The surface of an touch-sensitive input device may act as a physical button that the user may push down to perform a click or other operation. For example, the user may push down the surface of the input device with one finger for a left click and push down the surface of the input device with two fingers for a right click. In one aspect, a system for detecting a left click or a right click when the user pushes down the surface of the input device is provided. When the system first detects that the surface of the input device is pushed down, the system may wait for a short period of time before making a determination of whether the user is pushing down the surface with one finger or two fingers. During this time, the system may collect additional information to make a more reliable determination.