Interaction dialog design for the use of mobile devices while walking

A study was carried out to determine an optimal solution for presenting multiple interaction options on the limited space of a mobile device, e.g., a smartphone, taking into account the special situation of walking. We compared three different hierarchy models and a complex interaction editor which combines all the required interaction alternatives in one screen. Slow versus fast walking on a treadmill was introduced as an additional mobility condition. The results showed that menus with a hierarchy breadth of 4 or 8 to be suit best for walking. Flat hierarchies required longer time on task and led to fewer gaze changes per single interaction. The complex interaction editor triggered a high error count and a high task load level and therefore should be avoided while walking.