In this condition two separate states of consciousness alternate with one another, during each of which there is no memory for events that occurred during the other. Each state is a complex set of memories, attitudes and behaviours with distinctive characteristics, and is sequentially and disjointedly manifested. (This is a form of hysterical amnesia). Analogous phenomena may occur with collective memory, segments of which may be activated and expressed sequentially but without reference to each other. One possible indication of this is when a body of individuals convene in one mode and subsequently reconvene in another mode wearing different hats in which it is inappropriate to make any reference to the previous occasion.