Deja Vu
Deja Vu - The Fascinating Science of Déjà Vu
Unlocking the mystery of familiarity.
Updated December 20, 2023 | Reviewed by Gary Drevitch, Co-authored by Meghan Mcgrogan
Déjà vu is the conflict between false familiarity and rational knowledge, not just a feeling of familiarity.
Déjà vu is a sign of well-functioning fact-checking mechanisms in the brain, not a memory error.
Fatigue, stress, and dopamine can increase déjà vu likelihood. Exhausted brains are more prone.
Persistent déjà vu (déjà vécu) may be distressing, linked to conditions like dementia.
Have you ever experienced that uncanny feeling of déjà vu? You know, that strange sensation of having already experienced something happening in the present moment? Déjà vu has long fascinated scientists. Below, we dive into the world of déjà vu research, exploring the latest insights from neuroscience and specifically the work of Akira O'Connor, a neuroresearcher at the University of St Andrews.
More Than a Simple Memory Fault
An oddity of human memory, déjà vu is more than just a fleeting feeling of familiarity. According to O'Connor, it involves a unique awareness that this familiarity is misplaced: "Déjà vu is a conflict between the sensation of familiarity and the awareness that the familiarity is incorrect. And the awareness that you're being tricked makes déjà vu so unique compared to other memorable events." This understanding highlights the phenomenon's complexity and sets it apart from ordinary memory recall.
What’s Happening in the Brain
Déjà vu shares some of the same attributes as delusion. Within a delusion, there is a belief that is not supported by facts, and it continues to be a product of thought for an individual, with the person having a strong belief that cannot be changed or amended with facts of evidence. In the context of déjà vu, forms of delusion involve the misleading effects of perception resulting from illusions.
An illusion is a distortion of the senses resulting from a skewed perception of reality, which is common for many people to experience in the context of déjà vu. Various illusions manifest through our senses (excluding vision) when experiencing déjà vu. Many physical details that seem credible, however, can soon be discredited; in this way, déjà vu is akin to a poorly-executed magic trick.
Contrary to popular belief, déjà vu is not a memory error. Neuroscientists have made significant progress in unraveling the neuroscience behind déjà vu, although no single agreed-upon model exists. According to O'Connor, déjà vu occurs when brain areas, such as the temporal lobe, send signals to the frontal decision-making regions, indicating that an experience is repeating itself.
The frontal regions then evaluate the consistency of this signal with past experiences. If there is no prior experience, the realization of déjà vu occurs. O'Connor explains, "Experiencing déjà vu is probably a good thing for most people. It's a sign that the fact-checking brain regions are working well, preventing you from misremembering events."
Factors Influencing Déjà Vu
Several factors can influence the occurrence of déjà vu. Fatigue and stress have been identified as potential contributors. When the brain is tired, its internal neuronal systems may struggle to regulate themselves, leading to a higher likelihood of misfirings and the sensation of déjà vu. O'Connor notes, "When your brain is fatigued like this, your neuronal firing is more likely to be a bit off and result in déjà vu."
Dopamine, a neurotransmitter associated with signaling familiarity, also plays a role in déjà vu experiences. O'Connor explains, "Dopamine is what’s called an excitatory neurotransmitter. And when we talk about the brain regions signaling familiarity, those neurons would have dopaminergic action." This may explain why drugs that affect dopamine levels, both recreational and medicinal, often induce elevated reports of déjà vu.
Age is another factor that influences the frequency of déjà vu experiences, as younger people tend to experience it more frequently than older individuals. This can be attributed to stronger neural activity and healthier fact-checking frontal regions in younger brains. As we age, our ability to notice errors, including instances of déjà vu, may decline. O'Connor remarks, "It’s exciting that younger people get more déjà vu; older people are normally expected to have more memory quirks."
Déjà vu continues to capture our curiosity, and thanks to the work of researchers like O'Connor, we are gaining a deeper understanding of this intriguing phenomenon. Déjà vu goes beyond a simple memory fault; it reflects the intricate workings of our brains.
Link to Psychology today article https://www.psychologytoday.com/us/blog/brain-reboot/202312/the-fascinating-science-of-deja-vuLinks to an external site.
Can Science Explain Deja Vu?
We associate the feeling of déjà vu with mystery and even the paranormal because it is fleeting and usually unexpected. The very things that intrigue us about déjà vu are the same things that make it hard to study.
Déjà vu could be a memory phenomenon. Scientists have tried to effectively recreate déjà vu in the lab. In a 2006 study by Leeds Memory Group, researchers would first create a memory for patients under hypnosis. That memory was usually something simple like playing a game or looking at a printed word in a certain color. Then patients in the different groups were given a suggestion to either forget or remember the memory, which could later trigger the sense of déjà vu when they encountered the game or word.
Other scientists have attempted to bring on déjà vu using virtual reality. One study found that participants reported experiencing déjà vu when moving through the virtual reality Sims video game when one scene was purposefully created to spatially map to another. (For example, all of the bushes in a virtual garden were replaced with piles of trash to create a junkyard with the same layout.)
These experiments have led scientists to suspect that déjà vu is a memory phenomenon. We encounter a situation that is similar to an actual memory, but we can’t fully recall that memory. So our brain recognizes the similarities between our current experience and one in the past. We're left with a feeling of familiarity that we can’t quite place.
Beyond this general explanation, there are dozens of theories that attempt to explain why our memories might malfunction in this way. Some say it’s like a short in the circuits in our brain leading to long- versus short-term memory so that new incoming information goes straight to long-term memory instead of making a stop in the short-term memory bank. Others blame the rhinal cortex—the area of the brain that signals that something feels familiar—for somehow being triggered without the memories to back it up.
Another theory is that déjà vu is associated with false memories—memories that feel real but aren’t. This form of déjà vu would be similar to the feeling when you can’t differentiate between something that really happened versus a dream. However, researchers have begun to push back on this idea.
One study used functional Magnetic Resonance Imaging (fMRI) to scan the brains of 21 participants as they experienced a kind of lab-induced déjà vu. Interestingly, the areas of the brain involved in memory, like the hippocampus, were not triggered as we would suspect if the feeling was linked to a false memory. Instead, the researchers found the active areas of the brain were those involved in decision-making. They interpret this result to mean that déjà vu could instead be a result of our brains conducting some form of conflict resolution. In other words, our brain checks through our memories like a rolodex looking for any conflict between what we think we’ve experienced versus what actually happened to us.
https://www.scientificamerican.com/article/can-science-explain-deja-vu/Links to an external site.
https://www.sleepfoundation.org/parasomnias/night-terrorsLinks to an external site