Rounding for Warmth, Angling for Fluency: How Shapes, Cognitive Load, and Privacy Risk Influence App Adoption

Delving into corner shapes in interface design (i.e., circular vs. angular), we experimentally delineated two routes whereby users with strong privacy risk beliefs can be persuaded into adopting a mobile payment app through a bill-split use case. By introducing cognitive load as an ability factor and perceived privacy risk as a motivation force, this study bridges literature on user interface design with social psychology to unpack how subtle design cues impact app adoption through the lens of privacy assurance. The interplay among shapes, tasks, and user traits demonstrates the contextual efficacy of circular design to evoke social presence and the benefit of angular design to enhance processing fluency, which tap into users' affective and cognitive needs in face of privacy risks under varied cognitive demands to encourage adoption.