 they also shared three perceived barriers to VR for intergenerational communication. One prominent barrier was the overhead of initiating communication in VR (N=16) especially compared to other media, as one participant (F11, GS) explained: \textit{``We can chat via phone call by simply turning on the phone and dialing. But to communicate in VR, we have to first find a physical space, wear the headset, and set up the application before we can meet...''}
 Despite the overhead of using VR, it was still perceived to be more appealing than video calls because it could provide a sense of togetherness and relieve nostalgia, especially for grandparents and grandchildren who have separated for a long time (e.g., grandchildren who went abroad for school). One participant (F9, GM) elaborated: \textit{``[In VR] I felt like I was sitting and chatting with her face to face. It's amazing... I hope to use it to contact my family members living far away from me''}. }
 
 The second barrier was the perceived difficulty of the operations of VR controllers, especially for grandparent participants (N=8).
 Many grandparent participants found some operations (e.g., pushing the ``A'' button to navigate) non-intuitive and difficult to learn and thus had to spend more energy and attention learning such operations, which made them nervous and distracted them from communicating with their grandchildren. However, grandparent participants were receptive to the operations that simulate their familiar actions in real life, such as swinging the controller to hit the ball and clapping the other's hands. During the VR experiences, grandparents (N=10) asked their grandchildren for help via voice in VR, and their grandchildren often patiently taught the grandparents how to operate the hand-controller to operate.

 
 \rv{The last barrier was related to safety concerns (N=5). Many participants worried that they might bump into surrounding objects and fall because VR headsets covered their faces and blocked their sight. They pointed out that this might be particularly dangerous to older adults who live alone, as one participant (F12, GS) explained: \textit{``I'm worried about letting her use VR at home alone because I can't help her if she falls.''} The VR headset we used (Quest2) allowed users to define the ``play area'', which shows a virtual fence and reveals the real surroundings to the VR user if she steps out of this area. However, participants still felt it insufficient and hoped to check their surroundings from time to time as such a ``play area'' cannot reveal moving objects, such as smart vacuum cleaners that move around. Consequently, participants felt that they would only be comfortable using VR if safety concerns are out of the way.}

 \sout{\textbf{Demographic Factors that Affect VR Experiences between Grandparents and Grandchildren}}

 \sout{According to our study, several factors affect participants' perceptions of VR-based remote communication, such as in-person meeting frequency, the closeness between grandparents and grandchildren, the gender of the grandparent, and the health condition of the grandparent.}

 

 \sout{We found that the \textit{in-person meeting frequency} affected their willingness to use VR for remote communication: the fewer in-person meeting frequency and the longer of separation, the more they want to communicate using VR. }


 Because of its simplicity and familiarity, they tended to use phone calls to contact each other when the separation first arises. However, for those who have separated for a long time (e.g., grandchildren who went abroad for school), VR became more appealing because the sense of co-presence and togetherness brought by VR could relieve their nostalgia. 
 
 \sout{\textit{The closeness between grandparents and grandchildren.} We measured the closeness between grandparents and grandchildren using the frequency of remote communication and the length of time they lived together~\cite{geurts2012grandparent, viguer2010grandparent}. Although all participants were cheerful and excited when communicating in VR, the grandparents and grandchildren who had closer connections exhibited a higher acceptance of VR as their remote communication tool in the future. The grandparents and grandchildren with weaker bonds thought communicating in VR with each other was more burdensome.}
 
 \sout{Different \textit{gender of grandparents} may play different roles in the grandparent-grandchild relationship \cite{kennedy1992shared, sheehan2008grandparents}, which affect their favorite VR activities. Participants who were grandfathers tended to share stories from their youth through VR activities, hoping that their grandchildren would learn some knowledge and lessons. Participants who were grandmothers preferred to have a family meeting or travel in VR, enjoying the happiness of chatting together with family members.}

 \sout{\textit{Health condition of the grandparent.} Our results showed that elderly participants with poor health were more likely to accept VR. Two of our older participants had difficulty walking, and had not traveled for a long time. They appreciated the immersion brought by VR, which made them feel like they actually visited different places, and enabled them to visit their grandchildren ``physically''. They felt more cheerful and excited in VR than the healthy participants.}




 


 

 

 



 



 

\section{Discussion}

\rv{We investigated how VR could be leveraged and designed to facilitate inter-generational communication between grandparents and grandchildren through a participatory design study in which participants interacted with each other in VR and designed features to show how they would want VR to be designed to facilitate their communication. Our findings show that 1) participants chose different types of avatars to satisfy different communication needs; 2) interpersonal interactions via embodied avatars, especially those that have intimate physical contact or are considered ``inappropriate'' between grandparents and grandchildren in real life, could facilitate inter-generational communication; 3) participants felt that engaging in shared activities allowed them to find more topics to fill in the silence in conversations and further envisioned three types of shared activities they wanted to engage in; 4) participants also perceived three main barriers of adopting VR for inter-generational communication: overhead of setting up VR for communication, perceived difficulty of certain VR operations, and safety concerns.  
In this section, we further discuss the design implications of our findings and related future research agenda for better leveraging VR to facilitate inter-generational communication between grandparents and grandchildren. }


\sout{\textbf{Role of VR for Grandparent-grandchild relationship} }

 \sout{We identified two roles VR played in remote inter-generational communication based on the findings, which are \textit{communication facilitator} and \textit{nostalgia reliever}.}
 
 
 \sout{Results show that VR acted as a \textit{communication facilitator} in three ways: allowing  \textit{the customization of avatars}, providing\textit{shared activities}, and offering \textit{a wide variety of non-verbal language}.  First, VR enabled participants to use abstract avatars, which encouraged grandchildren to talk and physically interact with their grandparents more casually and frequently. Thus, VR made grandchildren feel more equal with their grandparents by reducing age-related power imbalance.
 Second, through engaging in shared activities provided by VR, grandparents and grandchildren gained more fun and exchanged their thoughts and emotions more easily than only speaking. Additionally, shared activities helped fill in the inevitable silence during conversation and provided more opportunities to strike more conversations.
 Third, VR enriched communication by offering a wide variety of non-verbal language, enabling participants to express themselves more effectively.}
 
 \sout{VR also acted as the \textit{nostalgia reliever} for remote grandparents and grandchildren to alleviate their feelings of nostalgia, especially for those who have been separated for a long time. \textit{The simulated physical interactions} enabled remote users to touch each other, while \textit{co-presence} provided a sense of intimacy despite the long distance between them in real life. Additionally, the emerging techniques of real-time 3D reconstruction \cite{orts2016holoportation, izadi2011kinectfusion, newcombe2015dynamicfusion} may allow grandparents and grandchildren to use realistic avatars. Therefore, remote grandparents and grandchildren could interact in the same virtual room with real faces to show their well-being and physical health, which participants believed can satisfy their longingness for the other.}
 
 \sout{Overall, combined with previous research indicating that using VR for communication can improve the quality of life for older adults and their remote families~\cite{afifi2022using}, our results show that VR is a viable communication media for remote grandparents and grandchildren by supporting the need of communication and relieve nostalgia. }

 \sout{\textbf{The Uniqueness of VR Communication for Grandparent-grandchild Relationships}}
 
 \sout{As discussed in Section 2, no prior work investigated remote communication in VR for grandparent-grandchild relationships. Our work uncovered the uniqueness of VR communication in a grandparent-grandchild relationship compared to other relationships (e.g., friends, couples, or strangers) by revealing several differences between these contexts.}

 \sout{Although the pros and cons of VR in communication may be applicable to a wide range of people, they contained nuanced differences for specific types of relationships. }
 \sout{For \textit{the customization of the avatar}, abstract avatars in different relationships made participants feel relaxed and cheerful during conversation~\cite{baker2021avatar, Li2019, maloney2020virtual}, while it played a specific role in reducing the age-related power imbalance for grandparent-grandchildren relationships. In contrast, when communicating with strangers, people enjoyed the sense of anonymity of the avatar and felt encouraged to have more social interactions with others~\cite{baker2021avatar, kang2013impact}.  For \textit{the feeling of co-presence and simulated physical interactions}, grandparents and grandchildren