Déjà vu, the sense of “I know I’ve experienced this before…” is still a mystery to scientists. There are multiple theories about what is actually happening in our memory banks for us to feel familiarity in a new or novel situation, but none has gained a consensus. It occurs when we encounter an event or image that feels very familiar, like it’s not the first time we’ve been there—yet we are unable to recall from where, and it may indeed be the first encounter. It seems like our memories are fabricating experiences for us or, alternatively, creating false feelings of familiarity for an unknown reason.
This eerie intuition happens to between 60% and 70% of us, most of whom are between the ages of and years old. Due to it being a miswiring of the brain, you might suppose that it occurs more to the elderly—it doesn’t, so that almost adds to the mystery. Is it something that only happens when the brain is developing and pruning down its mistakes? More mystery abounds.
Déjà vu is the French expression meaning “already seen.” Because déjà vu happens so randomly and in people without a clear medical condition to explain it away, it is a difficult phenomenon to study. Even the why and how of the phenomenon is up for debate. Psychoanalysts—in the vein of Sigmund Freud and unfulfilled unconscious drivers—tend to believe it is wishful thinking and an overly active subconscious, while psychiatrists—in the vein of exorcising past traumas—often attribute the experience to the brain mistaking the present for the past.
Perhaps the simplest and most plausible explanation is that déjà vu is a result of wayward memories that were once learned but forgotten, leading to feelings of familiarity despite no real recollection. Imagine receiving a light burn scar on your hand that fades over time to the point where you forget it happened, though there remains a small discolored mark. While a leading idea, it doesn’t quite explain the results that many scientists have produced in their research on déjà 104 vu. All of the evidence points to déjà vu being more of a biological phenomenon in our hippocampus, the brain structure where the memory resides.
One leading theory is that déjà vu is an error in the way we process memories. When we process information from our daily lives, our brains go through a specific sequence. (1) First, our brains search through our memories to see if we can gain understanding through comparison to a past experience, and if it comes up with a match, (2) a separate area of the brain identifies the new situation as familiar, and context is instantly gained. This helps with quick processing and analysis of novel situations. For instance, we may never have driven a motorcycle before, but our brains can compare it ever so slightly to aspects of riding a bicycle.
During an episode of déjà vu, the second part of the process seems to be triggered by accident. This is when you see something that isn’t related to a bicycle, but that feeling arises anyway. 105
For a more illustrative example from the other side, if you find yourself in line at a café and standing behind a clown making balloons while balancing on a unicycle (something you are sure to be unfamiliar with), a déjà vu moment would result in you identifying this situation as familiar and not novel. This occurs unconsciously, but consciously, you will be hit with opposing feelings of familiarity and novelty. That ensuing confusion is what we are most familiar with.
For a third theory, déjà vu is theorized to be a miscommunication between sensory input and our memories recalled. Some researchers speculate that the brain, in an attempt to make sense of the world with the limited amount of information we are actually able to process, fills in the gaps of the information that is missing. For our brains, it only takes a small amount of sensory information to have us recall detailed information. Taking our clown café example from earlier, this theory would suggest that our brains create a 106 feeling of déjà vu because there are individual elements that are similar to what we have experienced in the past. Overall, déjà vu helps provide a more complete picture of what is happening, though it may not be accurate or warranted.
A similar idea states that déjà vu is simply a timing error—as we take in a moment with our senses, the data is being stored in long-term and short-term storage at the same time. Two processes occurring at the same time clutter up our mental bandwidth and causes a delay between the moment and storing it, which we may experience as that unsettling feeling of déjà vu.
Finally, déjà vu might be a sign of the brain checking its memory for integrity and slip-ups. This theory comes from researcher Akira O’Connor and was created after he noticed brain areas involving decision- making (the prefrontal cortex) as opposed to memory (the hippocampus) become active during induced déjà vu. To O’Connor, this implied that the brain is actively thinking through memories and then sending signals if there is a mismatch between the memory and what actually happened.
Of the multiple potential causes for déjà vu, Dr. Elizabeth Reichelt of the University of New South Wales has said the following:
So far there is no simple explanation as to why Déjà Vu occurs. It is thought that Déjà Vu could be evoked by a mismatch between the sensory input and memory-recalling output. This theory indicates that the mismatch between knowing an event is new, but it feeling familiar is because of sensory environmental information going straight into long term memory… The familiarity we 108 experience in a Déjà Vu event exposes that there are different memory systems located in the hippocampus. Instead of sensory environmental information passing from short-term stores into long-term memory, in Déjà Vu, information bypasses short-term memory and instead reaches long-term memory stores directly. This explains why a new experience can feel familiar, but not as tangible as a fully recalled memory. As to why our brains have this processing quirk, it has been asserted that human memory developed this ability to help survival. The ability to recognize new situations and predict the future based on past experiences may have helped us avoid certain dangers. It’s safer and more 109 thorough than depending merely on your actual memories, which are necessarily limited. For instance, if you were walking into a dark alley and you had a sudden déjà vu feeling of past bad experience, you might be safer.
One thing is certain—it’s an odd feeling that makes us doubt our reality. One peculiar aspect of this is the notion that déjà vu makes us feel like we can predict the future. Suppose you’re doing something that feels so familiar that you know what will happen next. That’s just a natural direction for your thoughts to go. This is known as precognition. Are precognition and déjà vu two sides of the same coin? Or is it more likely that experiencing one simply makes experiencing the other more likely?
Anne Cleary, a cognitive psychologist at Colorado State University, has dispelled this misplaced belief and shown that the feeling of knowing that déjà vu can sometimes impart is only a feeling. She did so by having participants watch video 110 scenes in which they went through a series of turns. Déjà vu was then induced, and they were asked what the final turn in the video would be. They mostly guessed wrong, although they felt confident that they could predict the future.
In the end, déjà vu ends up being one of the more mysterious quirks of memory because of how the scientific community still collectively shrugs at the cause. However, it may pale in comparison to the next memory malfunction: false and implanted memories.
False Memories: “I Swear It Wasn’t Me.”
Perhaps what we actually remember is a set of memory fragments stitched onto a fabric of our own devising. If we sew cleverly enough, we have made ourselves a memorable story easy to recall. – Carl Sagan
False memories are on the extreme end of the spectrum, where it’s not a matter of remembering incorrectly or forgetting a few details—it’s about starting with a narrative or emotion and making your memories fit instead of the other way around through observing the world and recording what you see. This is where we start with a conclusion in mind and bend our memories to fit it. We mentioned earlier that our memory’s purpose is not exactly to record reality; it’s to reinforce whatever conclusion or feelings we wanted reinforced. It’s there for our benefit, not our analysis. A 2014 study published in the Journal of Neuroscience studied how our brains rewrite our memories to be more useful and helpful. In the study, people looked at objects with backgrounds on a computer screen. Then they had to place the object in the original location but on a new background. The participants always put the object in the wrong spot. Finally, they were shown the object in three locations— where it was originally, where it had been placed the second time, and a brand-new location—and asked to pick the correct spot for it. The researchers found that people always chose the second location rather than the first. Their memories were literally updated with more accurate information; this can be seen as a survival mechanism for better decision-making. It’s also a scary peek into how susceptible our memories are to after-the-fact editing to fit a narrative or purpose. Just because our memories are capable of remarkable feats doesn’t mean that they aren’t subject to errors that are just as remarkable. False memories are a topic that has been heavily explored in neuroscience, with no real conclusion other than “they happen because our memories are gullible.”
A false memory is a memory that is neurologically identical to a real memory but based on something that did not actually happen.
In 1995, Elizabeth Loftus and Jim Coan from the University of California, Irvine, conducted a study to investigate how to implant a false memory by fusing it with an existing, real memory. The study involved a subject who was given descriptions of three true memories from his childhood and one false memory. The subject wrote about each of the four memories for five days in a row, giving a summary and any details or facts he could remember about each of the memories (again, three real and one false).
Over the five days, the subject began to recall more and more about the false memory, introducing details that were never there and that seemed to stem completely from the subject’s imagination. He purported to remember everyone that was present and even the emotions involved. He was adding onto the false memory, not realizing that he was treating it as a real memory, and quickly blurring the lines even though he was aware it was made up. At the end, the descriptions were all equally detailed and legitimate-sounding.
Weeks later, the subject was asked to rate his memories for how clear they were. He gave the false memory the second highest rating out of the four memories presented. He could provide vivid detail—perhaps because it was fabricated, so the details conformed to his idea of what the 114 experience would usually entail. And just like that, he wasn’t sure which parts had really transpired or not. He may have known that the memory as a whole was false, but he couldn’t determine how much of it was made up anymore. Memories could be implanted in people just by saying that they had occurred a few times.
Are we really so accepting? Well, yes. Memories, if they are not entirely false or fabricated, can also be influenced by things as small as suggestive word choice, phrasing, and vocabulary. Another study conducted in 1974 by Loftus at the University of California, Irvine, illustrates this effect.
Subjects watched different videos of car accidents at three different speeds. After, they filled out a survey that asked, “About how fast were the cars going when they smashed into each other?”
Other groups of subjects watched the exact same videos and filled out a survey after as well, but the survey instead asked, “About 115 how fast were the cars going when they bumped/hit/contacted each other?” The estimates the subjects gave changed in relation to the verb used, which influenced the perception of speed and impact.
• Smashed = 40.8 mph • Bumped = 38.1 mph • Hit = mph • Contacted = 31.8 mph
This simple change in vocabulary affected people’s perception of an event and, in essence, changed their memory surrounding it. How reliable can memory truly be when we are manipulated by such small variables? This was an event that the subjects watched on video—and the speed increased by nearly mph when leading language was used—a discrepancy of 25%.
There are no real biological explanations for these things, as the three-step process to creating a memory is the same with fake or real information—the brain processes it all the same. So what tendency underlies our gullibility? It’s more of a psychological 116 tendency; perhaps it is our drive to protect our egos and shield ourselves from judgment or being wrong.
Sometimes, despite our best efforts, however, we are indeed wrong! This is courtesy of what’s known as the Mandela effect, named for the phenomena of countless people falsely remembering that Nelson Mandela died in prison in the 1980s, when in fact he only died a few years ago in 2013. At first, this was “explained” as a manifestation of movement between parallel universes, each with their own different set of world history events. That explanation, however, is somewhat less likely than simple confusion and fabrication of memories through social reinforcement. In other words, if one person says something, you might believe it, but this belief grows stronger the more you hear it. The ease with which false memories are created is why eyewitness testimony occupies such an ambivalent place in the legal system. Memories can change each time a witness is interviewed, and 117 sometimes they can be intentionally manipulated by one or both parties. For example, Annalies Vredeveldt of the University of Amsterdam states that asking questions about a memory can easily take a wrong turn if you ask questions as simple as, “What was the color of his hair?” or “He was a redhead, wasn’t he?” The first question assumes that there was a male, and the second question assumes that there was a redheaded male. Both questions are leading and draw their own conclusions. As we saw earlier with the choice of vocabulary changing people’s estimations of speed, a direct implication can have even more powerful effects on a memory.
Eyewitness accounts are highly trusted by juries yet highly condemned by judges and attorneys who know better. Researcher Julia Shaw states that to implant a false memory, “you try to get someone to confuse their imagination with their memory and get them to repeatedly picture it happening.” This means simply repeating a false memory or story to someone can cause them to confuse the false memory with reality and eventually mesh them together with the real account. There is a very thin and blurry line between memory and imagination, and we saw it in action with one of Loftus’s earlier studies. Eyewitness testimony has been questioned since Hugo Munsterberg’s seminal 1908 book On the Witness Stand. He questioned the reliability of memory and perception, and the legal community has taken notice ever since. What’s scary is that research has shown that juries can’t tell the difference between false and accurate witness testimony and often simply rely on how confident the eyewitness is (Nicholson, 2014).
As we will soon learn with flashbulb memories, confidence is never the hallmark of accuracy. Additional support for the distrust in eyewitness testimony has been found in analyses by Scheck and Neufel, who proved that eyewitness testimony was frequently present in cases of suspects who were later exonerated based on DNA evidence.
With the knowledge of how unreliable memory can be and just how easy it is to implant false or biased memories, it’s a wonder eyewitness testimony is still allowed at all. Christopher French of the University of London sums it up best:
Our memories are incredible, but the same malleability that leads to memory feats can also be exploited to show great flaws. These create flawed thinking, not out of unsound logic or perception, but if you literally remember something to be different from reality, you’re going to have some kind of trouble. The main goal of our brains isn’t to be accurate or even helpful, and thus, it can be easily manipulated and tricked.
Flashbulb Memories: “Do You Remember Where You Were During 9/11?”
One curious and constant aspect of memories is just how confident we are in them, despite how malleable they are. We’ve explored this in previous sections, but this disparity of confidence and accuracy is the most glaring when we talk about flashbulb memories.
A flashbulb memory is a memory that feels like you can reach out and touch it. It is incredibly vivid, clear, and detailed. It creates an almost supernatural sense of knowledge where you feel that everything is burned into your brain for the rest of your life. For example, depending on your age, do you remember where you were and what you were doing the moment you heard or read about the tragedy of 9/11 or the assassination of President John F. Kennedy? It can also be a personal event, such as finding out that you are pregnant. Though the term was coined later, this phenomenon has existed since large events like the assassination of President Abraham Lincoln and the bombing of Pearl Harbor.
I remember watching the attack on the World Trade Center on television at school and hearing the school announcements while in a daze in my biology class. The voice on the intercom was close to tears, and the rest of the people in the classroom were sitting in stunned silence. The professor wasn’t present at the time, but I remember that the person sitting next to me gasped and grabbed her blue sweater tightly. I was wearing black Nike sneakers, and halfway through, the professor walked into the classroom. At least, that’s what I think I recall.
Flashbulb memories are built around significant and life-changing events, whether personal or historical. As such, there was a large emotional impact on you, and this intense flash of emotion makes you feel like you remember everything about that exact moment. This just might be the origin of why near-death experiences are like seeing your life flash before your eyes. In either case, you are put into a reaction of awe and shock. Biologically, this means your senses are alert and adrenaline is coursing through your body. You might be shaking afterward because of the excess adrenaline.
Your heart might be beating fast, and your palms might be sweaty. Because of the emotional impact, flashbulb memories have been seen to involve the amygdala, one of the brain’s main processing centers for emotion.
All of this adds up to a belief that you know exactly what is happening at that moment. This might be true, but whether you remember it accurately or not is a different matter.
The term “flashbulb memories” was coined in 1977 by Roger Brown and James Kulik, who proposed that they existed and were forever etched into our brains as an evolutionary defense mechanism. Suppose you were attacked by a wild animal, something that would cause a flashbulb memory because it is so emotionally traumatic and impactful. Brown and Kulik hypothesized that the use of flashbulb memories was so we can go back in time, to the moment of danger, and analyze in great detail how we can avoid similar situations in the future.
Strong emotional impact is the genesis of a flashbulb memory. Therefore, whether flashbulb memories are formed is largely subjective. Flashbulb memories are intense, but they have been shown to be less than reliable. As you’ve read in this book, our memories are highly susceptible to manipulation, whether they get mixed up with fantasy or daydream, they degrade naturally, are skewed by our natural biases, or are influenced by other factors.
For example, if you develop a flashbulb memory around 9/11, your account could shift according to the following:
• How you daydreamed about making an impromptu patriotic speech in front of your family.
• What your friends told you about 9/11 and their flashbulb memories surrounding it.
• How you feel about 9/11 and your reaction.
Let’s also address what happens to us when we are in a physiological state of high arousal. Imagine when you are angry or emotional. Is this typically when we see things objectively or accurately? Is this when reality is the clearest to us and when we can think with the most clarity? In fact, it’s the opposite. The very conditions that make us susceptible to creating flashbulb memories are the ones that make them inaccurate.
We emphasize this because much of the research surrounding flashbulb memories is about their accuracy. People’s confidence in them has historically been high. On September 12, 2001, David Rubin and Jennifer Talarico, researchers from 125 Lafayette College, asked a group of students about their memories regarding the attacks the day prior. They also asked them questions about the week prior to the attacks. This allowed them to directly compare a flashbulb memory and a normal memory of life and see how their accuracy kept up over time. Of course, the memories about 9/11 were far more vivid and confident.
After one week, both memories had about the same rate of accuracy and consistency. But at separate points of one month, and seven months after September 12, the rate of inaccuracy and forgetting was also the same between the two memories. In addition, there was the same rate of errors introduced. In the end, flashbulb and normal memories ended up having the same accuracy. There was nothing special about them in the one way that memories are measured in: accuracy.
It’s a scary thought to believe in something so much and yet still have it be proven incorrect. The only thing that truly separates flashbulb memories from normal memories is our perception of them.
Overall, they continue to emphasize how suggestible our brains are. Memories are unremarkable and common—what’s to stop them from being easily confused, mixed up, or entirely planted and fabricated? Unfortunately, nothing. Recall that our realities are the sum of our memories—so what does that mean if we want to understand the simple difference between objective accuracy and subjective perspective? I’ll be waiting for the answer.
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- Brain Blunders: Uncover Everyday Illusions and Fallacies, Defeat Your Flawed Thinking Habits, And Think Smarter (Or Just Less Stupidly) By Peter Hollins
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