Steven Novella makes an important point: memories are fluid. There’s no VCR in your head, and no tape recorder either, and memories are constructs. You remember the framework (sometimes very poorly) of a past event, and your brain builds a plausible set of details around it. When you picture Christmas at your grandmother’s house when you were 12, you don’t have a record in your head of how many logs were in the fireplace or a second by second recording of the flickering of the fire. You remember that Grandma had a fireplace, and sometimes she had logs burning in it, and maybe there was a fire that year, and your brain obligingly assembles an image for you.