Device-to-Device Proximity: Response

The readings by Ramos et al. [1] and Kray et al. [3] explore the relationship between devices and proximity. Ramos et al. [1] introduce five systems that support cross-device interaction. There are two levels of proximity described to join devices: device to device and human to device. For example, bumping a device and placing a device on a digital table are device-to-device interactions; drawing the same stroke on two devices and entering a gesture/PIN within a small time window are human-to-device interactions. Ramos et al. [1] use Hall’s theory of proxemics to explain the meaning of distance in human-to-device interaction, but they do not define the device-to¬device proxemic zones. Kray et al. [3] introduces the idea by defining three discrete zones of interaction: the distal region (DR), outer proximity region (OPR), and inner proximity region (IPR). I would like to introduce another zone, the contact proximity region (CPR) to Kray’s definition, to support bumping [1].

An analogy can be brought to DR, OPR, and IPR. The zones can be centred on each device, or the table surface can provide the zones. This first setup is similar to everyone bringing a bucket of Lego to a table in their own piles: as the Lego is pushed towards another group, an interpretation of the gesture is to share the Lego. The latter setup is similar to a Chinese dining table where the shared foods are placed in the centre and the personal foods (not touched by others) are placed in the outer ring.

The two research groups [1,3] identify that confirmatory dialogue is necessary for proximity-based device connection. The bumping handshake can be broken simply by removing the physical device from contact, but there is no way to prevent the bumped device from “accepting” the connection. For example, if a malicious user wanted to intrude on your device, he could simply walk up and “bump you” to get access to your device. The same problem happens with the table: the user might drop his device onto the table and a malicious table could form a connection and take the user’s data. Ramos et al. address this issue using a pairing system that has to be replicated on both devices (i.e., same stroke on two devices and synchronized gesture/PIN) with the assumption that a device’s owner would refuse the pairing. The synchronization gesture, however, was not incorporated in Kray et al. prototype system leading to participant discontent.

Kray et al. [3] also identifies the need to give affordances to the user about the proximity zones, e.g., by showing the boundaries of the DR, OPR, and IPR in their user study. Borrowing from Bellotti et al. [2], the user does not know the ‘action’ that is happening although the user knows how to ‘address’ the system. It can be argued that the bumping also has two zones, but the contact boundary (contact versus non-contact) shows that the devices have ‘attention’ (i.e., they are connected) in Bellotti’s terminology.

1. Ramos, G., Hinckley, K., Wilson, A., and Sarin, R. Synchronous Gestures in Multi-Display Environments. Human-Computer Interaction 24, 1 (2009), 117.

2. Bellotti, V., Back, M., Edwards, W.K., Grinter, R.E., Henderson, A., and Lopes, C. Making sense of sensing systems: five questions for designers and researchers. Proceedings of the SIGCHI conference on Human factors in computing systems: Changing our world, changing ourselves, ACM (2002), 415-422.

3. Kray, C., Rohs, M., Hook, J., and Kratz, S. Group Coordination and Negotiation through Spatial Proximity Regions around Mobile Devices on Augmented Tabletops. 3rd IEEE International Workshop on Horizontal Interactive Human Computer Systems, 2008. TABLETOP 2008, (2008), 1–8.