1. A method for a computing system including a touch sensitive surface, the method comprising: obtaining tracking information of each contact of a set of a plurality of contacts, wherein the contacts correspond to touch objects concurrently on or near the surface, the tracking information including a position of a first contact of the set at a first time, the first contact further having a relative position to a location of each of the plurality of contacts; determining a motion of the set, wherein the motion of the set is based on the tracking information associated with each contact of the plurality of contacts of the set; determining a motion of a sub-set of the contacts of the set, wherein the motion of the sub-set is based on the tracking information associated with each of one or more, but not all, of the contacts of the set, wherein the sub-set includes the first contact, and both the motion of the set and the motion of the sub-set are determined based on the position of the first contact at the first time and independent of at least one of the relative positions; providing the motion of the set as a control signal of a first input of the computing system; and providing the motion of the sub-set as a control signal of a second input of the computing system.