CAPTCHA

Summary

If you have ever registered for an account or paid online, you may have seen some of these CAPTCHA tests:

• a checkbox for “I’m not a robot,”
• an image of wavy text,
• an interactive puzzle where you must click all pictures with cars.

These tests help filter out spam or bots. But at the same time, they become an unsolvable obstacle for people with certain disabilities. Because CAPTCHAs are designed to be unreadable by machines, screen readers can not read those wavy lines of text; people with cognitive impairments cannot always answer puzzle questions, etc. That’s why you must use at least two forms of CAPTCHA involving different senses of perception. For example:

• provide an audio CAPTCHA for those who can’t see;
• provide a visual CAPTCHA for those who can’t hear.