  Older adults have been hit disproportionally hard by the COVID-19 pandemic.
One critical way for older adults to minimize the negative impact of COVID-19
and future pandemics is to stay informed about its latest information, which
has been increasingly presented through online interactive visualizations
(e.g., live dashboards and websites). Thus, it is imperative to understand how
older adults interact with and comprehend online COVID-19 interactive
visualizations and what challenges they might encounter to make such
visualizations more accessible to older adults. We adopted a user-centered
approach by inviting older adults to interact with COVID-19 interactive
visualizations while at the same time verbalizing their thought processes using
a think-aloud protocol. By analyzing their think-aloud verbalizations, we
identified four types of thought processes representing how older adults
comprehended the visualizations and uncovered the challenges they encountered.
Furthermore, we also identified the challenges they encountered with seven
common types of interaction techniques adopted by the visualizations. Based on
the findings, we present design guidelines for making interactive
visualizations more accessible to older adults.
