How sensitive are the driver station digital inputs?

[FRC4ME]

Okay, so we've plugged four switches into four of the eight digital inputs on the driver station and written code to make those inputs do something when turned on. Yes, we remembered that on is false and off is true in the code. The switches all seem to work fine.

One day, however, we made a very interesting discovery; whenver someone touches the PWM cables, whatever input is connected to that cable begins pulsing on and off. We discovered this when someone was bundling up the wires and everything on the robot started moving. It was quite fun to impress the build team with our magical powers.

Right now, we've solved the problem by wrapping the wires in spiral plastic, but does anyone have an explanation for this? Are you telling me those digital inputs are so sensitive, lightly touching an insulated area of the PWM cable is enough to set them off? Are we the only ones with this problem?

When wiring the switches, we connected ground (black) to one terminal and signal (white) to another. Is this correct?