We investigated how different categories of input devices, direct and indirect, affected performance under different attentional conditions. We also examined the moderating effects of age on input device usability. Previous studies have found differences in performance between the two types of devices as well as interactive effects of age (e.g., Charness, 2001). Previously, researchers have suggested that attention is a key moderating variable predicting performance with an input device; however, no age-related studies have systematically manipulated attention when examining input devices. In the current study, younger and older adults used an input device, direct (touchscreen) or indirect (rotary encoder), to perform tasks under various attention allocation conditions. The tasks were comprised of on-screen controls which were then analyzed by the type of input device used. Age and attention allocation together were needed to predict usability of an input device. We discuss how these data can be used when making input and interface design decisions across user groups of different ages.
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