The way the Analog Nub works is based on resistance. The circuit is always closed with a resistance between 15.0 ohms and 5.6k ohms for dead center when the resistance on pins 1&2 or 3&4 is raised or lowered would result in movement in a particular direction. This is why some people experience a runaway curser on some PSP’s if the faceplate does not have enough pressure or the contacts are dirty it will result in unbalanced resistance causing unexpected results in movement. An easy solution to this problem would to simple tighten the faceplate or clean the contacts..
An interesting fact is some touch screens work on the same principal as the Analog Nub so in theory one would be able to connect a Touch screen to analog inputs with few modifications and have it work. To further elaborate on the resistive touch panel here is the wiki definition:
A resistive touch panel is composed of several layers. The most important are two resistive layers separated by thin space. When some object touches this kind of touch panel, the layers are connected at certain point; the panel then electrically acts similar to two voltage dividers with connected outputs. When measuring press force, it is useful to add Resistor dependent on force in this model — between the dividers.
A resistive touch panel can be made with either four or five wires. The positions of the conductive contacts in resistive layers differ depending on how many wires are used. When four wires are used, the contacts are placed on the left, right, top, and bottom sides. When five wires are used, the contacts are placed in the corners and on one plate.
