NavTap: a long term study with excluded blind users

ABSTRACT

NavTap is a navigational method that enables blind users to input text in a mobile device by reducing the associated cognitive load.

In this paper, we present studies that go beyond a laboratorial setting, exploring the methods' effectiveness and learnability as well as its influence on the users' daily lives. Eight blind users participated in designing the prototype (3 weeks) while five took part in the studies along 16 more weeks. Results gathered in controlled weekly sessions and real life usage logs enabled us to better understand NavTap's advantages and limitations. The method revealed itself both as easy to learn and improve. Indeed, users were able to better control their mobile devices to send SMS and use other tasks that require text input such as managing a phonebook, from day one, in real-life settings.

While individual user profiles play an important role in determining their evolution, even less capable users (with age-induced impairments or cognitive difficulties), were able to perform the assigned tasks (sms, directory) both in the laboratory and in everyday use, showing continuous improvement to their skills. According to interviews, none were able to input text before. Nav-Tap dramatically changed their relation with mobile devices and noticeably improved their social interaction capabilities.

References

1. T. Guerreiro et al. Navtap and brailletap: Non-visual input interfaces. In Rehabilitation Engineering and Assistive Technology Society of North America Conference, June 2008.
2. T. Guerreiro et al. From tapping to touching: Making touch screens accessible to blind users. IEEE MultiMedia, 15(4):48--50, 2008.
3. S. K. Kane et al. Slide rule: making mobile touch screens accessible to blind people using multi-touch interaction techniques. In Proceedings of the 10th international ACM SIGACCESS conference on Computers and accessibility, pages 73--80. ACM, 2008.
4. P. Lagoa et al. BloNo: A New Mobile Text-Entry Interface for the Visually Impaired. Springer, 2007.
5. I. S. MacKenzie and K. Tanaka-Ishii. Text Entry Systems: Mobility, Accessibility, Universality. Morgan Kaufmann Publishers Inc., 2007.
6. W. H. Organization. Magnitude and causes of visual impairment, 2008. Cited in 2009/05/08: http://www.who.int/mediacentre/factsheets/fs282/en/.
7. J. Raskin. The humane interface: new directions for designing interactive systems. Addison-Wesley, 2000.
8. M. Silfverberg et al. Predicting text entry speed on mobile phones. In Proceedings of the SIGCHI conference on Human factors in computing systems, pages 9--16. ACM, 2000.
9. G. Yfantidis and G. Evreinov. Adaptive blind interaction technique for touchscreens. Universal Access in the Information Society, 4(4):344--353, 2006.

Index Terms

• Hardware

  • Communication hardware, interfaces and storage

    • Sound-based input / output

• Human-centered computing

  • Human computer interaction (HCI)

    • HCI design and evaluation methods

    • Interaction devices

      • Sound-based input / output

      • Touch screens

    • Interaction paradigms

  • Interaction design

    • Interaction design process and methods

      • User centered design