When humans learn anything, it is stored in their actual dissociation. Dissociations change, sometimes they last no longer than some seconds. A lot of repitition is nessecary to make these new memories available for many other dissociations, that process is called slow thinking. All memories inside the same dissociation are immediately available - fast thinking. The more permeable a dissociation is to others, the more associations it returns during thinking. The size of their short term memory defines the limit, how much of these associations humans can process and when a dissociation becomes unstable. Derealization is a possibility to stabilyze a dissociation (that cheese dome around us during tests in school). Depersonalization is the opposite, a kind of exhaustion, when it is no longer possible to keep up the actual dissociation and dissociations change every 5-30 seconds.