Frontal Screens on Head-Mounted Displays to Increase Awareness of the HMD Users' State in Mixed Presence Collaboration

In the everyday context, e.g., a household, HMD users remain a part of the social life for Non-HMD users being co-located with them. Due to the social context situations arise that demand interaction between the HMD and the Non-HMD user. We focus on the challenge that the Non-HMD user is not able to interpret the HMD user's state -- e.g., attentiveness; the need for assistance --, as the HMD covers the wearer's face. We propose a front facing display attached to the HMD that supports collaboration by showing the state. We explore the impact of abstract and realistic visualizations for such displays on collaborative performance and social presence in a within-subject user study (N=25). We present to the Non-HMD user (1) a blank screen (baseline), (2) textual representation of the user's state and (3) a representation that looks like the HMD is see-through. The results show positive effects for textual representation on collaborative performance and a positive effect of realistic representation on social presence. We conclude that when developing HMDs we need to take into account the social needs of everyday life to reduce the risk of social separation in a household context.