Memory load differentially influences younger and older users' learning curve of touchscreen gestures.

In this study, we employed a recall test to investigate how memory load affects the learning curve of gesture-letter pairs for younger and older users. The gesture-letter pairs were carefully designed to mimic real-world gesture-function/command associations on a touchscreen mobile phone. Both younger and older user groups showed lower recall accuracy as the memory load of gesture-letter pairs increased, and recall performance improved with repeated memory training. More specifically, younger users improved rapidly over repeated memory sessions under all memory loads, whereas older users benefited much less from repeated memory sessions except the lowest memory load of 6 gesture-letter pairs. These results reveal that the memory load differentially modulated younger and older users' learning curves of gesture-letter pairs. Thus, our work suggests an upper limit when adding new gesture-function associations on mobile phones and special attention should be devoted to old users.