CAPTCHA systems for disabled people

Nowadays the Internet users are from different ages and groups. The disabled people also use the Internet. Some Web sites are especially created for disabled people. Many Internet sites offers services for human users, but unfortunately some computer programs are designed to abuse these services. To solve this problem, some systems named CAPTCHA (completely automated public Turing test to tell computers and human apart) have been introduced to distinguish between human users and computer programs. CAPTCHA methods are mainly based on the weaknesses of OCR systems while using them is undesirable for human users, especially for disabled people. Therefore some CAPTCHA methods are designed especially for disabled people, but there is no method for peoples with more than one disability. In this paper, this problem is examined and some possible solutions are proposed.