Deja Vu: Decoding the Brain’s Glitch in Reality
Scientifically Reviewed · Dr. Marwa Abd-Alazim · August 13, 2026
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Deja Vu: An Overview of the Phenomenon
Deja vu is a French expression for “already seen” that is used to describe the feeling of familiarity one experiences when experiencing something for the first time (Hirshorn, 2018). It is a phenomenon that has been reported by approximately two-thirds of the population in the United States. This article provides an overview of the phenomenon of deja vu and its theoretical explanations.
Deja vu is a feeling of familiarity that is often accompanied by a sense of eeriness or strangeness (Herzog et al., 2019). It is typically spontaneous and does not necessarily have to be associated with a particular event or situation. The experience is usually brief, lasting a few seconds, and is often followed by a feeling of confusion (Hirshorn, 2018).
Many theories have been proposed to explain the phenomenon of deja vu. One of the most popular explanations is the memory transfer hypothesis, which suggests that deja vu is caused by an overlap between two different memories (Herzog et al., 2019). The overlap occurs when the experience is similar to a past experience, but it is not recognized as such, leading to the feeling of familiarity. Other explanations include the serotonin hypothesis, which suggests that deja vu is caused by a decrease in the neurotransmitter serotonin, and the temporal lobe hypothesis, which suggests that deja vu is caused by a malfunction in the temporal lobe of the brain (Hirshorn, 2018).
Despite its prevalence, deja vu remains poorly understood. Further research is needed to understand the underlying mechanisms that cause the phenomenon and its psychological implications.
References
Herzog, M., Glaubitz, B., & Koppe, G. (2019). The phenomenology of déjà vu: An integrative review. Consciousness and Cognition, 68, 58-67.
Hirshorn, E. (2018). What is deja vu? Understanding the phenomenon. Psychology Today. Retrieved from https://www.psychologytoday.com/us/blog/the-superhuman-mind/201809/what-is-déjà-vu-understanding-the-phenomenon
