Have you ever been in a moment that feels eerily like one you've already experienced in the past? Where every detail is identical to a situation in your memory? "Déjà vu" (French for "already seen") is explained as experiencing a certain moment that seems as if you've been there before and you're reliving the exact same situation as in your memory. Can this strange phenomenon be explained by scientific logic? Continue reading to find out!
When this unexpected feeling of experiencing the exact same moment as one that happened in the past suddenly hits you, it can be unnerving. Although it is difficult to study because déjà vu episodes are usually brief and unexpected, various theories have been hypothesized and tested in the scientific world, with many interesting results.
Laboratory Studies
One study by the Leeds Memory Group in 2006 happened in a lab where they tried to create déjà vu for the participants, then record their observations. In these hypothetical scenarios, the scientists told the participants to perform a simple task to create a memory, then instructed them to forget it, and will later test to see if they will experience the feeling of déjà vu when reencountering that moment. Based on these experiments, the scientists hypothesized that it is a memory phenomenon, where we experience something really familiar to a past event, but we cannot fully recall the memory, which leads us to believe that we're reliving the exact same moment, and an uneasy feeling of familiarity.
In another study, functional Magnetic Resonance Imaging (fMRI) was used. fMRI is a tool frequently used by psychologists that can record brain activity by allowing changes in blood flow to be viewed. Blood flows to areas of the brain when they are active, so this technique allows us to see which parts of the brain are being used during specific functions. For this study, participants were scanned by fMRI as they were experiencing déjà vu, and the results were unexpected. Areas such as the hippocampus that are involved in memory were not activated, but rather areas responsible for decision making were. This observation leads to the theory that déjà vu can be a form of resolving problems or when our brains are going through our memories to find any possible conflict concerning what we believe happened and what actually happened.
Dr. Alan Brown and Elizabeth Marsh conducted studies at Duke University and SMU where they would quickly flash photographs at participants for milliseconds at a time, so their brain would pick up the sensory information, but they would not be consciously remembering it. Afterward, they showed the participants various pictures, including those they were shown previously and those they weren't, and results show that the participants found the images they were flashed to be more familiar than those they weren't. Based on this experiment, Dr. Brown came up with the "cell phone" theory, or "undivided attention" theory, which explains that when we are distracted, our brain registers details in our surroundings but we do not consciously remember them.
Other patterns have been found in the types of people that experience déjà vu. For instance, the rates of people who say they have experienced déjà vu are the highest in the age range of 15 to 25 years old. They also occur more frequently for people who travel more and have higher education levels. Additionally, people with more active imaginations and those who remember their dreams report more déjà vu experiences.
Another report has research findings that show déjà vu is a more likely experience for individuals that are more open-minded. However, they acknowledge that their open-mindedness may be the reason why they are more likely to report their weird déjà vu experiences compared to those who are less open-minded.
Other Theories
In the past, déjà vu used to be thought of as recalling a memory from a past life. However, this theory is backed up with no evidence and is not seemingly logical. Sigmund Freud, an important figure in the history of psychology, hypothesized that déjà vu can be described as paramnesia caused by encountering things that trigger repressed memories that are extremely stressful to the conscious mind, which is why it is not retrieved as a regular memory.
Some have suggested that this feeling can be explained by a "malfunction" in our brain. Usually our brain processes memories by first storing them in our short term memory, then storing them in our long term memory. In this theory, déjà vu happens when the memory goes straight to our long term memory, causing us to feel like the instance has already happened since it is present in our long term memory.
Another theory proposes that the rhinal cortex, which is a structure in our brain that signals us when something is familiar, is triggered falsely or is unable to retrieve memories to back up the feeling. This gives us a feeling that we have been in that moment before, but we can't exactly match it to a particular memory.
Déjà vu sometimes hits us unexpectedly with no clear reason as to why. Although there is not one clear answer to why we feel déjà vu, it is an interesting phenomenon to study. Feel free to comment your experiences with déjà vu, and if this article matches them in some way!
Written by: Janice Le
References:
Devlin, Hannah. "What is Functional Magnetic Resonance Imaging (fMRI)?" Psych Central, 8 Oct. 2018, psychcentral.com/lib/what-is-functional-magnetic-resonance-imaging-fmri.
Obringer, Lee Ann. “How DéJà Vu Works.” HowStuffWorks, 30 June 2020, science.howstuffworks.com/science-vs-myth/deja-vu.htm.
Stierwalt, Everyday Einstein Sabrina. “Can Science Explain Deja Vu?” Scientific American, 23 Mar. 2020, www.scientificamerican.com/article/can-science-explain-deja-vu.
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