"Those look similar!" issues in automating gesture design advice

Today, state-of-the-art user interfaces often include new interaction technologies, such as speech recognition, computer vision, or gesture recognition. Unfortunately, these technologies are difficult for most interface designers to incorporate into their interfaces, and traditional tools do not help designers with these technologies. One such technology is pen gestures, which are valuable as a powerful pen-based interaction technique, but are difficult to design well. We developed an interface design tool that uses unsolicited advice to help designers of pen-based user interfaces create pen gestures. Specifically, the tool warns designers when their gestures will be perceived to be similar and advises designers how to make their gestures less similar. We believe that the issues we encountered while designing an interface for advice and implementing this advice will reappear in design tools for other novel input technologies, such as hand and body gestures.