I know I’ve been batting around a lot of the accessability issues with CAPTCHAs and turing tests in general when used to discriminate against robotic activity and how that relates to the blind. Sometimes what I talk about is theoretical and sometimes it’s not. Here’s a case in point. Target had a class action suit filed against it by the National Federation of the Blind (NFB).
My general feeling on this matter is it is always better to allow alternate applications to visual CAPTCHAs. Audio versions are one example. Email is another example. Out of bound methodologies can provide reliable alternatives to visual CAPTCHAs and can still allow users to proceed through the flows in question.