Social display...We can see what you are doing on your mobile device

Mobile devices have become powerful in terms of computing and supporting various human activities. People have moved some of their activities that earlier have been done with dedicated artifacts to mobile devices. However, due to the rather private and personal interfaces of mobile devices, activities that earlier were easily observable by surrounding others have become private, decreasing the surroundings people's awareness of a mobile user's activity and thus the possibilities for serendipitous interactions. We developed a prototype called social display; it provides light-weight visual cues about mobile user's current activity with the device. The cues are displayed on a display attached to the backside of the user's mobile device. We present the concept, explain the design decisions and briefly report key findings from, first, a focus group study and, second, a field trial study.