memento depicts the story of a man who has excellent memory
pearce stars as a man who  as a result of a past trauma  suffers from anterograde amnesia  the inability to form new memories and suffers shortterm memory loss approximately every five minutes
anterograde amnesia is a loss of the ability to create new memories after the event that caused the amnesia  leading to a partial or complete inability to recall the recent past  while longterm memories from before the event remain intact