Say a capacitor is charged and then discharged through a resistor. This cycle happens over and over again many times a second.

If I place my finger on the positive end of the capacitor, the discharge time rapidly decreases.

Is this because I am preventing charge from entering the capacitor, or am I speeding up the discharge of the capacitor?

 

You might be providing an alternate path to ground via your finger.

It's hard to speculate, as you haven't given any details about the circuit.

I hope you're not experimenting with high voltage circuits.

 

To broad of a question... Can you zoom into the particular part of the electrical circuit you might have in mind.