The movie Memento provides excellent illustrations of several important scientific characteristics of memory. In this post lets examine the assertion, made by the main character Leonard, that memory cannot be trusted. When I teach classes in Introductory Psychology, the section where the topic of memory is discussed is always one of the most fun. At the start of class I have the students do an in-class exercise. I ask them to think (to themselves) about their most precious early childhood memories and then pick the one that is most vivid and about which they could, if asked to do so, write the most detailed description. After the students have thought about this for a minute or two, I announce to the class that the memories they are each thinking about never actually happened. As you might expect, this assertion generates a lively discussion and meets with a high level of resistance! However, I always win this argument in the end because the scientific studies demonstrate overwhelmingly that this is true.
Contrary to popular belief, our memories do not provide us with the kinds of information that would have been recorded if a video camera had been attached to our foreheads throughout our lives. If we want to think of memories in terms of an analogy to a video tape, we will need to imagine that the tape has some of the following characteristics. Something on the order of 99.9% of the original video has now faded to the point that if you play it back you discover most of it is blank. Occasionally you come across a short snippet of an image, but most of those images are so blurry and fuzzy that it is pretty hard to make out what is going on. VERY occasionally you come across a snippet that is vivid, in high contrast, and you can see lots of details about what is going on. But when those vivid sections of the tape are examined with special technical equipment we discover something really peculiar. None of those vivid images are original recordings. The original recordings have been written over numerous times and all of the vivid details were added during the re-recordings. What is worse, many of the details in these re-recorded images are completely different from what was present on the original recording. To add insult to injury, as you watch this tape, you, the viewer of the tape, have absolutely no way to differentiate which of the images on the tape are original recordings (true memories), and which are added images of events that never originally happened (false memories). So what would you have to do if you were asked some question about your past, and your only source of information was what was recorded on the tape? All you could do is play back the tape and try to reconstruct what happened based on the sparse snippets of images (true and false) that are present on the tape. Psychologically, you might have confidence in your reconstruction, but from a scientific perspective you would have to admit that the reconstruction could not really be trusted.
Similar to the tape in this example, real memories have the perverse characteristic that the ones that are the most vivid and have the most details are precisely the ones that are most likely to be false! This is because the memories that are most meaningful to us are the ones we think about the most. And each time we think about a memory a few new details can be added in and a few others dropped. Our memory systems operate like the fisherman who retells his tale over and over with the fish getting larger with each retelling. Or like children playing the game of telephone tag, with details being added and dropped at each stage of the retelling until at the end the story has little resemblance to the original.
In addition to creating false memories by modifying true memories over time, sometimes false memories are created from the beginning. These are referred to as implanted false memories. A large number of scientific studies have been performed demonstrating the ease with which false memories can be implanted. An example would be a study in which a group of subjects is brought to the laboratory under the pretext that the purpose of the study has to do with some topic such as dealing with fearful experiences. What the subjects in the experiment do not know is that one of subjects in the group is a confederate, a person working with the experimenter. During the course of the experiment, the confederate relates an experience he had as a child during which he became separated from his mother while at a circus and was frightened by a clown. Six months to a year later, the same subjects are brought back in, one at a time, for a follow up to the study. The experimenter asks each subject a series of questions about memories of frightening experiences. One of the questions is whether the subjects recall ever having any scary experiences that involve a circus. A startling number of subjects report recalling, AS THEIR OWN EXPERIENCE, the implanted false memory of being frightened by a clown while separated from their mother at a circus.
Implanted memories do not have to be false. Many implanted memories in real life do in fact correspond to events that actually happened. For example, we might have a vivid memory of a childhood birthday party, and think we are remembering the actual event. However, it has been demonstrated in scientific studies that many of the details we remember about the party, even though they actually happened, were implanted later in life as we viewed photographs of the event, heard our parents and other relatives tell stories about the event, etc.
Implanted false memories that can not be trusted are a source of real concern for law enforcement. We now know that it is critically important for police officers and other professionals who interview witnesses or victims of crimes (including cases such as reported child abuse) to do the interviews in the right way. If not, the interview itself serves the purpose of implanting a false memory. And once a memory has been implanted, the person recalling it can not differentiate whether it is a true memory or a false memory.
The structure of the film Memento is quite ingenious in the way it creates false memories in the viewer (us) as we watch it. More on that in a later posting.
My next posting in this series about Memento is Part 5.