In regards to carpet cleaning, transference refers to the movement of a liquid from one material to another. Transference occurs when one material is less wet than the other it comes in contact with. Liquid will always want to move to a dryer location and this is what happens when we blot dry carpets.
Agitation if often not required to initialize transference and most often will actually spread the spot out. This is why it is often suggested to simply blot dry a spot and not to scrub. The dryer your towel is and the longer you hold it to the carpet the more liquid that you will transfer.