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Captcha and inaccessiblity

From: Tom Croucher <tcroucher@netalleynetworks.com>
Date: Sat, 18 Oct 2003 15:18:23 +0100
To: w3c-wai-gl@w3.org
Message-ID: <oprw8soxm9u930jj@mail.icet.co.uk>

Captcha stands for "Telling Computers and Humans Apart (Automatically)". It 
most commonly involves using an image with warped text in it to 'verify' 
that it is a human and not a robot submitting a form on the internet. 
However the problem is that currently all the systems rely on putting a 
piece of information in form which computers cannot interprete and asking a 
human to repeat it back. This is becoming more widely used, yahoo uses it 
to verify mail being sent, network solutions use it to stop third parties 
piggybacking on their whois lookup system. With spammers and other service 
abusers so prevelent the big service providers are keen to protect 
themselves but obviously this has impacts on accessibility.

I spoke to the guys at CMU about some stuff I was interested in with text 
based captchas a while back (6mo maybe) and they said they were working on 
a text version. This would probably take the form of a question which is 
common knowledge or analogic. ie, "If I have five apples and I eat three. I 
give one to Bob but Susan gives me two apples, how many apples do I have?". 
To which the acceptable answers would be "3", "three", "3 apples", "three 
apples". Another example might be like those IQ tests "A dingy is to ship 
as a go-cart is to a?". The acceptable answers being "Car", "Bus", "Lorry" 
etc.

The other obvious way to go would be audio, so generate a word in an audio 
format or some other sound. So, "What animal makes this sound?" stuff like 
that. Which is almost inevitabley easier than finding a way to generate 
textual questions which are understandable enough to humans, but obscure 
enough to Natural Language Processors and Cognitive engines, without being 
so long and convulted they are obnoxious to use.

Some vague thoughts and possible solutions. I would love to hear ideas 
people have on ways we could make this work without the currently 
inaccessible images. I think we should insist that if people must use image 
Captcha they either also provide audio ones or a phone number that people 
can use to a bypass code.


Tom
Received on Saturday, 18 October 2003 10:18:30 GMT

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