Investigating the Impact of Deformable, Movable, and Rigid Surfaces on Force-Input Interactions

The force modality fundamentally transforms the interaction space of traditional touch input. When paired with compliant devices, which deform under force and provide immediate haptic feedback, there is potential to enhance user interactions significantly. However, the effects of compliance on force-input remain under-explored, with limited understanding of their full potential. This paper presents the first systematic investigation of the impact of deformable, movable, and rigid surfaces on user performance and experience through three rigorous studies (each N = 28). The results reveal previously unreported effects, including 1) higher maximum comfortable forces on deformable surfaces, 2) user preference for soft and deformable surfaces over rigid surfaces, and 3) improved ability to maintain force input on softer surfaces. These results highlight the benefits of compliant surfaces, contrasting with the dominant use of force-input on rigid devices. These findings guide researchers and designers in optimising user experience and performance of force-input interactions.