How CAPTCHA discriminates against people who are blind

09 January 2019

On 31 January the cut off for opting out of My Health Record will close.

When the opt-out process opened in July 2018, Vision Australia identified quickly the process was inaccessible for people who are blind or have low vision, primarily the use of CAPTCHA. This meant the freedom to opt out was take away from the blindness and low vision community.

CAPTCHA refers to the “prove you’re not a robot” tests you are made to fill out before logging into many websites. They often involve deciphering text overlayed onto visually complex backgrounds, or identifying which images contain a car or storefront.

CAPTCHA is traditionally used to improve website security by making sure an online form has been completed by a real person.

For many people who are blind or have low vision, the usability of CAPTCHA is deteriorating especially for those users who rely on screen readers.

Because screen readers are machines too, they are unable to decipher text in an image, such as those used in CAPTCHAs. They need a text alternative (‘alt’ text), but to supply this for a CAPTCHA would be counterproductive to security.

People with low vision may also struggle because the text becomes blurry when magnified. Similarly, the distorted characters can be hard to decipher by people with some cognitive disorders, such as dyslexia.

Some CAPTCHA systems provide audio versions of the text; however, these cannot always be easily deciphered.

Vision Australia manager government relations Chris Edwards said through discussions with the Australian Digital Health Agency (DHA), Vision Australia was able to explain the importance of accessibility.

“It’s encouraging that after open conversations, DHA removed the need for CAPTCHA but we’d like to see this expanded to other government websites,” Chris said.

Given the accessibility issues with CAPTCHAs, New Zealand Government organisations are encouraged to avoid them and instead implement a number of alternative techniques to prevent or reduce access by bots.

“There are many different ways government, business and organisations can make their products and services, including their website, accessible to all and it starts with inclusive or universal design.

“Organisations need to consider accessibility at the development stage of a new website, not after it’s gone live. Retrofitting accessibility is infinitely harder than incorporating it during development.”

Vision Australia’s Digital Access team, recognised internationally as an industry leader in the provision of digital accessibility services, can help any organisation with their digital accessibility.

To find out if your digital presence is inclusive to all contact our Digital Access team on 1300 367 055 or