  Little research has investigated the design of conversational styles of voice
assistants (VA) for adults in their later adulthood with varying personalities.
In this Wizard of Oz experiment, 34 middle-aged (50 to 64 years old) and 24
older adults (65 to 80 years old) participated in a user study at a simulated
home, interacting with a VA using either formal or informal language. Older
adults with higher agreeableness perceived VA as being more likeable than
middle-aged adults. Middle-aged adults showed similar technology acceptance
toward the informal and formal VA, and older adults preferred using informal
VA, especially those with low agreeableness. Further, while both middle-aged
and older adults frequently anthropomorphized VAs by using human metaphors for
them, older adults compared formal VA with professionals (e.g., librarians,
teachers) and informal VA with their close ones (e.g., spouses, relatives).
Overall, the conversational style showed differential effects on the
perceptions of middle-aged and older adults, suggesting personalized design
implications.
