Researchers have suggested that attention is a key moderating variable predicting performance with an input device [Greenstein and Arnaut 1988], although the attention demands of devices have not been directly investigated. We hypothesized that the attentional demands of input devices are intricately linked to whether the device matches the input requirements of the on-screen task. Further, matching task and device should be more important for attentionally reduced groups, such as older adults. Younger and older adults used either a direct (touch screen) or indirect (rotary encoder) input device to perform matched or mismatched input tasks under a spectrum of attention allocation conditions. Input devices required attention—more so for older adults, especially in a mismatch situation. In addition, task performance was influenced by the match between task demands and input device characteristics. Though both groups benefited from a match between input device and task input requirements, older adults benefited more, and this benefit increased as less attention was available. We offer an a priori method to choose an input device for a task by considering the overlap between device attributes and input requirements. This data should affect design decisions concerning input device selection across age groups and task contexts.