Getting off the treadmill: evaluating walking user interfaces for mobile devices in public spaces

Using a mobile device while moving limits attention and motor ability and can result in reduced performance. Mobile devices that can sense and adapt to contextual factors such as movement may reduce this performance deficit. We performed two studies evaluating the feasibility of walking user interfaces (WUIs) that adapt their layout when the user is moving. In a pilot study with 6 users, we evaluated the effects of different button sizes on performance when walking while using a portable music player. Results showed significant interactions between size and movement. In the second study, 29 users evaluated the performance of a WUI that dynamically changed button sizes as the user moved. Results show that our dynamic user interface performs at the level of its component static interfaces without any additional penalty due to adaptation. This work adds to our design knowledge about walking user interfaces and provides lessons learned in evaluating mobile devices while walking in public spaces.