This paper describes the design and evaluation of a gesture-based scheme for issuing the back and forward commands in web browsers. In designing our gesture recogniser we conducted several experiments to determine metrics associated with the magnitude, timing and stereotypical errors of 'natural' linear flick gestures using stylus and mouse input devices. These low-level metrics are important to software designers who must implement algorithms that discriminate between gestures and other actions such as mouse clicks and drags. As well as empirically characterising gestures, the metrics provide various insights into stereotypical behaviour with gestures, including the facts that angular errors are larger in the left and right directions with the pen, that vertical gestures are 'awkward' with the mouse, and that downwards gestures are slower than other directions. An evaluation of gestures for web browsing shortcuts shows that they enhance navigation efficiency, and that participants were extremely enthusiastic about them.
