Beyond Usability: A UX Case Study on Using "Withdrawal Design" to Challenge Engagement Metrics in Social Robotics

Abstract

Social robots for children with autism are often evaluated through engagement and interaction quality, assuming the robot acts as a social scaffold. We report a mixed-methods "withdrawal" study that tests a harder question: what changes when the robot is removed. In an 8-week home-based randomized controlled trial (N=40), children either retained a consumer social robot (Qrobot) or had it withdrawn after initial use. Quantitatively, continued access reduced anxiety (SCARED/RCADS), yet was associated with lower parent-reported social motivation and weaker gains in emotion recognition (SMS/RMET) compared to withdrawal. Interviews with guardians contextualized this divergence: removal sometimes prompted children to seek human interaction, while continued use could keep social behavior siloed within the child-robot dyad, despite exceptionally high usability (SUS). We synthesize a UXR point of view: for vulnerable users, "engagement" can mask ecological downsides. Success should be judged not by retention, but by designed separation that bridges back to human relationships.