Objective: This study aims to analyze the differences in mobile application usability across age groups and modality conditions, focusing on how older and younger users perform and perceive tasks under different information presentation formats.

Background: As mobile applications have become essential in daily life, most services are designed with visual information and touch-based interaction, which can increase cognitive workload for older users with cognitive declines. Previous studies have highlighted the importance of age-sensitive mobile application design but have focused on either specific age groups or limited modality types. There is a need for integrated analysis that compares usability across age groups and different information presentation modalities.

Method: This study evaluated usability differences between younger and older adults in mobile application tasks under four modality conditions, defined by a combination of information presentation (visual only vs. visual plus auditory) and help function availability (with vs. without help). A total of 40 participants (20 younger, 20 older adults) performed 12 trials involving three mobile application tasks—shopping, food ordering, and banking. Performance was assessed using objective measures (Completion time, Error count) and subjective workload (NASA-TLX).

Results: Older adults exhibited significantly longer completion times, higher error rates, and greater perceived workload across all tasks compared to younger adults. Main effects of age indicated lower usability for older users, particularly in completion time, errors, and effort. Modality conditions that combined auditory feedback with help functions significantly reduced errors and workload, especially for older adults. Significant age × modality interactions were found in error rates and performance, with older adults benefiting most from help-supported modalities.

Conclusion: Multimodal support and help functions improved usability for older adults. Designing interfaces that reduce cognitive load can enhance mobile accessibility and user experience for older adults.

Application: This study contributes to universal design by presenting effective strategies to reduce cognitive load and enhance mobile application accessibility for older users.