Jeff walked into Psychology class on Monday feeling happy about the upcoming Christmas Break. He said hello to Mrs. Smith, and sat down in his seat. As soon as he had sat down, Eric Johnson said, “Hey, my paper is not very good.” Jeff looked around and got an eerie feeling that he had experienced this moment before. Everything at that instance seemed to be repeating itself: the loudness of the room, the lighting, the mood…everything. Jeff said to himself “Wow, I just had Déjà vu.”
This example may seem like a common story experienced by most people. What it is describing is the sensation of “Déjà vu”. Déjà vu is “any number of hard-to-explain sometimes upsetting occurrences of unexpected recognition, in which the person involved has trouble identifying an antecedent for the events and/or places which seem so strangely and intensely familiar.” (Johnson, 1) Déjà vu has been defined as “familiarity without awareness”. In this paper, many different explanations for Déjà vu will be presented through numerous articles specifically about the phenomenon. Also, Déjà vu will be defined further through examples and anecdotes.
The term déjà vu is from the French meaning “already seen.” The medical term for the phenomenon is Paramnesia, meaning “the illusion of remembering scenes and events when experienced for the first time.” There are seven major phenomenological classifications of the déjà vu experience: a disorder of memory, a disorder of ego state, an ego defense, a temporal perceptual disturbance, a recognition disorder, a manifestation of epileptic firing, or a subjective paranormal experience.
One explanation for déjà vu is a lengthened period of time between the signals of both eyes. Experimentation has established that the human brain can only distinguish between two events if they occur .025 seconds apart. So if two events happen .024 seconds or less apart, then the brain would perceive the two events as one. In people with normal vision, the signals from the eyes are transmitted through the optics nerves, and the signals arrive at the same time, or if there is a slight discrepancy in the arrivals, the transmissions arrive well within the .025 second maximum time interval. The brain then interprets the signals as two slightly different views of the same scene, giving the person the impressions of a single event, which enables depth perception.
If a person had an impaired signal path in one of his or her eyes, one of the transmissions would arrive more than .025 seconds after the other. The brain wouldn’t necessarily interpret the signals to be the same scene and the brain would think that it was a Déjà vu experience. An native way that this could occur would be that the optic processing centers of the brain had a temporary flaw or impairment, a delay in the processing of the separate transmissions would be the outcome of such an impairment.
Most individuals have optic nerves that transfer the visions within the .025 second timeframe. The two sets of visual information arrive at the cortex and are perceived as one single event. If these individuals had a slightly longer timeframe, then they would have a slight awareness of déjà vu sensations. If those same individuals had much longer transmission timeframes, they would almost be living one continuous déjà vu experience. When humans are babies, their brains establish the “time window” of .025 second or whatever else was needed to make the world seem logical and correct. People who never have this occur would have déjà vu experiences every day of their lives. There are probably no surviving individuals who continuously experience déjà vu, but such people with unusually long time differentials would have occasional déjà vu , especially in times of emotion or rapid activity.
Another explanation for deja vu comes from the model of a hologram. In a hologram, each point in the image contains all of the information to complete the picture. “Even the smallest fragment will give the complete picture,” says Herman Sno, a psychiatrist at De Heel Hospital outside Amsterdam who has made an extensive study of the scientific literature on déjà vu. ‘But the smaller the fragment, the less sharp the picture will be.” If memories are stored in the brain as holograms, with all of the images, sounds, feelings, and emotions compiling one object, then each part of the memory contains all of the sensory and emotional data needed to recall the entire experience. One single detail- the pain of a knee scrape, for example, or the sound of a soccer ball being kicked- could possibly evoke the complete remembered scene. According to this hologram model, déjà vu would occur when even one detail from a past experience is repeated, and this detail is so vivid that it recalls a whole memory from the past, even if the other details of the present situation don’t match up. “As a result of the mismatching,” says Sno, “the brain mistakes the present for the past. You feel certain you’ve seen the picture before.” (Geary, 1)
The term “déjà vu” is a general term that is applied to the whole experience that people are used to having. But déjà vu means, “already seen.” It doesn’t apply to already heard, already felt, etc. This is a common mistake that many people commit when they use “déjà vu” in this way. If fact, there are nineteen different specific terms that all apply to the misinterpreted “déjà vu” term. Some of them are “deja entendu” meaning already heard, “deja eprouve” meaning already experienced, and “deja fait” meaning already done. The word “deja” means “already”, so the real meaning of déjà vu only applies to the experience that involves a repeated sight.
Déjà vu has been connected with temporal lobe epilepsy. People with epilepsy can have a déjà vu experience right before a temporal lobe epileptic attack. When suffering an epileptic seizure they can experience déjà vu during the actual seizure activity or in the moments between convulsions.
There have been many studies of the déjà vu theory. The occurrence of the déjà vu experience depends on the definition of déjà vu being used, the measuring instrument, and the recall and recognition of the experience by the subject being interviewed. There have been 16 different studies on déjà vu before the 1980’s. The only ones using adequate sampling were two by Neppe which used a complicated screening process and questionnaire for the déjà vu experiences. About 70% of the population seems to report a time when they had a déjà vu experience.
Déjà vu occurs in individuals with and without a medical condition. Because of this there is much speculation as to how and why this phenomenon happens. Several psychoanalysts attribute déjà vu to some simple fantasy or wish fulfillment, while some psychiatrists think it’s due to mismatching in the brain that causes the brain to mistake the present for the past. Many parapsychologists believe it is related to a past-life experience.
The most believable explanation for déjà vu is that it is due to a lapse in the period of time between the signals of both eyes. This has some evidence of being true, and it follows Ockham’s razor: “The simplest explanation tends to be the right one.” Whether it is a slippage of timing, a metal version of a hologram or something else entirely, déjà vu will remain one of the mind’s most tantalizing and elusive phenomenon. Jeff sat at his computer and realized, “Wait a minute, I feel like I have written this paper before!” Was it déjà vu? No, it was due to the fact that his computer froze when he was half-way done with the paper, so in essence he had written the paper before. A simple yet effective explanation for the déjà vu phenomenon.
