Déjà vu is the sensation of having been in the same scenario previously. This is a French expression that literally means “already seen.” Although some people interpret déjà vu in a paranormal context, conventional scientific methodologies dismiss déjà vu as “precognition” or “prophecy.”
Experts estimate that two-thirds of us have experienced déjà vu at least once in our lifetimes. While there appears to be no gender difference in the occurrence, age appears to be a factor. Déjà vu occurrences decrease drastically as people become older; in fact, most reports come from persons between the ages of 15 and 25, prompting some to speculate that déjà vu is linked to brain development. We now know that the brain isn’t fully formed until the age of 25, maybe even later. People with a greater level of education and socioeconomic status, as well as those who see more movies and travel frequently, are more likely to have déjà vu. These statistics make sense if déjà vu is all about recognition based on familiarity: Travel is more prevalent among those with greater incomes, and it allows them to see new physical sites that may create a sense of familiarity. However, just because something can’t be remembered doesn’t imply the memory isn’t still ‘in there’; it usually is, and it’s just not being accessed. These kinds of recollections could be the source of déjà vu’s sensation of familiarity. Deja vu is also more likely to occur when a person is stressed or tired, according to research. According to a 2010 study, people who remember their dreams regularly have greater déjà vu occurrences. Dreams have a reputation for being unreliable guides to reality. When you combine that with our brains’ already flawed memory system, it’s easy to understand how the two could interact to generate a sense of familiarity; perhaps you dreamed it, or something similar. Dream déjà vu is actually referred to as déjà reve, French for “dreamed before.” Approximately 86 percent of college students polled in a study report recalling events from their dreams. Cleary says this happens when you have a dream about something you’ve done, but just recall the dream, not the action itself.
Because déjà vu is so unpredictable, researching it has proved tough. That’s why some scientists are focusing their attention on epilepsy patients’ brains, particularly those who have recurrent déjà vu during the “auras” that occur right before a seizure.” Patients with epilepsy who have déjà vu are more prone to have seizures in the medial temporal area of the brain. This part of the brain also handled memory. In these investigations, patients report two sorts of seizure experiences: one is a feeling of déjà vu familiarity, and the other is a more vivid and comprehensive remembrance of a past occurrence. This is referred to as déjà vécu, or “having already lived.” Some argue that the two are related, with déjà vu being a low-level kind of failed recollection.