I sometimes can’t remember what I did yesterday, much less a week ago. Somebody in a crosswalk walked in front of me as I was driving- what was he wearing? What did I eat for lunch? Where did I lay my glasses? I don’t consider myself stupid, but why can’t I remember?

People are overly optimistic about the accuracy of their retrieved memories, probably because most errors have little practical consequence and go unnoticed. Given the confidence in their own memory accuracy, people have too much faith in the accuracy of eyewitnesses. Memory has a multitude of quirks and inaccuracies that creep into its everyday operation.
Quotation from Marc Green, Phd, Eyewitness Memory is Unreliable