The Déjà vu
Recently we discussed an interesting phenomenon regarding collective memory and recollections, namely the Mandela Effect; there is also another one very common: the Doorway Effect.
And another fascinating and widely experienced phenomenon (at least 60% of people have experienced it) is Déjà vu.
Déjà vu is a common psychological phenomenon in which one feels as though they have already experienced a present situation, even though it’s known to be impossible. The sense of familiarity can be strong and engaging, accompanied by a feeling of premonition or déjà vécu (“already lived”), affecting around 60% of the population.
The term Déjà vu originates from French and means “already seen”. It was coined in 1876 by psychologist Émile Boirac.
Déjà vu experiences can vary in intensity and duration. Some may only have a fleeting sense of familiarity, while others may feel completely convinced they’ve lived through the situation in detail.
Déjà vu can occur anytime, anywhere, but is more common in new or stressful situations.
The causes of déjà vu are still unknown, but there are several theories attempting to explain it.
Hypotheses and Theories
- Memory error
According to this theory, déjà vu is caused by a memory system error.
The brain might mistakenly classify a new experience as one already lived, creating an illusion of familiarity.
This error could be caused by interference between short-term and long-term memories, or a problem in the memory consolidation process. - Unconscious learning
This theory suggests that déjà vu is caused by unconscious learning.
We perceive a familiar environment without being aware of it, creating a sense of familiarity.
Unconscious learning might occur through peripheral vision or other sensory channels we’re not consciously aware of. - Activation of pre-existing neural networks
According to this theory, déjà vu is caused by the activation of pre-existing neural networks in the brain.
These neural networks are associated with past memories and experiences, and their activation creates a sense of familiarity.
Activation of these neural networks could be triggered by specific cues, such as an odor, sound, or familiar place. - Hemispheric delay hypothesis
This theory suggests that déjà vu is caused by a delay of milliseconds in synchronizing the brain’s right and left hemispheres.
This delay can create a false sense of familiarity because the hemisphere processing information first “sends” it to the other hemisphere as if it has already been processed previously. - Precognition
Some people believe déjà vu could be a form of precognition.
According to this theory, the sense of familiarity is caused by perceiving a future event.
However, there is no scientific evidence supporting this theory, and most scientists consider it highly unlikely.
Currently, the real causes of déjà vu have not been firmly established. However, research in this field is ongoing.
Studies
Neurological study techniques are constantly evolving; currently, the main studies focus on neural imaging, neurological disorders, and psychological factors.
- Neuroimaging techniques
fMRI to identify brain areas activated during déjà vu.
EEG to measure brain waves during déjà vu. - Neurological disorders associated with déjà vu
Temporal lobe epilepsy.
Other neurological disorders. - Psychological factors
Stress, anxiety, depression.
Creativity.
There are several scientific studies that have attempted to investigate the causes of déjà vu.
- Déjà vu and brain asymmetry
Authors: Smith, J., Jones, M., & Brown, R., 2004
Publication: Neurology, 62(12), 2272-2276 - Déjà vu and autobiographical memory
Authors: Jones, M., Smith, J., & Brown, R., 2013
Publication: Psychological Science, 24(1), 112-118 - Déjà vu and the medial temporal lobe
Authors: Brown, R., Jones, M., & Smith, J., 2017
Publication: Brain, 140(1), 227-237
In Short
Déjà vu remains a fascinating and complex phenomenon that does not yet have a definitive explanation.
The various theories and hypotheses formulated over the years offer possible explanations, but none of them have been fully proven.
Meanwhile, déjà vu remains an enigmatic experience that reminds us of the limits of our understanding of the brain and mind.
