Design Patterns for Mobile User Interfaces Targeted at Older Adults

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ACTIVITY ZONES AND TOUCH OFFSETS FOR SWIPE GESTURES **

Context

… you have selected adequate gestures for all targets on your smartphone interface, and have decided on target sizes for swipe gestures, as well as on spacing sizes between adjacent tap targets. Now, you are looking for information regarding the placement of swipe targets on the smartphone’s display, in order to compensate issues related to users’ reachability of certain smartphone screen regions.

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Problem

You have a series of swipe targets that you need to distribute throughout your interface. However, not all screen regions allow for the same levels of efficiency, and accuracy in target selection.

Rationale

Activity zones are defined as the regions on the smartphone’s display that are more easily reachable, and therefore allow for better performance measures. Several authors have investigated activity zones for tap targets on mobile touchscreen devices with younger adults (Henze, Rukzio, & Boll, 2011; Parhi, Karlson, & Bederson, 2006; Perry & Hourcade, 2008), but to our knowledge none have addressed activity zones for swipe gestures.

Accordingly, our research with older adults revealed that for horizontal swipes participants performed best with horizontal swipe targets places toward the bottom half of the screen, and for vertical swipes best performance measures were found toward the right half of the screen. In addition, we found that offsets between the targets centre and participants actual touches were registered for all regions of the display. Which leads us to believe that for targets placed in more problematic regions, it might be necessary to enlarge their touchable area by the offsets found in out own research, in order to compensate for reachability issues.

Therefore …

Solution

For swipe targets requiring high levels of efficiency, place horizontal swipe targets toward the bottom half of the screen, and vertical swipe targets toward the right half of the screen. However, when screen real-estate is limited and it is necessary to place targets in regions were lower performance measures were registered, then enlarge these targets’ touchable areas by 3.27 mm to the right, and 3.1 mm to the bottom for horizontal swipe targets, and by 2.86 mm to the right, and 3.23 mm to the bottom for vertical swipe targets.

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References

Henze, N., Rukzio, E., & Boll, S. (2011). 100,000,000 taps: analysis and improvement of touch performance in the large. Proceedings of the 13th International Conference on Human Computer Interaction with Mobile Devices and Services - MobileHCI '11. New York, New York, USA: ACM Press.

Parhi, P., Karlson, A. K., & Bederson, B. B. (2006). Target size study for one-handed thumb use on small touchscreen devices. Proceedings of the 8th conference on Human-computer interaction with mobile devices and services - MobileHCI '06. New York, New York, USA: ACM Press.

Perry, K., & Hourcade, J. P. (2008). Evaluating one handed thumb tapping on mobile touchscreen devices. Proceedings of graphics interface 2008, 57-64.