The answer is persistence. It is an unsolicited recollections that people can't disremember, such as the relentless, disturbing memories of post-traumatic stress disorder. An example, said Schacter, is the event of Donnie Moore of the California Angels, who tossed the pitch that lost his team the 1986 American League Championship versus the Boston Red Sox. Moore engrossed on the bad play, said Schacter, "became a tragic prisoner of memory," and in the end committed suicide.