Tablet PCs are gaining popularity, but many individuals still struggle with pen-based interaction. In a previous baseline study, we examined the types of difficulties younger and older adults encounter when using pen-based input. The research reported in this article seeks to address one of these errors, namely, missing just below. This error occurs in a menu selection task when a user.s selection pattern is downwardly shifted, such that the top edge of the menu item below the target is selected relatively often, while the corresponding top edge of the target itself is seldom selected. We developed two approaches for addressing missing just below errors: reassigning selections along the top edge and deactivating them. In a laboratory evaluation, only the deactivated edge approach showed promise overall. Further analysis of our data revealed that individual differences played a large role in our results and identified a new source of selection difficulty. Specifically, we observed two error-prone groups of users: the low hitters, who, like participants in the baseline study, made missing just below errors, and the high hitters, who, in contrast, had difficulty with errors on the item above. All but one of the older participants fell into one of these error-prone groups, reinforcing that older users do need better support for selecting menu items with a pen. Preliminary analysis of the performance data suggests both of our approaches were beneficial for the low hitters, but that additional techniques are needed to meet the needs of the high hitters and to address the challenge of supporting both groups in a single interface.


Paper [PDF]  [ACM]  [BIB]

© ACM, 2009. This is the author's version of the work. It is posted here by permission of ACM for your personal use. Not for redistribution.