¶ … Computer Science Research on Alternatives to Visual-Based CAPTCHAs for Sight-Impaired Users

Created to block the Web bots used by spammers, CAPTCHA ("Completely Automated Public Turing Test to Tell Computers and Humans Apart") is a technology used to verify that a person, rather than an automated system, is entering the data. A visual-based CAPTCHA shows distorted text and then users type in what they see in order to proceed. Users encounter CAPTCHAs in a variety of different Internet activities, such as submitting online comments and forms, creating email accounts, and registering for networking sites [1].

Because CAPTCHAs cannot be read by machines, the screen-reading software used by blind computer users cannot read the text either [2], which leaves these people unable to use the Web sites. This paper reviews the literature on CAPTCHA alternatives for blind and sight-impaired users.

This CAPTCHA displays an image of an object along with the sound it makes, allowing users to indentify it using either their eyesight or hearing [3]. The researchers tested on five blind users and five sighted users, and all five of the blind users made at least one error but were eventually able to enter in the correct terms [3]. The methodology is clearly presented, but a small test group is a limitation of the study.
In Spoken Captcha: A Captcha System for Blind Users, the authors propose using a sound clip, with the user responding with the matching word [4]. A speech file of the user's voice is created, and the system then checks to ensure the word matches and to verify that the voice is not…