Palmrest+: Expanding Laptop Input Space with Shear Force on Palm-Resting Area

The palmrest area of laptops has the potential as an additional input space, considering its consistent palm contact during keyboard interaction. We propose Palmrest+, leveraging shear force exerted on the palmrest area. We suggest two input techniques: Palmrest Shortcut, for instant shortcut execution, and Palmrest Joystick, for continuous value input. These allow seamless and subtle input amidst keyboard typing. Evaluation of Palmrest Shortcut against conventional keyboard shortcuts revealed faster performance for applying shear force in unimanual and bimanual-manner with a significant reduction in gaze shifting. Additionally, the assessment of Palmrest Joystick against the laptop touchpad demonstrated comparable performance in selecting one- and two- dimensional targets with low-precision pointing, i.e., for short distances and large target sizes. The maximal hand displacement significantly decreased for both Palmrest Shortcut and Palmrest Joystick compared to conventional methods. These findings verify the feasibility and effectiveness of leveraging the palmrest area as an additional input space on laptops, offering promising enhanced typing-related user interaction experiences.