Simulating an Extendable Tangible Slider for Eyes-Free One-Handed Interaction on Mobile Devices
In AVI '18 Proceedings of the 2018 International Conference on Advanced Visual Interfaces . pages 16:1-16:9. 2018.
Sliders are widely used on mobile devices. Envisioning mobile devices that can dynamically deform to raise tangible controls from the screen surface, tangible sliders offer the benefit of eyes-free interaction. However, reaching for distant values with one hand is problematic: users namely need to change their handgrip, which is not comfortable. To overcome this problem, this paper sets out to experimentally study an extendable tangible slider to support one-handed clutching. The tangible slider’s knob extends to maintain the thumb's movement within its comfortable area. We first built a low-fidelity prototype made of a knob long enough to allow clutching. This low-fidelity prototype significantly improves performance when reaching distant targets, as compared to a standard tangible slider. We then built a higher-fidelity prototype, introducing actuation and allowing for a shorter knob. When used for clutching, the knob moves back towards the users’ thumb. Experimental results show that the motion of the actuated knob does not interrupt eyes-free interaction during manipulation. In comparison, a graphical extendable slider performed 0.9s slower due to the required visual attention. However, the results suggest that the motion of the actuated knob affects performance, as the higher-fidelity prototype performed 0.6s slower than the low-fidelity prototype.