People often strive to present themselves authentically on social media, but this may not be possible for everyone. To understand how people view online authenticity, how it relates to social media sharing behaviors, and whether it is achievable, we interviewed 28 social media users who had recently experienced major life transitions. We found that to many participants, online authenticity required presenting a consistent, positive, and "true" self across online and ofine contexts. Though most stated that they considered online authenticity achievable, their social media self-disclosure behaviors around life transitions revealed what we call the online authenticity paradox: people strive to achieve online authenticity, yet because doing so requires sharing negative experiences on social media, online authenticity is often unreachable, or is possible only at great personal cost -especially for those with marginalized identities and difcult life experiences. CCS Concepts: • Human-centered computing → Empirical studies in HCI; Empirical studies in collaborative and social computing.

In August 2020, the U.S. President issued an executive order to ban the Chinese-based social platform WeChat, alleging that WeChat posed a national security risk. WeChat is a vital application for Chinese diasporic communities in the United States. The ban's status was uncertain for several months before it was temporarily halted and later revoked in 2021. Through interviews with 15 WeChat users and online participant observation, this study examines the anticipated impacts of the potential WeChat ban and participants' reactions. We find that participants described negative consequences of the potential ban, including adverse network and economic effects and disruption of community-building efforts. We also find that many participants considered WeChat to be critical infrastructure in the United States, as it has become an indispensable part of their daily lives. To frame participants' experiences, we introduce the concept of infrastructural migration-the process of users relocating to another digital media service that embodies the properties and functions of infrastructure or moving to an assemblage of different applications that meet their infrastructural needs separately. We then discuss implications for designing for infrastructural migration and future considerations for HCI research with diasporic communities.

Major life events can cause great upheaval in one's life. Many people perceive their identities to change due to major life events. During identity shifts, impression management and self-presentation, online communities, and social media affordances can allow individuals to better facilitate their experiences. To examine how people perceive their identity to change during major events and how they use social media in the process, we interviewed 28 participants who recently experienced major life events. We found that many people perceived their identity to change through various avenues that they felt were important to their identity: mental processes, identity roles, and identity fulfillment. However, some people perceive their identity to be maintained rather than changed. During identity changes or maintenance, participants utilized impression management and self-presentation to curate their online presence. Participants also used online communities to build relationships with similar others or virtual friends and enable more connections via what we call the domino effect. Social media sites also provided the affordances of editability, visibility control, and spreadability, which can help ease life transition and identity change processes.

Some life transitions can be difficult to discuss on social media, especially with networks of known ties, due to challenges such as stigmatization. Separate online networks can provide alternative spaces to discuss life transitions. To understand why and how people turn to separate networks, we interviewed 28 participants who had recently experienced life transitions. While prior research tends to focus on one life transition in isolation, this work examines social media sharing behaviors across a wide variety of life transitions. We describe how people often turn to separate networks during life transitions due to challenges faced in networks of known ties, yet encounter new challenges such as difficulty locating these networks. We describe support from waiting contributors and virtual friends. Finally, we provide insight into how online separate networks can be better designed through enhancing search functionality, promoting contribution, and providing context-sensitive templates for sharing in online spaces.

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