Verification CAPCHAS: Are they accessible?

Want to post an ad on Craigslist? Want to make a comment on a blog post or article? Want to subscribe to an email list? Wherever you go on the Internet, you will surely encounter CAPTCHAS. You know those twisted words that block or enable entries on websites?

CAPTCHA is an acronym that stands for Completely Automated Public Turing test to tell Computers and Humans Apart. CAPTCHAS were established to block spamming machines from posting wherever they wanted. In order to keep out spammers, a CAPTCHA has to effectively test if one is a human or machine. So, computer scientists determined that one of the simplest ways to accomplish this is to use images of language. This is because characters , unlike images, are able to be deciphered by the human eye and programmed precisely by whoever creates the CAPTCHAS. In order to deceive potential spammers, the images of language take random generated text and manipulate the image, so that a human can read it, but a computer trying to take a picture of it cannot.

ReCAPTCHAS

reCAPTCHA displays a series of characters within an image in order to prevent dictionary attacks, which the user is asked to enter. This letter code is visually distorted to deter OCR bots or machines. Often times, people living with no disabilities, have difficulty in identifying the correct characters when first attempting to decipher them. ReCAPTCHAS comes with two options for accessibility:

• The option to request a new set of characters, if the present set is illegible.
• The option to play audio where the characters are spelled out verbally.

The reCAPTCHA option has various accessibility issues despite having the option to obtain a new ReCAPTCHA or choosing to hear the audio version.

• People with low vision dependent on using screen magnification software to enlarge text to have the ability to read it will encounter issues. This is because they will need to enlarge the ReCAPTCHA to be able to read the characters. This in turn, will distort the ReCAPTCHA characters even more than they are already.
• Users who elect to hear an audio version of the ReCAPTCHA may not be able to understand the names of the characters due to poor sound quality.
• Audio versions of a ReCAPTCHA also pose challenges for screen reader users. They have difficulty hearing the letters being verbalized while simultaneously searching for the text box to enter the letters as every keyboard keystroke performed, screen readers verbalizes it.

Alternative CAPTCHAS

A question-based option is an alternative user verification option. A question-based verification consists of answering a simple math problem or a question, like “2+2=?” Since math is universal, there is no language barrier to international users but this may not be so with the question CAPTCHA. As a result, it would be best to use a simple math question as this will be accessible and user friendly to all.

Another type of user verification is via email. This is where a user confirms via email that they are not a machine when clicking on the link provided to them in the confirmation email sent to them.

While the reCAPTCHA is the most widely used human verification option today, there are alternative accessible options to confirm that a human is a person and not a machine.