Two-Handed Input Using a PDA And a Mouse

We performed several experiments using a Personal Digital Assistant (PDA) as an input device in the non-dominant hand along with a mouse in the dominant hand. A PDA is a small hand-held palm-size computer like a 3Com Palm Pi-lot or a Windows CE device. These are becoming widely available and are easily connected to a PC. Results of our experiments indicate that people can accurately and quickly select among a small numbers of buttons on the PDA using the left hand without looking, and that, as predicted, per-formance, does decrease as the number of buttons increases. Homing times to move both hands between the keyboard and devices are only about 10 % to 15 % slower than times to move a single hand to the mouse, suggesting that acquir-ing two devices does not cause a large penalty. In an application task, we found that scrolling web pages using buttons or a scroller on the PDA matched the speed of using a mouse with a conventional scroll bar, and beat the best two-handed times reported in an earlier experiment. These results will help make two-handed interactions with com-puters more widely available and more effective