Channel Switching and Adaptive Behaviors in Multichannel Communication

People often use multiple communication apps concurrently for messaging, yet how they use these channels together and the motivations for switching between them remain underexplored. To investigate this, we conducted a two-week diary study followed by interviews (N=17), examining channel-switching practices and the management of social boundaries. Our findings reveal that users switch between multiple communication channels with the same contacts, driven by factors such as different topics, expectations for fast or slow communication rhythm, specific features suited to the situation, and app-specific vibes that match their mood at the moment. Additionally, we identify inertia, where users tend to stay on the app where the last interaction occurred, as the opposite of active channel switching. Our findings show that users do not actively distinguish apps based on relationships. Instead, their contacts are dispersed across different communication apps due to adaptive behaviors. These behaviors include users continually adapting to unique relationships, evolving communication needs, and app changes over time. Based on these insights, we propose design implications for multichannel communication to help users manage cross-app communication flows effectively.