Fingers and Angles

Smartwatches present a unique touch input context: small, fixed to one wrist and approachable from a limited range of angles by the touching hand. Techniques to expand their input expressivity often involve variations in how a watch must be touched, such as with different fingers, poses or from specific angles. While objective performance with such systems is commonly reported, subjective qualities such as comfort remain overlooked. We argue that techniques that involve uncomfortable input will be of limited value and contribute the first data on the comfort of input on smartwatches via two studies that combine subjective ratings of comfort with objective performance data. We examine both static and dynamic touches and three finger poses. Based on the study results, we contribute a set of design recommendations for comfortable, effective smartwatch input. We close by instantiating the recommendations in interface prototypes that we evaluate in a final qualitative study.