Empirical Grounding for the Interpretations of Natural User Interface: A Case Study on Smartpen.

The emergence of Natural User Interface (NUI) approximately two decades ago promised to support intuitive and multimodal interactions by leveraging human sensorimotor skills such as touching, speaking, and gazing. Despite the development and introduction of commercial NUI hardware, traditional user interfaces (e.g., GUIs) continue to dominate in many sectors, prompting inquiry into the claims of ‘naturalness’. To examine this phenomenon, we investigated empirically two interpretations of naturalness: innateness and intuitiveness. The study involved asking 56 participants to complete learning tasks with a smartpen system and a laptop system representing innateness and intuitiveness, respectively. A mixed-method design was implemented to collect participants’ perception and performance while using both interfaces. Results indicated that, despite the smartpen system was highly learnable, the perception of naturalness was significantly linked to participants’ prior experiences rather than to innate abilities. The implications of these findings are discussed.