Déjà vu is a dissociative memory experience defined as the conflict between a sense of extreme familiarity in a new situation and the realisation that this feeling is mistaken. This brief review synthesises four key studies (O’Connor & Moulin, 2006; Teale & O’Connor, 2015; Wells, O’Connor & Moulin, 2018; O’Connor, Wells & Moulin, 2021) to examine the phenomenology, neurobiological underpinnings and clinical implications of déjà vu. It summarises the déjà vu experience in visually impaired individuals, focusing on anxiety and limbic system connections.
Déjà vu, meaning ‘already seen’, is one of the most fascinating phenomena in memory research. Experienced by approximately 60–96 percent of the general population, this phenomenon is characterised by a situation feeling intensely familiar, yet the awareness that this familiarity is illogical (Brown, 2004; Teale and O’Connor, 2015). Over the past fifteen years, research led by Akira R. O’Connor, Chris J.A. Moulin and Christine E. Wells has moved déjà vu beyond being merely an interesting illusion and placed it within the context of dissociative memory mechanisms.
What Is Déjà Vu?
Teale and O’Connor (2015) define déjà vu as “the experience of a new event feeling excessively familiar, whilst being aware that this familiarity is mistaken”. This experience arises from the dissociation of the feeling of familiarity from the processes of recollection and creates a metacognitive dissonance (O’Connor et al., 2021).
In prevalence, déjà vu begins between the ages of 6 and 10, peaks between 15 and 25, and then decreases with age (Teale & O’Connor, 2015). This age pattern suggests that déjà vu is a healthy metacognitive monitoring mechanism. The young brain is better able to detect and reject erroneous familiarity signals. The frequency of experiences typically decreases from several times a week to once every few months and is multisensory in nature (involving hearing, touch and smell simultaneously).
In a study conducted by O’Connor and Moulin in 2006, MT, a 25-year-old who has been visually impaired since birth due to extreme microphthalmia, experiences classic déjà vu episodes. MT’s déjà vu experiences share the same characteristics as those of individuals without visual impairment; they last between a few seconds and thirty seconds, are triggered in the evenings whilst alone, create a sense of multisensory convergence, and are sometimes described as curious, pleasant and strange (O’Connor and Moulin, 2006).
This case directly refutes the optical pathway delay theory—which has been popular since the 19th century and claims that déjà vu is caused by the optic nerves transmitting signals at different speeds. The fact that déjà vu occurs even in the absence of an optic pathway in MT demonstrates that the experience is not dependent on the visual pathway. Instead, déjà vu indicates that familiarity mechanisms in the temporal lobe and parahippocampal regions operate in a multisensory and vision-independent manner. This finding has redefined déjà vu as a general memory error rather than a visual illusion.
Wells, O’Connor and Moulin (2018) systematically investigated the relationship between déjà vu and anxiety. In individuals with a clinical diagnosis of anxiety, déjà vu was found to be significantly more frequent, more intense and more distressing in the previous month compared to the control group. The frequency and severity of déjà vu increase during periods of anxiety.
This relationship is explained at the neuropsychological level via the theta rhythm. Hippocampal theta plays a role in both memory processing and anxiety regulation. Anxiety disrupts theta synchronisation, thereby facilitating the misinterpretation of familiarity cues. It has been emphasised that déjà vu may carry a psychogenic component in anxiety disorders and that it causes distress (Wells et al., 2018). This finding has demonstrated that déjà vu is also associated with psychiatric conditions.
Déjà vu has been situated within a broader family of dissociative memory conditions. Déjà vu is the dissociation of the sense of familiarity from reality. Similarly:
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Jamais vu: the sensation that something familiar feels unfamiliar.
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Presque vu: the feeling that an ‘aha!’ moment is about to happen, but it doesn’t actually occur.
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Prescience: the feeling of knowing the future (even though it is known to be incorrect).
All these situations reflect the dissociation between lower-level memory processes (familiarity/recall) and higher-level metacognitive evaluation. By synthesising single-case and group studies derived from temporal lobe epilepsy, anxiety and other clinical cases, it has been suggested that déjà vu arises as a result of an ‘aberrant signal’ formed in the limbic-temporal networks.
In particular, a case reported in 2021 (involving a woman experiencing frequent déjà vu following a thalamic haemorrhage) showed that the frequency of déjà vu decreased from once a day to once a week following psychoeducation and metacognitive awareness training, and her quality of life improved. This is one of the first indications that déjà vu may be a treatable symptom.
The synthesised studies explain the fundamental mechanism of déjà vu through the decoupled familiarity hypothesis: the sense of familiarity arises independently of recollective processes. Stimulation of the rhinal cortex triggers déjà vu, accompanied by theta rhythm synchronisation. Whilst the role of the hippocampus is critical, the persistence of déjà vu in blind individuals despite reduced hippocampal volume in the MT highlights the sufficiency of parahippocampal structures. The link to anxiety occurs via disruption of the theta rhythm; anxiety amplifies erroneous familiarity signals, thereby increasing the frequency and intensity of déjà vu.
A synthesis of these four studies reveals a significant paradigm shift in déjà vu research: the old vision-based theories have been abandoned, and déjà vu has been redefined as a multisensory memory phenomenon independent of vision. It has been established that psychiatric conditions such as anxiety trigger déjà vu and cause distress; the dissociative framework, meanwhile, has linked déjà vu with other metacognitive distinctions such as jamais vu, presque vu and prescience. The first successful results of psychotherapy-based interventions suggest that déjà vu may be a treatable symptom.
References
Brown, A. S. (2004). The déjà vu experience. Psychology Press.
O’Connor, A. R., & Moulin, C. J. A. (2006). Normal patterns of déjà experience in a healthy, blind male: Challenging optical pathway delay theory. Brain and Cognition, 62(3), 246–249. https://doi.org/10.1016/j.bandc.2006.06.001
O’Connor, A. R., Wells, C., & Moulin, C. J. A. (2021). Déjà vu and other dissociative states in memory. Memory, 29(7), 835–842. https://doi.org/10.1080/09658211.2021.1911197
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
Wells, C. E., O’Connor, A. R., & Moulin, C. J. A. (2018). Déjà vu experiences in anxiety. Memory, 26(5), 646–652. https://doi.org/10.1080/09658211.2018.1538418