"Those Look Similar!" Issues in Automating Gesture Design Advice

Summary:

Gesture that are similar are hard to classify for a computer and difficult to remember for a user. Long and Landay created a tool called quill that helps designers improve any gestures they want to use by highlighting any gesture similarities. Designers can then take these similarities into account and redesign their gestures to be more unique.

When using quill, designers take a gesture they want implemented into their system and draw some examples into the tool. After more than one gesture class has been drawn quill begins to analyze the gestures for similarities. Similarity was determined to be based heavily upon gesture curviness and angle, as well as the density of the gesture. For more on how similarity was determined see "Visual Similarity of Pen Gestures."

The paper goes into detail about how presenting advice to the user is a large interface challenge. Long and Landay did not want quill to annoy expert gesture designers, but they also wanted to provide enough advice that both novice and experts could benefit from the system. In the end they decided to delay advice until the designer decides to test a gesture. The authors decided that designer were probably done with tweaking their initial gestures a bit when they were testing. Yet, quill also provides more subtle warnings to the designers whenever they pause.


Discussion:

Improving gesture designs by letting the computer point out when gestures might be confusing is a great way to safeguard poor gesture choices. The analysis of when to present advice to a user is also a large UI problem outside of quill; for instance, when should a stroke/symboll be beautified or when should a symbol be recognized? Long and Landay provided a good overview of their decisions, and I really liked their choice to present advice when the designer decides to test their classes.

I'm curious at how good the advice actually is for the system and how annoying it might be if the same advice keeps appearing every time I test my classes. If I design a left-to-right horizontal line to be a "Page Forward" gesture and a right-to-left horizontal line to be "Page Back" the computer might tell me that the gestures are similar, but the gestures have such a good mapping to forward and back arrows that users shouldn't confuse the two. I wouldn't want the system to constantly be warning me of this issue.