some reports of inaccessibility in the
captcha we were using (reCaptcha) and we eventually decided to jettison it.
It wasn't slowing down the spammers much anyway, as shown by our Akismet
stats.

Tom


On Mon, Feb 11, 2013 at 4:58 PM, Kyle Banerjee <[log in to unmask]>wrote:

> On Mon, Feb 11, 2013 at 1:02 PM, MJ Ray <[log in to unmask]> wrote:
>
> > It would also be very nice to replace the reCaptcha with something
> > that allowed people who can't pass audio-visual tests to take part!
> >
>
> I've always wondered what percentage of the population has trouble with
> reCaptcha challenges. I know I do.
>