Deja vu: here’s what the science says

Why do people have deja vu experiences? – Atharva P., 10, Bengaluru, India

Have you ever had the weird feeling of having already experienced a situation that corresponds exactly to an event of the pasteven if it is impossible? Sometimes it can also feel like reliving something that has already happened. This phenomenon, known as deja vuintrigues philosophers, neurologists and the writers Since long time.

From the late 1800s, many theories began to emerge about what might be causing the feeling of deja vu. It was thought that it could be from mental dysfunction or possibly some type of brain problem. Or maybe it was a passing event in the normal functioning of human memory. But the subject only reached the realm of science very recently.

From Paranormal to Scientific

At the beginning of this millennium, a scientist by the name of Alan Brown decided to carry out a analysis of everything researchers had written about deja vu until there. Much of what he could find had a paranormal flavor, relating to the supernatural – things like past lives or psychic abilities. But he also found that studies have picked up experiences of deja vu in ordinary people. Through all of these articles, Brown was able to glean some basic conclusions about the deja vu phenomenon.

For example, he determined that about two-thirds of people may have experienced deja vu at some point in their lives. He found that the most common trigger for deja vu was a situation or place, and the second most common trigger was a conversation. He also reported hints, through roughly a century of medical literature, of a possible association between deja vu and certain types of epileptic seizures in the brain.

Brown’s analysis brought the subject of deja vu into the realm of more mainstream science, as it appeared both in a scientific journal generally read by experts who study cognition, and also in a book intended for researchers. His work has served as a catalyst for the scientific community to design experiments to explore deja vu.

Deja vu test in the psychology laboratory

Prompted by Brown’s work, my own research team began conducting experiments aimed at testing hypotheses about the possible mechanisms of deja vu. We have some studied a nearly century old which suggested that deja vu could occur when there is a spatial resemblance between an ongoing situation and one that has not been remembered. Psychologists have called this the Gestalt familiarity hypothesis.

For example, imagine walking past the nursing station of a hospital unit on your way to visit a sick friend. Although you have never entered this hospital before, you are struck by the feeling of having been there. The underlying cause for this deja vu experience could be that the layout of the room, including the placement of furniture and particular objects in the space, is the same as another you have visited. in the past.

The way the nursing station is located – the furniture, the objects on the counter, the way it joins the corners of the hallway – is perhaps the same as the arrangement of a set of reception tables. with posters and furniture at the entrance to a school event you attended a year ago. According to the Gestalt familiarity hypothesis, if the previous situation, which is similar in layout to the current situation, does not come to mind, there may still be a strong sense of familiarity towards it.

To study this idea in the laboratory, my team used virtual reality to place people in certain specific contexts. That way we could manipulate the environments people were in; for example, some scenes shared the same spatial layout while being distinct. As expected, the deja vu was more likely to happen when individuals were in a room whose elements were arranged in the same way in space as another room they had already seen, but which they did not remember.

This research suggests that one of the factors contributing to deja vu may be the spatial resemblance of a new situation to a scene remembered, but of which the memory is not aware at the time. However, this does not mean that this similarity is the only cause of deja vu. Most likely, there are many things that can contribute to making a scene or situation seem familiar to you. Further studies are underway to observe possible new factors playing a role in this mysterious phenomenon.