Securing Personal Space in the Crowd: Physical Crowdedness and Organic Mobile Usage

Public transit is a major setting in which individuals spend time on smartphones, yet relatively little is known about how contextual factors in transit environments are associated with mobile usage. In this study, we examine how physical crowdedness is related to organic (self-initiated) smartphone use and how this relationship varies across usage types, individuals, and contexts. We draw on Personal Space Invasion Theory (PSIT) as a conceptual lens to organize potential behavioral responses to crowded environments, emphasizing a sequence involving arousal, attribution, and compensatory behavior. Using detailed mobile usage data from over 200,000 individuals commuting on a major subway system in Qingdao, China, we document systematic associations between crowdedness and organic mobile usage. In particular, crowdedness is positively associated with overall usage, with stronger relationships for social functionalities, among users with shorter prior trips, during off-peak periods, and when individuals are surrounded by different-age groups. To complement the observational analysis, we conduct an online survey with a randomized design, which provides supportive evidence on how crowded environments are perceived and how such perceptions are associated with usage intentions. By shifting the focus from promotion-induced behavior to organic mobile usage, this study provides new empirical evidence on how everyday environmental conditions are associated with digital engagement, and highlights rich heterogeneity in these relationships across contexts.