Hinge Gestures: Leveraging Foldable Phone Hinges to Enrich Dual-Screen Tactile Interaction

Foldable phones naturally support displaying two applications side by side on adjacent screens. However, one-handed interaction with this dual-screen configuration faces two challenges: first, users must change grip to reach each screen; second, menus displayed on each screen take valuable screen real estate and can be difficult to reach. To address this, we investigated how the hinge of foldable phones can enrich tactile interaction and provide access to hinge menus, unifying interaction across both screens. In a first experiment, we examined how users hold a foldable phone at different fold angles and identified the thumb-accessible screen areas, validating that a hinge-based grip enhances reachability. In two subsequent experiments, we evaluated the feasibility and performance of hinge gestures, defined as touch inputs (tap, tap-tap or swipe) executed fully or partially on the hinge. Building on these findings, we designed hinge menus that combine hinge gestures for menu activation and item selection. Our final experiment identifies different hinge menus that outperform linear menus on adjacent screens. Our findings provide practical guidelines that can immediately inform and improve interaction on current foldable phones.