What Can I Say?: Effects of Discoverability in VUIs on Task Performance and User Experience

Kirschthaler, Philipp; Porcheron, Martin; Fischer, Joel E.

Abstract

Discoverability, the ability for users to find and execute features through a user interface, is a recurrent problem with Voice User Interface (VUI) design that makes it difficult for users to understand what commands are supported by a newly encountered system. We studied the effects of two different discoverability strategies proposed in literature, one which provides informational prompts \textit{automatically} and one which provides help only when the user \textit{requests} it by asking `What Can I Say?'. Our study adopted a Wizard of Oz approach that allowed users to order food delivery by voice. Through statistical analysis, we confirmed the beneficial nature of both discoverability strategies, with significantly better task performance and higher self-reported usability scores in comparison to a baseline. This suggests designers should consider the use of a discoverability strategy in the design of VUIs. While no significant differences were found between the strategies, a majority of the participants highlighted their preference for the `What Can I Say?' strategy if they were to use the VUI more frequently. Finally, we reflect on the implications for the design of VUIs, highlighting the need to distinguish between initial use and longer-term use in the selection of a discoverability strategy.

Citation

Kirschthaler, P., Porcheron, M., & Fischer, J. E. (2020). What Can I Say?: Effects of Discoverability in VUIs on Task Performance and User Experience. In CUI '20: Proceedings of the 2nd Conference on Conversational User Interfaces. https://doi.org/10.1145/3405755.3406119

• Conference Name: CUI '20: 2nd Conference on Conversational User Interfaces
• Start Date: Jul 22, 2020
• End Date: Jul 24, 2020
• Acceptance Date: Jun 10, 2020
• Online Publication Date: Jul 13, 2020
• Publication Date: Jul 22, 2020
• Deposit Date: Jun 12, 2020
• Publicly Available Date: Jul 13, 2020
• Publisher: Association for Computing Machinery (ACM)
• Book Title: CUI '20: Proceedings of the 2nd Conference on Conversational User Interfaces
• ISBN: 9781450375443
• DOI: https://doi.org/10.1145/3405755.3406119
• Keywords: Voice interfaces, Conversational interfaces, Dialogue design, Discoverability, Learnability, Wizard of oz, Usability, User study
• Public URL: https://nottingham-repository.worktribe.com/output/4632840
• Publisher URL: https://dl.acm.org/doi/10.1145/3405755.3406119
• Related Public URLs: https://cui2020.com/
• Additional Information: Article no. 9.