Examining Humanness as a Metaphor to Design Voice User Interfaces

TL;DR

This study investigates whether humanness as a design metaphor shapes user perceptions of VUIs differently in health and finance domains, and whether explicit versus implicit awareness of the metaphor changes adoption tendencies. Using a $2\times4$ mixed design with four metaphor conditions (doctor, health encyclopedia, financial advisor, calculator) and 240 participants, the authors crafted controlled dialogues delivered via text-to-speech to measure enjoyment, adoption intent, trust, likeability, and perceived intelligence. Key findings show that in health, human metaphors boost enjoyment and likeability, while in finance there is no strong difference between human and non-human metaphors; trust is modestly higher for human metaphors overall, and an awareness-by-metaphor interaction can influence adoption intentions for non-human metaphors. The paper concludes with three design guidelines—tailor metaphors to domain sensitivity, avoid over-reliance on explicit signaling, and make metaphor usage context-aware—arguing for a flexible design space that can improve engagement and adoption of non-human metaphors in VUIs.

Abstract

Voice User Interfaces (VUIs) increasingly leverage 'humanness' as a foundational design metaphor, adopting roles like 'assistants,' 'teachers,' and 'secretaries' to foster natural interactions. Yet, this approach can sometimes misalign user trust and reinforce societal stereotypes, leading to socio-technical challenges that might impede long-term engagement. This paper explores an alternative approach to navigate these challenges-incorporating non-human metaphors in VUI design. We report on a study with 240 participants examining the effects of human versus non-human metaphors on user perceptions within health and finance domains. Results indicate a preference for the human metaphor (doctor) over the non-human (health encyclopedia) in health contexts for its perceived enjoyability and likeability. In finance, however, user perceptions do not significantly differ between human (financial advisor) and non-human (calculator) metaphors. Importantly, our research reveals that the explicit awareness of a metaphor's use influences adoption intentions, with a marked preference for non-human metaphors when their metaphorical nature is not disclosed. These findings highlight context-specific conversation design strategies required in integrating non-human metaphors into VUI design, suggesting tradeoffs and design considerations that could enhance user engagement and adoption.

Figures (5)

• Figure 1: Boxplots indicating the distribution of perceived enjoyment scores for human and non-human metaphors across health, finance, and overall.
• Figure 2: Boxplots indicating the distribution of perceived intention to adopt scores for human and non-human metaphors across health, finance, and overall.
• Figure 3: Boxplots indicating the distribution of trust scores for human and non-human metaphors across health, finance, and overall.
• Figure 4: Boxplots indicating the distribution of likeability scores for human and non-human metaphors across health, finance, and overall.
• Figure 5: Boxplots indicating the distribution of perceived intelligence scores for human and non-human metaphors across health, finance, and overall.