CAPTCHAs shown to yet again impede accessibility

Monday, 6 June 2011 16:30pm

The question of accessible CAPTCHAs has been raised once again as they are shown to impede ticket purchase on the 2012 London Olympic website.

AbilityNet, a charity helping adults and children with disabilities use computers and the Internet, has found that the audio alternative to a CAPTCHA on the 2012 London Olympic website could stop people who are blind or vision impaired purchasing tickets.

A CAPTCHA is a challenge-response test that was originally created to ensure that the response given was from a human rather than from a computer. A common type of CAPTCHA requires that the user type letters or digits from a distorted image that appears on the screen. People who are blind and vision impaired can listen to an audio alternative, provided that option is available.

According to Robin Christopherson, AbilityNet Head of Digital Inclusion, the audio alternative was distorted to a point where he couldn’t work out the words that were being spoken that would enable him to pass the ‘CAPTCHA test’.

Others have been commenting on the inaccessibility of CAPTCHAs. Paul Boag, owner of Headscape, created a short video about Google’s CAPTCHA system. Boag’s key points are:

  • When you click on the audio version of the CAPTCHA, there is no explanatory text
  • Like on the 2012 London Olympic website, it is hard to understand an audio CAPTCHA due to distortion
  • Users cannot refresh the CAPTCHA to generate a new test
  • The icon to access the audio version of the CAPTCHA is a wheelchair icon, an image that has no relationship to the auditory CAPTCHA needed by people who are blind or vision impaired

There are more accessible CAPTCHA systems available that make it easier for all users, such as the Textcaptcha (based on logic questions) and DISTCHA which asks you to slide an icon across the screen with either mouse or keyboard. Neither Google nor the Olympic committee are using these alternatives.


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