Hover or Tap? Supporting Pen-based Menu Navigation for Older Adults
Karyn Moffatt, Sandra Yuen, Joanna McGrenere · 2008 · Proceedings of the 10th International ACM SIGACCESS Conference on Computers and Accessibility (Assets '08) · doi:10.1145/1414471.1414483
Summary
This paper investigates "drifting" — an error specific to pen-based (Tablet PC) interaction where users accidentally hover over an adjacent menu head, causing their intended menu to close and the wrong one to open. This occurs because inductive pen technology tracks the pen position even when not touching the screen (the "hover" or "tracking" state), and hover-switching between menus is enabled by default. Older adults are disproportionately affected: in a prior study, 35 of 36 participants drifted at least once, trial time nearly doubled when drifting occurred, and older participants drifted significantly more than younger ones. The problem is compounded by hand occlusion — users lift the pen to read menu contents, inadvertently moving it over adjacent menus. Windows XP Tablet PC Edition further obscures drifts by right-aligning menus for right-handed users, causing leftmost menus to appear in the same screen location regardless of which menu is open. The authors propose two solutions: "tap" (disabling hover-switching entirely, requiring an explicit tap to change menus) and "glide" (adding a 20-pixel distance threshold before a menu switch activates, based on prior data showing 80% of drifts were under 10 pixels into the adjacent menu).
Key findings
A controlled experiment with 24 participants (12 younger aged 19-25, 12 older aged 65-85) compared tap, glide, and a control interface. Each participant completed 648 menu selection trials across all three conditions. Tap significantly reduced extra target menu invocations (the drifting measure) for both age groups — older group: F(2,12)=12.0, p=0.001, large effect size eta-squared=0.667; younger group: F(2,12)=5.94, p=0.016. Tap also showed a trend toward faster performance for older users. Glide, surprisingly, showed no performance improvement over the control for either group. Subjectively, the age groups diverged sharply: older adults rated tap as most preferred (p=0.009), fastest (p=0.010), least frustrating (p=0.003), and easiest initially (p=0.022). Younger adults, despite benefiting from tap objectively, perceived it as the slowest (p=0.037) and 7 of 12 ranked it least preferred. No accuracy differences were found between conditions. The authors suggest that hover-switching could be offered as a configurable option rather than a default, and that systems could potentially detect drifting behaviour automatically and offer to disable hover-switching.
Relevance
This paper illustrates a broader principle in accessible interaction design: features designed for efficiency (like hover-switching) can create barriers for users with reduced motor control, including older adults. The finding that younger and older users had opposite subjective reactions to the same objectively beneficial interface change underscores the critical importance of testing across age groups and supporting personalisation. For practitioners, the paper provides concrete evidence that hover-based interactions on pen and touch devices should not be the sole method of invocation — explicit tap/click alternatives must always be available. The discussion of hand occlusion as an accessibility barrier is particularly relevant to modern touchscreen design, where finger occlusion creates similar problems. The observation that users were largely unaware of why the wrong menu opened highlights how interaction errors that seem minor to designers can be deeply confusing to users, especially when occlusion prevents them from seeing the cause.
Tags: aging · input methods · touchscreen accessibility · inclusive design · user interface design · motor accessibility · pen input · older adults · menu design