Wait...Have I Been Here Before? The Neuroscience Behind Déja Vù

 Mary Casey

HST 401

Professor Horgan

30 April 2026

Wait…Have I Been Here Before?

The Neuroscience Behind Déja Vù

Introduction

It’s Wednesday, and you’re sitting in your 11 am class zoning in and out of the professor’s lecture. Suddenly, you feel that something is…off. The professor says something in a certain tone, someone laughs a certain way, and someone else sneezes, all in that order. For a moment you freeze. Wait. I’ve been in this exact moment before. It’s hard to explain when or where, but it feels completely real. You feel you know what happens next. The next thing you know, the feeling is gone.

Such an experience is known as déja vù, French for “already seen.” It is something that most people, around 60-80%, experience at least once in their lifetime (Labate et al., 2018). Although it lasts only a few seconds, it raises the interesting question: why does my brain sometimes feel like it remembers something, something that never even happened in the first place? 

Researchers believe that déja vù is not something that is supernatural, but an error in the brain’s memory-processing system. It happens when there is a mismatch between familiarity and memory, and understanding why it happens not only explains the experience itself, but also reveals more about how the memory works.

Déja Vù as a Memory Error

A clear way to define déja vù comes from Chris Moulin, a neuropsychologist at the Laboratoire de Psychologie et NeuroCognition at the Institut Universitaire de France. He describes it as “a feeling of familiarity with a present moment combined with the awareness that the feeling is false” (Moulin, 2013). In other words, you do not just feel familiarity, you know you shouldn’t feel the familiarity. 

The understanding narrows down to two types of memory, which are familiarity and recollection. Familiarity is a quick, automatic feeling that something is known, and recollection is when you can actually remember details, like where you have seen something before. 

Usually, familiarity and recollection work together; however, in déja vù, something turns amiss. The brain triggers familiarity, but recollection does not follow behind, so the brain is saying this feels familiar, and I don’t know why. Such a mismatch creates what researchers call an “illusion of recognition” (Brown, 2003; Moulin, 2013). Instead of a real memory, déja vù is a moment where the brain misinterprets a familiarity signal. 

The Déja Vù Mechanism in the Brain

The concept of illusion of recognition is supported by neuroscience research, such as the fact that déja vù is linked to activity in the temporal lobe. It is particularly involved in areas associated with memory such as the hippocampus and the parahippocampal cortex (Labate et al., 2018). 

The hippocampus plays an important role in retrieving memories, whereas the parahippocampal cortex helps detect familiarity. During a déja vù experience, the familiarity system appears to activate without the memory system backfires on retrieving a source. Thus, the brain recognizes something but cannot explain why. This creates a conflict between recognition and recall, which is what we know as déja vù.

The conflict is supported by evidence coming from temporal lobe epilepsy (TLE). Many individuals with TLA report déja vù as an “aura” or warning sign before a seizure. In such cases, abnormal electrical activity in memory related brain regions cause intense feelings of familiarity (Labtate et al., 2018).

Déja vù in epilepsy often feels different from personal and typical experiences. Patients report stronger emotions, including fear or dissociation, which suggests that déja vù is tied to how many circuits are functioning rather than it being a random event.

Experimental Evidence

The déja vù experience has been able to be recreated in controlled experiments, and in such studies, participants are shown a scene and later shown a new scene with similar layout or structure. Although they cannot recall the original scene, they report a sense of familiarity.

This experiment provides information about the brain’s high sensitivity to patterns. When the brain detects something structurally familiar to a past experience, it generates a familiarity signal even without retrieving a specific memory (Brown, 2003). 

Such a claim explains why certain environments can feel strangely familiar, like empty hallways, hotel corridors, or other “liminal spaces.” You may not have been there before, but you recognize the pattern.

Figure 1. An example of what one calls a “liminal space,” which is a place someone feels they have been before even without actually have been there.

    The ability to recognize patterns without putting a finger on the source does not only occur in controlled experiments, but can also be observed in broader cultural experiences.

Cultural Déja Vù

Déja vù is explained through a psychological phenomenon, but there is a similar sense of familiarity that can arise outside of direct memory, called cultural déja vù. Cultural déja vù is an experience where something feels familiar not because it has been experienced personally, but because it resembles patterns encountered over time in a repeated manner.

In media and storytelling, ideas and structures are constantly used, and cultural theorists describe such as a form of residual familiarity. Residual familiarity is when elements from past narratives continue to shape new ones (Pop, 2019), and as a result, people may experience a sense of recognition even when encountering something new.

For example, many films follow similar narrative structures, such as the “hero’s journey.” Such narratives make new stories feel familiar despite being novel, and, and comparison, recurring visual environments (such as long hallways, empty rooms, or symmetrical spaces) can evoke recognition due to reflecting patterns the brain has already learned to identify.

There is a psychological approach suggesting that familiarity can occur independent of memory retrieval (Brown, 2003; Moulin, 2013). In both cases, the brain responds to patterns rather than specific past experiences.

Such a connection strengthens the concept of déja vù not simply being a memory error, but a part of a wider system through which the brain detects familiarity, Whether triggered by neural processes or repeated cultural experiences, the exposure reflects the brain’s tendency to recognize patterns even when it cannot explain them.

Speculative Theories and Misconceptions

Déja vù feels so peculiar that it has been often linked to more speculative explanations. Ideas about parallel universes, time loops, or simulation theory (Bhattacharjee, n.d.) have been discussed over many years, and they suggest that déja vù may be evidence of alternate realities or “glitches in time.” 

These ideas are fascinating, and it is always enjoyable to wonder. However, they are not supported scientifically. Current research strongly suggests that déja vù is strictly a cognitive and neurological phenomenon, not a supernatural one. Still, people turn to these explanations (myself included), which highlights just how powerful and convincing the experience of déja vù can be. Nevertheless, scientific evidence can only go so far, and looking beyond reality can lead to some groundbreaking discoveries.

Why it Matters

Déja vù may seem like a random or meaningless experience at first, but studying it reveals important insight on how the brain functions.

Most people think of memory as a kind of recording, as if the brain simply stores events and plays them back later like a VHS tape. However, déja vù indicates the idea that memory is something the brain actively constructs and evaluates in real time. 

The human brain is constantly trying to determine if something is familiar or not, and déja vù occurs when that system makes an error. Understanding the brain’s functions when it comes to déja vù helps scientists study how recognition memory works, how false memories form, how perception and memory interact, and how neurological conditions affect cognition. It also suggests that our sense of reality is not always as stable as we assume, and if the brain can produce a strong sense of familiarity without a real memory, then what feels real is not always accurate.

Conclusion

The déja vù experience is not only a strange moment but vital insight into how the brain works. It occurs when the brain’s familiarity with certain elements activate, but the memory system cannot provide an explanation, which elucidates the powerful illusion that the present has already happened. Likewise, similar feelings of familiarity can emerge from repeated patterns in culture, demonstrating that familiarity does not always mirror personal experience.

The next time you have this bizarre feeling at your 11 am class on a Wednesday, zoning in and out of your professor’s lecture in a certain tone with someone laughing or sneezing in the background, you are watching your brain try to determine whether the present feels like the past.

References

Moulin, C. J. A. (2013). The cognitive neuropsychology of déjà vu. Psychology Press.

Labate, A., Gagliardi, M., Sturniolo, M., et al. (2018). Insight into epileptic and physiological déjà vu from a multicentric cohort study. European Journal of Neurology, 25(6), 888–e66. https://doi.org/10.1111/ene.13624

Bhattacharjee, D. (n.d.). The Mandela effect, déjà vu and possible interactions with the parallel world [Preprint]. ResearchGate.

Brown, A. S. (2003). A review of the déjà vu experience. Psychological Bulletin, 129(3), 394–413. https://doi.org/10.1037/0033-2909.129.3.394

Pop, D. (2019). Residual humanities: From the cultural déjà vu to reclaimed narrations. Ekphrasis. Images, Cinema, Theory, Media.