Document Type



This item is available under a Creative Commons License for non-commercial use only


Computer Sciences, Information Science

Publication Details

A dissertation submitted in partial fulfilment of the requirements of Technological University Dublin for the degree of M.Sc. in Computing(Assistive Technology) July 2012.


In the computing domain the relationship between accessibility and security is a complex and evolving one; accessibility attempts to ensure that as wide a range of individuals as possible are granted access to systems, whereas security attempts to restrict access only to individuals who are entitled to access those systems. A key security concern is to determine whether or not the system is being accessed by a software agent or a real human being, and a number of approaches have been developed to determine the answer to this question. This issue has been discussed throughout the history of computer science and its roots can be traced back to Alan Turing's 1950 paper "Computing Machinery and Intelligence" from which the so-called "Turing Test" derives its name. A very common approach to this question is the CAPTCHA (the "Completely Automated Public Turing test to tell Computers and Humans Apart"), which requires a human being to perform a visual test, typically recognizing alphanumeric characters that are obscured or warped in some way to make Optical Character Recognition (OCR) difficult. This seemingly effective approach highlights the essential tension between security and accessibility, since it provides significant challenges to rely on a visual character recognition test when considering users with visual impairments or learning difficulties. In this work, an accessible biometric alternative to the CAPTCHA user interface is proposed. In the event of a single sign-on biometric recognition system, the interface developed has the potential to exploit the capabilities of the iPad platform to provide universal access. The proposed interface, BioScope, is implemented using accessible development and evaluation methodologies to ensure universal and inclusive design. Following implementation, the interface is evaluated and compared with CAPTCHA using a series of surveys, questionnaires and prototype experiments with the aim of determining if BioScope’s approach