Paper Reading #29: Usable gestures for blind people: understanding preference and performance

References
Usable gestures for blind people: understanding preference and performance by Shaun K. Kane, Jacob O. Wobbrock, and Richard E. Ladner
 Published in the CHI '11 Proceedings of the 2011 annual conference on Human factors in computing systems.

Author Bios

• Shaun K. Kane is currently an Assistant Professor at the University of Maryland and holds a PhD from the University of Washington.
• Jacob O. Wobbrock is currently an Associate Professor at the University of Washington.
• Richard E. Ladner is currently a Professor at the University of Washington and holds a PhD in Mathematics from the University of California, Berkeley.

Summary

• Hypothesis
• Blind people have different needs and preferences for touch based gestures than sighted people.  This paper aims to explore exactly what these preferences may be.
• Methods 
• In the first study both blind and sighted people were asked to invent a few of their own gestures that might be used to interact and conduct standard tasks on a computing device.  Because visual results of commands would not be visible to all participants, the experimenter read a description of the action and result of each command.  Each participant invented two gestures for each command and then assessed them based on usability, appropriateness, etc.
• The second study was more focused on determining whether blind people simply perform gestures differently or actually prefer to use different gestures.  In this study all participants performed the same set of standardized gestures.  The experimenter described the gesture and its intended purpose, and the participants tried to replicate it based on his instruction.
• Results
• In the first study the experimenters found that, on average, a blind person's gesture contains more strokes than a sighted person's.  Additionally, blind people were also slightly more likely to make use of the edge of the tablet when positioning their gestures, as well as being more likely to use multi-touch gestures.
• In the second study, there was no significant measure of difference in easiness between blind and sighted people.  It was noted that blind people tended to make significantly larger gestures than sighted people, although the aspect ratio appeared consistent between the two groups.  Additionally, blind participants took about twice as long to perform the gestures, and their lines were often more "wavy" than those of sighted participants
• Contents
• This paper makes steps towards bridging the touch screen accessibility gap for blind people.  After discussing some of the previous work done in the field, the authors describe their two experiments designed to measure exactly how blind people's gesture preferences might be different from sighted people's.   The findings are, overall, reasonably predictable in terms of differences between area of the gesture and speed to perform, and the results suggest new design guidelines for more accessible touch interfaces.

Discussion
I thought that this was a very interesting study and I think the authors did a great job of achieving their stated goals.  They performed well-thought-out tests and presented their findings in a very convincing and organized manner.  I would like to see them expand on their work with accessibility in interfaces, perhaps focusing on other disabilities such as general motor impairment.