(By Holger Diessel): "Demonstratives are deictic expressions such as English this and that. They indicate the relative distance of a referent in the speech situation vis-à-vis the deictic center. The deictic center, which is also called the origo, is roughly equivalent to the speaker’s location at the time of the utterance. When this and that are used contrastively, this denotes a referent in relative proximity to the deictic center and that denotes a referent at a greater distance...