Table 3:

The seven design principles from Ability-based design [87, 88] (and additional Privacy and Trust considerations) and how they have been mapped to older adults’ needs from our analysis.

	Principle	Definition	Design Strategies to Support Older Adults Access Voice-based IVAs	Barriers
Stance	Ability	Designers will focus on ability not dis-ability, striving to leverage all that users can do to augment what users need to do.	Older adults could ubiquitously interact with PPs through IVA, especially the tasks need be completed periodically and do not require much time and efforts, e.g., EMA;	B-A1, B-A2, B-C1, B-C3, B-D3
			The system should also allow providers to easily change IVA configurations based on patients’ need (e.g., enable/disable the IVA connected to a specific features on PPs).
			Visual output could be beneficial for better social interaction experience and ease-of-use;	B-B1, B-C3
			Multimodal output could be beneficial for those with sensory impairment;	B-D2
	Accountability	Designers will respond to poor performance by changing systems, not users, leaving users as they are.	IVA needs to correctly understand older adults’ intent and offer mechanism to repair interaction upon failures;
Interface	Adaptation	Interfaces may be self-adaptive or user-adaptable to provide best possible match to users’ desire and ability.	Personalized chat should be based on older adults’ hobbies and interests;	B-B1
			It might be beneficial to design personalized proactive health advice on-demand;	B-A1, B-A2, B-B2, B-B3
	Transparency	Interfaces may give users awareness of adaptations and the means to inspect, override, discard, revert, store, retrieve, preview, and test those adaptations.	Older adults should have clear and explicit guidance during device setting up and troubleshooting phases;	B-D1
System	Performance	Systems may regard users’ performance, and may monitor, measure, model, or predict that performance.	IVA need to sense and understand the context of the older adults’ life;	B-A1, B-B2, B-B3
	Context	Systems may also proactively sense context and anticipant its effect on users’ ability.	Older adults can control their home environment through IVA;	B –B3
	Commodity	System may comprise low cost, inexpensive, readily available commodity hardware and software.	The integration of IVA into existing technologies should not incur significate increasing on the cost;	B-A1, B-A2
	Privacy and Trust	Systems may comprise low-cost, readily available commodity hardware and software. System may also need to be secure enough where users can establish trust with it.	Countermeasures might be required to ensure confidentiality of unintended speech and contextual data, as well as establish trust between older adults and device;	B-D4