CtrlMouse et TouchCtrl: duplicating mode delimiters on the mouse

Modifier keys of the keyboard such as Ctrl or Cmd are used to delimit text entry and command selection (keyboard shortcuts). \\In this paper we study the impact of the position of these modifier keys on performance and muscular load by duplicating them on the mouse. We derive two interaction techniques: CtrlMouse duplicates the Ctrl and Shift keys by associating them to the mouse buttons under the thumb; TouchCtrl automatically triggers the Ctrl key when the hand lays on the mouse. Two laboratory experiments reveal that 1) as the task requires more pointing, participants use more these techniques, 2) the temporal cost of the use of modifier keys on command selection is 0.21s, which represents 11.9% of pointing time, and 3) selection time with CtrlMouse with one or two modifiers is similar. We also deployed these techniques to ecologically validate the results we obtained in the laboratory. Finally we present several application scenarios based on CtrlMouse and TouchCtrl.