Gesture Recognition on Resistive Touch Screens

...more information can be extracted from resistive touch screens by understanding and modeling the physics behind the process. When two touches occur, a segment of resistance from the passive screen, plus the resistance of the touch contacts, is paralleled with the conducting segment of the active screen, so the impedance seen by the supply is reduced and current increases..."

from: http://www.analog.com/library/analogDialogue/archives/45-06/gesture_recognition.html