Matti Ryynänen

Making an impression: force-controlled pen input for handheld devices

The properties of force-based input on a handheld device were examined. Twenty-one participants used force input to set 10 different target levels representing consecutive force ranges (0 to 4N) with visual feedback (digits or bar graphs) or no feedback. Both accuracy and speed were greater with analog feedback (bar graph). Statistical comparisons of adjacent targets/digits indicated that subjects differentiated roughly seven input levels within the set of ten force ranges actually used. Time taken to input the target force increased significantly with the size of the target force, suggesting that smaller force ranges should be considered in future implementations of force input. The results are discussed in terms of the design of appropriate feedback for force input.