You have employed RECOMMENDED SWIPE TARGET SIZES throughout most of the swipe targets that make up your UI. However, in some cases you have found that this range of sizes does not provide a satisfactory solution.
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Using RECOMMENDED SWIPE TARGET SIZES throughout your entire user interface is the ideal solution. However, in cases where screen real estate is limited, this might not be possible.
The amount of available screen space is mainly influenced by the number of targets that need to be displayed, as well as by all of the remaining content that makes up your interface. Throughout the screen flow of a particular application, there might be cases where large target sizes are not an issue, but other situations where large amounts of content are needed, or a numerous group of swipe targets requires displaying. Consequently, there might not be enough space to accommodate all elements while still using RECOMMENDED SWIPE TARGET SIZES.
Hence, depending on the amount of content, as well as on the number of swipe targets that make up a particular screen, it might be necessary to reduce swipe target sizes.
In that case, it is important to know within what specific range of smaller swipe target sizes older adults’ accuracy rates and task completion times, maintain themselves within acceptable levels. Although these values will be inevitably lower than with RECOMMENDED SWIPE TARGET SIZES, they might still be within satisfactory standards depending on the performance requirements of the task they are assigned to. A UI designer should always be aware that reducing target sizes could make a product more difficult to use. This additional difficulty might provoke frustration and anxiety among older adults. This particular audience is generally more susceptible than their younger counterparts toward negative feelings while interacting with technology (Czaja & Sharit, 1998; Laguna & Babcock, 1997; Turner, Turner, & Van De Walle, 2007).
Our own work suggests that older adults are able to use a certain range of smaller swipe target sizes while still maintaining performance measures at satisfactory levels. This range of smaller target sizes includes those between 10.5 and 14 mm, where mean accuracy for the 10.5 mm targets was 95.24%, and mean task completion times were 2.68 seconds. For targets smaller than this, mean accuracy decreased to 91.90%, and task completion times increased to 2.75 seconds for the 10.5 mm targets, and for the 7 mm targets mean accuracy lowered to 86.25%, and task completion times increased to 3.5 seconds.
When the necessary screen real estate to implement RECOMMENDED TARGETS SIZES FOR SWIPE GESTURES is not available, and the task does not require high performance levels, then use target sizes for swipe gestures that are at least 14 mm square.
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Czaja, S. J., & Sharit, J. (1998).Age Differences in Attitudes Toward Computers. The Journals of Gerontology Series B: Psychological Sciences and Social Sciences, 53B, P329-P340. doi: 10.1093/geronb/53B.5.P329
Laguna, K., & Babcock, R. L. (1997).Computer anxiety in young and older adults: Implications for human-computer interactions in older populations. Computers in Human Behavior, 13, 317-326. doi: 10.1016/S0747-5632(97)00012-5
Turner, P., Turner, S., & Van De Walle, G. (2007). How older people account for their experiences with interactive technology. Behaviour & Information Technology, 26, 287-296. doi: 10.1080/01449290601173499