Captcha and accessibility

I’ve written before about the problems with anti-spam devices, but today I read some wonderful blog posts on this, and since I’m neither a user with a dsiability that prevents me from using CAPTCHA, nor an expert on accessibility for users with visual impairments, I will let the posts speak for themselves:

  • One user’s experience trying to sign up for a Gmail account, which failed because CAPTCHA has accessibility problems.
  • A study, showing that this is the majority experience of CAPTCHA (73% of users were unsuccessful using the ‘accessible’ version of CAPTCHA)
  • A discussion of the issue at Feminists With Disabilities, noting that to provide Google with feedback, you have to get through Captcha first, and how this further disavantages an already disadvantaged user population.
  • A link to the Google accessibility reporting function–please use this liberally if you notice any other problems with Google’s interfaces (and you have been able to sign up for an account).

As this article on anti-spam devices points out, it’s not just users with visual impairments that suffer when presented with CAPTCHA, it’s also users with reading difficulties, and even users without disabilities suffer some inconvenience.

It is telling that  one of the best cited posts on Captcha effectiveness (which finds CAPTCHA to be very effective) refers only to the ability of CAPTCHA to prevent spam. The “false positives”, where CAPTCHA fails to allow a human being to access a website, are dismissed with a single line “these are eminently human-solvable, in my opinion”, while pointing out that CAPTCHA is used on most interactive internet sites.

Spam is a usability and accessibility problem, but the way to solve it should not prevent users with disabilities accessing internet content. Not only is CAPTCHA as an approach inaccessible and unusable, but it’s widepsread implementation could end up costing sites which use it a lot of money.

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1 Response to “Captcha and accessibility”


  1. 1 John Mc Thursday, September 8, 2011 at 8:39 pm

    I completely agree. Actually, I can’t believe we’re still even using CAPTCHA in this day and age – surely there must be a better way to prevent spam.

    I’ve written about some interesting ideas people have had to replace CAPTCHA (http://www.itdonut.co.uk/blog/2010/08/garbled-text-and-kittens-how-prove-youre-human), but I’m not sure if any of these really address the inherent accessibility problems.

    Maybe we need to do away with them altogether, and find a more intelligent way to separate genuine feedback / comments etc from everything else.


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