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Re: Alternative CAPTCHA


From: Simius Puer
Date: Aug 26, 2009 4:10AM

> >Hmm, an interesting CAPTCHA-substitute here. It has a text question,
> >with ALT-ed images as answers. The ALT isn't a direct answer but
> >gives an easy clue. Works well for screen-reader.
> >Would any groups be disadvantaged by this?

CAPTCHAs have long standing accessibility and usability issues and this is
yet another great example of an attempted work-around with its own issues.

"Would any groups be disadvantaged by this?" the answer is yes. In terms of
*accessibility *this could hamper users with cognitive disabilities. I've
not tested the page using any assistive technology but it appears to tab
right over images making me wonder if there are any issues for non-sighted
and/or non-mouse users. Accessibility aside there is a much wider *usability
*impact in using CAPTCHAs.

Consider older generations or people who don't use the Web very
often...these people are often unfamiliar with CAPTCHAs (often one of the
primary arguments for using them) and it can create alienation that leads
them to abandon the submission. There are also people who use the Web on a
regular basis, that suffer from no disability at all, and yet still struggle
with CAPTCHAs.

Causing confusion or creating any workload (i.e. solving a CAPTCHA) for the
user does one thing - it reduces the amount of genuine submissions. Not
something any organisation, profit making or otherwise, would aim for.

The thing is that there *are* alternatives to CAPTCHAs , ones that are both
usable accessible (if implemented correctly of course) and more importantly
- do *not* put any additional workload on the user.

*"Spam-free accessible forms"* - WebAIMs own Jared Smith
Looks at alternatives and provides real-world examples of code - essential
reading (over 2 years old and still utterly relevant)!

*"CAPTCHAs' Effect on Conversion Rates" *- Article by Chenry on SEOMoz
Need to convince the boss not to simply take the "easy" route to spam
prevention? This is an excellent basis for a business case backed up by
results from a study.
*I also have a small article "Preventing spam in Web forms without CAPTCHAs"
on my own site. It's a very high level (non-technical) introduction to the
issue and the business considerations surrounding the choice of solution.