they would be if we had the physical photo in our hands and were looking at it. The only problem is that these tracks of imagined memory activity are enlarged retrospectively until they artificially grow to be as big in our memory as real-life stories.
This phenomenon has been studied by showing test participants a series of different photographs from daily life situations.10 On the following day, the participants were reminded about the photos from the previous day by being told brief descriptions. What they didn’t realize, however, was that some of the descriptions were deceptive and falsely described the photos. Misled in this way, some of the participants formed false memories of the original photos and were no longer able to select the correct (original) images from a selection of photos. Some of the participants even claimed to have seen a manipulated version of an earlier photo. At this point, the level of brain activity triggered was very similar for true and false memories, with one decisive difference: the image processing area became more active with the correct memories (since the participants had, after all, really seen these photos). On the other hand, if a participant incorrectly recalled an image, the audio area of the brain was more active (because they mixed up the new deceptive information that they had been given verbally with their actual memory). In other words, if the total amount of activity covers enough area and is integrated into the brain, the memory is accepted as true, even if it is not.
This study significantly illustrates that memories are by no means static but, on the contrary, may be altered retroactively—and that this takes place every single time you bring them out and dust them off. Whenever a memory is in this state (of being hauled out and dusted off), it is particularly vulnerable to external influences. One elegant experiment was able to demonstrate this effect. Participants were first asked to memorize a list of words and then received a new list the next day. Before being given the new list on the second day, half of the participants were asked to try to remember the first list. On the third day, all of the participants were tested on their memories. Some participants who were once again asked to try to remember the very first list got it mixed up with the second list—but only if they had also been asked to remember the first list on the second day. Those who only concentrated on the second list on the second day (and were not asked about the first list) were able to separately recall both the first and second lists.11 The conclusion: a memory that is in the process of being recalled is in a fragile state and susceptible to corruption by new information.
Peer pressure memory falsification
AS IF IT wasn’t enough that we can make mistakes when saving information, as well as altering our memories each time we pull them out, we are also hardly able to defend our memories from being actively manipulated by external factors. Even if we are aware of this, we are powerless and continue to indulge in memory falsification. Peer pressure—the obligation to adapt our memories to those of other people—actively influences our memories.
In order to demonstrate this concretely, participants were shown a two minute documentary film and then asked a series of questions about the video.12 Directly after viewing the videos, participants made few errors in their responses and were correctly able to recall the details. Four days later, they could still remember the details and didn’t allow their memories to be swayed by any false information about the film. This changed, however, when participants were shown fake responses about the film made by other participants. Upon seeing the incorrect answers of others, participants were also drawn toward the wrong answers themselves. Even after they found out that the other answers had been contrived and didn’t have anything to do with the documentary, it was too late. The participants were no longer able to distinguish between truth and fiction. They had already modified their memories to fit the group. Interestingly, this peer pressure effect is conveyed through a brain region that neighbors the hippocampus, called the amygdala. This almond-shaped, dice-sized region showed a flurry of activity, particularly whenever the fake responses were shown along with a photograph of the other participants and not merely in writing. A human face increases the feeling of peer pressure and leads our memory further astray toward false conclusions.
It is now possible to list all the ingredients needed to concoct a false memory: an emotional event, a dash of peer pressure, and a habit of frequently recalling a memory, which gives it the opportunity to become further distorted. When this happens, it is nearly impossible to distinguish false memories from true ones. If you would like to cause someone to generate a false memory, it would be best to do it in steps. First, confront the person in question with a distinct (but falsified) memory scenario—for example, that he or she once lost their parents in a store as a small child or that they got into trouble with the police as a teenager. Reinforce this with the fake claim that relatives would be able to back up this situation. Ask your test subject to imagine the event in question and then to think about it for a few days. Then grill them once more with questions, appeal again to their imagination, pressing them for details. Usually by the second sitting, detailed but false memories start to emerge. In this way, it’s not only possible to get a twelve-year-old to contrive absurd stories (for example, that he or she was abducted by a UFO13), it’s also possible to convince 70 percent of adult participants that they had once committed a crime, even if such a claim was completely fabricated.14
The start of this chapter showed what can happen if one spends weeks, or even months, performing such imagination exercises for false memories, and this very important point cannot be emphasized enough: don’t depend on your memory! It is never one hundred percent correct, and it has more likely than not been embellished, distorted, or partially erased by your own brain. You have been influenced by other people, and you are subsequently unable to tell a false memory from a true one. Even the brain is no longer anatomically able to distinguish one from the other since the activity patterns of true and false memories are nearly identical. There are, however, two small but fine exceptions. First: correct memories trigger more activity in the hippocampus and in the image processing regions (since one experienced the true memories, after all). And second: fake memories result in increased activity in the frontal cortex (presumably because the brain must exert itself somewhat in order to come up with an artificial memory image).15 However, the neural network is so similarly and expansively activated for both types of memories that it becomes impossible for you to be able to tell the difference anymore. As I mentioned earlier, at this point it no longer even matters whether you know that you have been falsely informed. Once an incorrect memory has fallen down into the well and been absorbed, it becomes as authentic as a true memory. Reality and truth are thus two wholly different things.
Memory rescue
BY NOW YOU are probably wondering what you can possibly do to save your true memory from being taken in by a fake one. In principle, there’s not much you can do because this memory system is quite robust and is going to go on leading you around by the nose. However, neuroscience has a few findings that show it’s possible, under certain conditions, for our memories to become even more robust.
Possibility 1: You grow older. Specifically, memory improves and people are less prone to develop false memories when, for example, they are warned about the pitfalls of false memories before taking a DRM test. If I were to have you repeat the same test that you took at the start of this chapter, you should have learned by now that you are sometimes going to fall into a habit of mental pigeonholing that you formed while you were saving information. Interestingly, this tendency to be cautious becomes more pronounced the older one gets. This is why it is possible for a sixty-six-year-old person to effectively shield themselves from new false memories if they have been duly warned on that topic before taking a memorization test. Younger people (ranging from eighteen to twenty-three years old) who receive the same warning still fall prey to false memories.16 Their brains are apparently more eager to go about constructing mental boxes, which serve to obscure the facts. Older brains, by contrast, feature more control mechanisms (or, to state it in a negative sense: they are already stuck in their own ways and are therefore less vulnerable).
Possibility 2: You take birth control pills. Women who use hormonal contraception perform just as poorly on the DRM test as women who are not on birth control. But they are less susceptible to any later misinformation. If you show them photographs from daily life scenarios and then later mention that the scenes appeared