CAPTCHA and Accessibility - Is This the Best We Can Do?

Web access is affected by a great amount of accessibility issues that do not allow some users to access all information presented. Therefore, Web accessibility is an important issue because everybody should access Web content independently of their access features. Among these accessibility issues, a Web content element that interferes with Web accessibility is a CAPTCHA. A CAPTCHA is a challenge-response test used to determine whether or not the user is a human instead of a computer or a robot. This type of element causes accessibility barriers especially to users with disabilities. This paper presents an overview about Web accessibility and CAPTCHA. Besides, an analysis of the accessibility barriers and a solution proposal depending on the type of disability is provided. Moreover, a survey of CAPTCHA approaches is introduced and its results are shown. With the knowledge gathered, a data discussion is provided. The lesson learned is that the CAPTCHA objective must be that security checks should be responsibility of websites or servers, that is, they cannot be delegated to the user.