(ORDO NEWS) — Have you ever had the unusual feeling that you have already faced the exact same situation before, although this is not possible?
Sometimes it may even seem that you are reliving something that has already happened. This phenomenon, known as déjà vu (French for “already seen”), has puzzled philosophers, neuroscientists, and writers for a very long time.
In the late 19th century, many theories emerged as to what could cause déjà vu. People thought it might be due to a mental dysfunction or perhaps a brain problem.
Or maybe it was a temporary glitch in the normal functioning of human memory. But this topic did not reach the realm of science until recently.
Transition from paranormal to scientific
At the start of this millennium, a scientist named Alan Brown decided to review everything researchers had written about déjà vu.
Much of what he could find had a paranormal connotation associated with the supernatural – things like past lives or psychic abilities.
But he also found studies that asked ordinary people about their experiences of déjà vu. From all this work, Brown was able to draw some basic conclusions about the déjà vu phenomenon.
For example, Brown determined that approximately two-thirds of people experience deja vu at some point in their lives.
He determined that the most common trigger for déjà vu is a scene or place, and the next most common trigger is a conversation.
He also reported hints for about a century in the medical literature of a possible link between déjà vu and certain types of seizure activity in the brain.
Brown’s review acted as a catalyst for scientists investigating the phenomenon of déjà vu.
Testing the déjà vu effect in the psychology lab
Inspired by Brown’s work, a research team led by Anne Cleary, a professor of cognitive psychology at Colorado State University, began conducting experiments aimed at testing hypotheses about the possible mechanisms of déjà vu.
Scientists were testing a nearly century-old hypothesis that déjà vu can occur when there is a spatial similarity between the current scene and a scene that has not been replayed in your memory. Psychologists have called this the Gestalt familiarity hypothesis.
Imagine, for example, that you are walking past a nursing station in a hospital ward on the way to visit a sick friend. Although you have never been to this hospital before, a strange feeling strikes you.
The main reason for this feeling of déjà vu may be that the layout of the scene, including the placement of furniture and individual items in the space, has the same layout as another scene you have seen in the past.
Perhaps the layout of the post the furniture, the items on the shelf, the way it connects to the corners of the hallway is the same as the layout of the tables in relation to the signage and furniture in the hallway at the entrance to the school event you attended a year ago.
According to the Gestalt Familiarity Hypothesis, if a previous situation similar to the current one does not come to mind, you may be left with only a strong sense of familiarity with the current one.
To explore this idea in the lab, the scientists used virtual reality to put people into scenes.
In this way, the researchers could manipulate the environment in which people were located – some scenes had the same spatial layout, but otherwise differed from each other.
As predicted, déjà vu was more likely to occur when people were in a scene that contained the same spatial arrangement of elements as the previous scene they had watched but did not remember.
This study suggests that one contributing factor to déjà vu may be the spatial similarity of the new scene to one that is stored in memory but cannot be consciously recalled to memory at the moment.
However, this does not mean that spatial similarity is the only cause of déjà vu.
It is very likely that many factors can contribute to a scene or situation appearing familiar. Additional research is currently underway to explore additional possible factors influencing this mysterious phenomenon.
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