These are errors and illusions in memory and their reproduction. They may consist of: treatment of fantasies as genuine events; belief that events similar to a unique event have previously occurred (reduplication of memory); or belief that an event identical to a previous event has previously occurred (déjà vu). Whilst all remembering depends heavily on reconstruction rather than on mere reproduction alone, confabulation is a highly error prone form of production of spurious memories and fabrications. Analogous phenomena may be found with collective memory particularly in some of the abuses of speech-makers and the media whereby facts are invented which appear to fit the context of a presentation. These processes also be associated with the important phenomena of rumour in establishing public opinion.