Should I Interrupt or Not?: Understanding Interruptions in Head-Mounted Display Settings

Head-mounted displays (HMDs) are being used for VR and AR applications and increasingly permeate our everyday life. At the same time, a detailed understanding of interruptions in settings where people wearing an HMD (HMD user) and people not wearing an HMD (bystander) is missing. We investigate (a) whether bystanders are capable of identifying when HMD users switch tasks by observing their gestures, and hence exploit opportune moments for interruptions, and (b) which strategies bystanders employ. In a lab study (N=64) we found that bystanders are able to successfully identify both task switches (83%) and tasks (77%) within only a few seconds of the task switch. Furthermore, we identified interruption strategies of bystanders. From our results we derive implications meant to support designers and practitioners in building HMD applications that are used in a co-located collaborative setting.