An error in the function of the memory, in which the evocation of certain memory data is blocked. That is, there is no register of the sensations that correspond to the given range of memory data because they have been influenced by other types of sensations. A prime example is painful sensations which are rejected by the structure and drag with them into forgetfulness all the other data that accompanied them (See, Forgetfulness). Sometimes data that cannot be deliberately evoked will be expressed in the lower, non‑vigilic levels of consciousness. If the mechanism of pain is operating while data are being recorded, sooner or later this may make the information vanish; experiences recorded with pain are either forgotten completely or evoked by the consciousness with a considerable transformation of any associated contents. There are many types of amnesia, among which are: retrograde, postgrade, and retro‑postgrade, all of which may occur with respect to a given fact.