Déjà Vu Explained: What Happens in the Brain When Moments Feel Familiar?

You are in a room which you have never before gone to, hearing a conversation that you have never before listened to, yet there is a strange sense of familiarity. For a few seconds you have the impression that you already know what is going to happen. You can’t remember when this situation took place, but you are quite sure that it did. And then, just as quickly as it had come, the sensation vanishes, leaving you puzzled about what had just occurred.

We have all come across this odd phenomenon, called déjà vu, at some stage. It is especially intriguing because of the contradiction it presents: although we are aware that the situation is new, our mind still makes us feel as though we have experienced it before. The experience can be so convincing that some people link it to having lived through it in a previous life. Others associate it with existing in parallel universes or even seeing a glimpse of the future.

However, perhaps the more interesting question isn’t whether or not we have already lived through the moment. Instead, it is why our mind causes us to feel as if we have. Psychology has proposed a number of possible explanations. These relate déjà vu to memory, perception, and the way we assess our own experiences. Instead of being just an unusual sensation, déjà vu gives us a chance to gain an understanding of how the mind puts together our experience of reality (Brown, 2003; Cleary, 2008).

The Difference Between Remembering And Feeling Familiar 

Suppose you think of a person you last saw and have a feeling that you have seen them before, even though you can’t recall when or where. You may know their face, their voice, or even the way they move. However, you may still find it difficult to remember where this sense of familiarity comes from. Now consider the case of meeting an old friend and immediately recalling your shared school days. In both instances there is a matter of recognition, but in only the second case do you have a clear memory of the past. 

It is important to appreciate this difference when trying to understand the phenomenon of déjà vu. Some psychologists (Skinner & Fernandes, 2007) point out the distinction between familiarity and recollection. Familiarity is the feeling that something is already known. In contrast, recollection involves retrieving specific details from a previous experience. Although the two can happen at the same time, they do not necessarily have to be based on the same mental processes.

Déjà vu can take place even when there is a sense of familiarity without a corresponding memory to account for it. For example, suppose you are entering a hotel lobby for the first time.ie. You might not be aware of having visited that place previously, but certain aspects of the current environment still give you a feeling of familiarity. 

Cleary (2008) looked into the possibility that déjà vu could result from a form of recognition based on familiarity. In this case, a person feels familiar with something without being able to identify its source. This helps to account for the fact that the sensation can be very convincing even though we are unable to recall a specific memory of the situation. The key point is that feeling as if we remember something does not mean that we actually have a memory of it. In fact, at times, the feeling comes about before we can work out where it originated.

How Does Thinking Play A Part In Déjà Vu? 

1. Memory: The effect of the past on the present 

We usually regard memory as something that we intentionally bring to mind, such as remembering a conversation, recalling an experience from our childhood, or attempting to recover an answer in an exam. Yet earlier experiences can also affect our reaction to new situations even if we do not consciously recall them. For example, if you walk into a classroom for the first time, you might feel as though you already know its layout. The arrangement could be similar to that of your previous school classroom, even if the walls, the furniture, and the people are different. As a result, your mind might detect the similarities between the two environments without having to call up a specific memory of the original one.

Cleary and colleagues in 2012 looked into this possibility by means of virtual reality experiments. The participants were exposed to unfamiliar scenes that differed in how similar they were to scenes they had previously encountered. When the spatial layout of a new scene was similar to that of an earlier one, the participants were more likely to say that they felt familiar. As a result, they experienced déjà vu-like feelings, even though they could not consciously remember the earlier scene.

This indicates that the brain might respond to the similarities between experiences even if it does not recognise the source of them. Déjà vu is a reflection of similarity and results from the influence of previous experiences on current recognition. Yet, this is only one possible explanation and not a full answer. Not every instance of déjà vu can be explained by similarities between environments. Therefore, researchers continue to examine the various processes that may be responsible for the experience (Brown, 2003).

2. Attention: Didn’t we spot something before we had realised it? 

We focus on only a small part of what is around us even though there are hundreds of sights and sounds. Later on, information that has not attracted much of our attention can still affect the way we experience a situation. Picture yourself strolling around a market as you’re speaking to a friend. You don’t really take much notice of what’s around you. However, at that moment, you look up and suddenly realise that you have seen this scene before.

A possible reason for this is that a first impression, which is processed with limited attention, might be responsible for the sense of familiarity we get when we then focus more closely on the situation. Brown (2003) examined attentional explanations together with memory-based explanations of déjà vu. This possibility shows a significant link between attention and cognition. In other words, we are not always aware of all the things that affect our experience.

Instead, what we notice, what we fail to notice, and the way information is processed can influence our perception of the present moment. However, the role of attention in cases of naturally occurring déjà vu is still unclear. The example given here describes a proposed mechanism, not an explanation that applies to all instances of the phenomenon. 

3. Metacognition: Why do we question our own experience? 

What makes déjà vu so interesting is that we can have a strong sense of familiarity even though we know the situation is new. This leads us to the concept of metacognition, which is the ability to keep an eye on and assess our own mental processes. In ordinary life, metacognition enables us to realise that we aren’t sure about an answer. It also allows us to question whether we accurately remember something or recognise that our first judgment could be incorrect.

Suppose you hear a story being told and are sure that you have heard it before. You attempt to remember the conversation, but no particular memory surfaces. Although you are aware of the sense of familiarity, you can’t determine where it comes from. Aitken et al. (2023) put forward a theory of déjà vu based on conflict, stating that the experience might occur when the feeling that something is familiar clashes with the parallel judgement that it is new.

Put simply, one part of our thinking says, “I know this,” while another says, “I have never experienced this before.” The important point is that the mind does not always arrive at a single, unified judgement about an experience. Different processes can lead to conflicting signals, and we may become conscious of this conflict. Déjà vu might thus provide some insight into the way we keep an eye on our own memories and assess the reliability of our mental experiences. 

What Happens In The Brain During Déjà Vu? 

Scientists think déjà vu happens when the brain checks memories and gets mixed signals. The brain might mistake a new experience for something familiar, even though it has not happened before. This could come from a small timing error between how the brain handles short-term and long-term memories. As a result, a new event feels strangely familiar. 

If we are to understand déjà vu, then we should also look at the different areas of the brain that are concerned with memory and recognition. The hippocampus is important for forming and retrieving memories of events together with their context. Other areas in the vicinity, for example, the perirhinal cortex, are involved in recognition and the feeling of familiarity (Skinner & Fernandes, 2007).

It has been suggested that déjà vu might result from a discrepancy between the signals which produce a sense of familiarity and the processes that enable us to determine the source of a memory. Nevertheless, the exact neurological explanation is still being investigated (Aitken et al., 2023).  Clinical research also offers further insights. Déjà vu may happen in individuals with temporal lobe epilepsy, and some of these cases have been linked to changes in the way familiarity is processed (Martin et al., 2012).

Bartolomei et al. (2004) examined the role of the rhinal cortex in déjà vu and in experiences related to memory by using cortical stimulation. Yet a normal instance of déjà vu should not be taken as proof of a neurological disorder. The phenomenon also occurs in people who do not have epilepsy, and neurological findings from clinical groups cannot be generalised to every person who experiences it (Brown, 2003). What these studies show is that déjà vu is not merely an abstract psychological curiosity. Instead, it gives researchers a means of investigating the connection between memory, subjective experience, and the neural processes involved in cognition.

Does Déjà Vu Mean We Can Tell What Will Happen Next? 

The reason déjà vu seems so mysterious is that it may make us feel as though we know what is going to happen next. For instance, in a conversation we might have the impression that we already know what the other person is going to say. If the next few seconds turn out as we expected, the experience can come across as almost supernatural. Yet familiarity does not mean prediction.

A situation that seems familiar can lead to an expectation about how it should develop, without actually involving any knowledge of the future. In 2021, Cleary and others looked into the relationship between déjà vu and the feeling of prediction. They examined how familiarity is connected with the impression that one knows what will happen next. As a result, this type of study enables psychologists to investigate the experience scientifically without assuming that déjà vu actually has predictive power.

Why Is It Important To Understand Déjà Vu? 

Déjà vu serves as a useful reminder that the way we perceive reality is the result of several interacting cognitive processes. The memory process affects recognition, attention decides which information we deal with, and metacognition enables us to assess our experiences. It also casts doubt on the idea that our minds always give us reliable accounts of our feelings. For example, it is possible to feel certain that we know a place even if we can’t recall it. Similarly, we may feel a sense of familiarity without being able to identify where it came from.

Research indicates that such experiences arise out of the complex interaction between recognition, memory retrieval, and cognitive control (Cleary, 2008; Aitken et al., 2023).  At the same time, déjà vu is still hard to study since it is short, unpredictable and difficult to reproduce reliably in laboratory conditions. Although experiments can produce some elements of familiarity, they do not necessarily reproduce the full experience of déjà vu. This is because déjà vu occurs in normal situations.

For example, O’Connor and Moulin (2013) found that the déjà vu experiences of healthy participants had no relationship to laboratory tests of recollection and familiarity. These tests were carried out using word stimuli. This finding shows how difficult it is to explain the phenomenon on the basis of a single experimental test. The research therefore stimulates interest but does not allow for premature conclusions. There are a number of possible explanations for déjà vu, and no single theory has yet accounted for all instances of it.

Conclusion 

What is most interesting about déjà vu is not the sensation that we have already lived through a particular moment. Instead, it is the fact that we can have that sensation without knowing where it originated from. The mind always interprets the world by means of memories, perceptions, expectations, and judgments. Generally speaking, these processes function together smoothly.

There are, nevertheless, some instances in which they result in an experience that seems familiar even though we are unable to determine its source.  Déjà vu gives us a look at this complexity. It shows us that remembering and recognising are not the same thing. Familiarity can be present even in the absence of conscious recollection. Additionally, a strong feeling does not necessarily provide a correct account of reality.

The next time a new situation seems strangely familiar, maybe the more interesting question is not ‘Have I already experienced this?’ but ‘What is going on in my mind that makes me feel as though I have?’ This change in perspective turns a brief and mysterious experience into a chance to grasp one of the most intriguing features of what it means to be human. It highlights the way our minds construct, interpret, and at times doubt our own reality.

References +

• Aitken, C. B. A., Jentzsch, I., & O’Connor, A. R. (2023). Towards a conflict account of déjà vu: The role of memory errors and memory expectation conflict in the experience of déjà vu. Neuroscience & Biobehavioral Reviews, 155, Article 105467. https://doi.org/10.1016/j.neubiorev.2023.105467 
• Bartolomei, F., Barbeau, E., Gavaret, M., Guye, M., McGonigal, A., Régis, J., & Chauvel, P. (2004). Cortical stimulation study of the role of rhinal cortex in déjà vu and reminiscence of memories. Neurology, 63(5), 858–864. https://doi.org/10.1212/01.WNL.0000137037.56916.3F 
• 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 
• Cleary, A. M. (2008). Recognition memory, familiarity, and déjà vu experiences. Current Directions in Psychological Science, 17(5), 353–357. https://doi.org/10.1111/j.1467-8721.2008.00605.x 
• Cleary, A. M., Brown, A. S., Sawyer, B. D., Nomi, J. S., Ajoku, A. C., & Ryals, A. J. (2012). Familiarity from the configuration of objects in 3-dimensional space and its relation to déjà vu: A virtual reality investigation. Consciousness and Cognition, 21(2), 969–975. https://doi.org/10.1016/j.concog.2011.12.010 
• Cleary, A. M., McNeely-White, K. L., Huebert, A. M., & Claxton, A. B. (2021). Déjà vu and the feeling of prediction: An association with familiarity strength. Memory, 29(7), 904–920. https://doi.org/10.1080/09658211.2018.1503686 
• Kim, H. (2021). Imaging recollection, familiarity, and novelty in the frontoparietal control and default mode networks and the anterior-posterior medial temporal lobe: An integrated view and meta-analysis. Neuroscience & Biobehavioral Reviews, 126, 491–508. https://doi.org/10.1016/j.neubiorev.2021.04.007
• Martin, C. B., Mirsattari, S. M., Pruessner, J. C., Pietrantonio, S., Burneo, J. G., Hayman-Abello, B., & Köhler, S. (2012). Déjà vu in unilateral temporal-lobe epilepsy is associated with selective familiarity impairments on experimental tasks of recognition memory. Neuropsychologia, 50(13), 2981–2991. https://doi.org/10.1016/j.neuropsychologia.2012.07.030 
• O’Connor, A. R., & Moulin, C. J. A. (2013). Déjà vu experiences in healthy subjects are unrelated to laboratory tests of recollection and familiarity for word stimuli. Frontiers in Psychology, 4, Article 881. https://doi.org/10.3389/fpsyg.2013.00881 
• Skinner, E. I., & Fernandes, M. A. (2007). Neural correlates of recollection and familiarity: A review of neuroimaging and patient data. Neuropsychologia, 45(10), 2163–2179. https://doi.org/10.1016/j.neuropsychologia.2007.03.007 
• Teale, J. C., & O’Connor, A. R. (2015). What is déjà vu? Frontiers for Young Minds, 3, Article 1. https://doi.org/10.3389/frym.2015.00001