Structure Over Color: Eye-Tracking Evidence on Navigation Depth and Elderly Users’ Online Trust in Health Apps

As populations age, digital health platforms play a critical role in supporting elderly users’ access to health information. However, the interface remains a decisive factor shaping users’ trust and engagement. This study investigates how navigation depth and interface color jointly influence elderly users’ online trust and visual search behavior.treeA2 (navigation structure: flat vs. tree)×3 (color: red, green, blue) within-subjects experiment was conducted with older adults, combining an online trust scale and eyetracking measures. The findings show that navigation depth exerts a stronger influence on trust perception and search efficiency than color, with the flat structure consistently outperforming the tree structure. While color had a modest effect, blue interfaces facilitated more efficient visual exploration than red or green. These results highlight that structural simplicity outweighs color cues in shaping elderly users’ trust, offering empirical evidence and design implications for developing accessible and trustworthy health applications for aging populations.