"It's like being gone for a second":using subjective evidence-based ethnography to understand locked smartphone use among young

Smartphone use usually refers to what happens after users unlock their devices. But a large number of smartphone interactions actually take place on the lock screen of the phone. This paper presents evidence from a mixed-methods study using a situated video-ethnography technique (SEBE) and a dataset of over 200h of first-person and interview recordings with 221 unique lock screen checks (n=41). We find eight categories contextual antecedents to locked smartphone use that influence the nature and the content of the subsequent smartphone interaction. Overall, locked smartphone use emerges as a means to structure the flow of daily activities and to balance between not getting too distracted and not experiencing fomo (the fear of missing out). It also appears as highly habitualised, which can cause over-use and disruption. Based on this analysis, we provide recommendations on how intervention and design approaches can leverage differences in context and purpose of locked smartphone use to improve user experience.