The reason false memories are easily implanted into our heads and tricks us begins to make more and more sense when you understand how we revive old memories. Jessica Snyder Sachs wrote an article for Popular Science about how our memories are like video tapes that are scattered around our head. As we look for a single video tape of a memory, we often cannot find it, but we have found pieces of the event. We cannot grasp every detail but we can try to guess what is missing. We take bit and pieces and try to weave them back into what we think happened, filling in blank spots with logical guesses. When more and more details are missing, the brain has to make even more guesses and As more details are missing from the memory, the more freedom the brain has to fill in what happened. This can stretch the truth further and further until the memory is barely a shell of its original self.
Now thinking about how the mind instinctively fills in blanks, we can see why we can be fooled by false memories. We do not want to think we forgot something so we use the tiny bit of information we have and fill in any detail we can imagine to form a logical recreation of what we think we have forgotten. Eventually the information begins to make sense with the details we fill in, we can easily believe that it did, in fact, happen.
A Spielberg in your own mind
By Jessica Snyder Sachs; Popular Science; July 25, 2003