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Running head: THE ETIOLOGY OF DEJA VU

The Etiology of Déjà Vu: Examining Neurological, Dual Processing, Psychoanalytic, Memory, and Attentional Theories

Kyler Hood

As society witnesses the benefits of past psychological research, society gradually becomes more open to new psychological endeavors and understandings. One such phenomenon that is worth exploring is déjà vu. The nature of déjà vu makes it difficult to study, but since most of the population seems to experience it at some point, understanding the theories concerning neurological mechanisms, dual processing, psychoanalytic perspectives, memory systems, and attentional shifts will provide invaluable information about the etiology of déjà vu and other related cognitive functions.

Clarifying Déjà Vu

After years of debate, scientists finally reached a consensus that the definition provided by Neppe (1983) for déjà vu would henceforward be used. According to the definition, déjà vu occurs when someone experiences a subjectively inapt notion of familiarity in a current moment that has an unclear correlate to the past (Brown, 2003; Spatt, 2003; Findler, 1998). The experience typically occurs indoors while relaxing when around friends and is often associated with tiredness or strain. The duration of the experience usually last for approximately 10-30 seconds in people without any psychological disorder, but can last for minutes in epileptic people and for hours in people suffering from schizophrenia (Brown, 2003; Thompson et al., 2004) Researchers found no significant evidence supporting gender differences in the occurrence of déjà vu (Brown, 2003).

Researchers classified two distinct types of déjà vu for purposes of clarity: forme légere (minor form) and forme gravé (major form). The minor form occurs and dissipates rapidly and can take place in people who may or may not be experiencing pathological symptoms. The major form occurs only in people experiencing pathological symptoms, which typically results from schizophrenia or epilepsy (Sno & Linszen, 1990).

Prevalence

Brown (2003) estimates that approximately 60% of people report incidents of déjà vu. Most researchers agree with Brown that the total reported incidence of déjà vu and the frequency of déjà vu decreases with age; however, the evidence provided by Thompson, Moulin, Conway & Jones (2004) supports the hypothesis that déjà vu experiences increase with age. More research will be necessary to clarify this contradiction. Researchers do know, however, that the experience of déjà vu is correlated with higher levels of education, higher socioeconomic class, and more travel experience (Brown, 2003). The experience also correlates with several predisposing conditions including excessive worrying, dissociative neuroses, personality and mood disorders, biological brain problems, and schizophrenia. Overtiredness, excessive worry, sickness, major events influencing the affect, and drugs are also associated with the experience of déjà vu (Sno & Linszen, 1990).

Methodology Problems

Déjà vu is a subjective experience that only one individual can experience at any given point in time; as a result, researchers must realize and discuss the inherent problems used to report this phenomenon in order to gain more insights into the best possible course of action for future research. Data collected about déjà vu presents the most obvious problem because it is almost entirely based on self report, which can contain a number of biases including response bias, and social desirability bias (Brown, 2003). People also could create memories that never occurred in order to justify a respective experience of déjà vu, and whatever actual memories people do have about the experience could be muddled because the experience took place quite long ago (Thompson et al., 2004).

Furthermore, the poor research techniques used by researchers puts the generalizability of results in question. Instead of carefully ensuring that samples are representative, researchers are using easily obtained population samples. The survey designs also contain flaws because déjà vu is often put in the paranormal section which clearly implies a link to these extrasensory phenomena which may make respondents less likely to respond accurately to the survey questions (Brown, 2003).

Neurological Mechanisms

Research demonstrates that the biological components of the brain contribute to the experience of déjà vu. An important study demonstrated that the experience of déjà vu could be elicited by zapping the hippocampus and amygdala with electricity leading researchers believe that those areas of the brain correlate with déjà vu, although the exact processes involved are still unknown (Thompson et al., 2004; Brown, 2003). Minor seizures in the temporal lobes of the brain, specifically in areas corresponding to familiarity deciphering in patients without a history of epilepsy, could also cause déjà vu. Furthermore, neuronal pathways leading to other parts of the brain may become disrupted. As a result, one of the chemical chain reactions occurring across the neurons will have a dearth of neurotransmitters resulting in a delay or a quickening of that respective chemical pathway in comparison to the other chemical chain reactions occurring across the pathway. The decreased or increased rate of the reaction would be perceived as déjà vu (Brown, 2004).

Spatt (2002) theorizes that physiological differences in brain structure may contribute to the experience of déjà vu. Past research demonstrates that the mesial temporal lobe plays a significant role in episodic memory and the hippocampal gyrus plays a significant role in spatial memory. Spatt (2002) theorized that déjà vu occurs when connections between the mesiotemporal memory parts of the brain and the neocortical parts of the brain relating to environmental perception are improperly activated. The activation only occurs in the parahippocampal memory component of the brain which controls the semblance of having previously known something or someone. Meanwhile, the hippocampal system is inactive. The result of the detached occurrence of memory activation in the parahippocampal memory results in the experience of déjà vu. The inactive hippocampal system is not a deficient system, it simply did not activate, and researchers can be sure of this assertion because a hippocampal system that works well in conjunction with a prefrontal system that works well are both necessary for déjà vu to occur and then be recalled later. The inactivation of the hippocampal system in relation to the activated parahippocampal memory occurs when people make themselves more vulnerable to this phenomenon by a lack of sleep. A lack of sleep disrupts the maintenance of the memory system within the brain, which increases the likelihood that someone will experience déjà vu (Spatt, 2002).

Obviously, no data provides indisputable evidence for the theory proposed by Spatt (2002); however, evidence from experiments does provide support for certain tenants of the theory. Researchers found that electrophysiological information showed credible support for the assertion that mesiotemporal parts of the brain play a significant role in epileptic déjà vu. Furthermore, in another experiment researchers found that 4 out of 6 patients demonstrated ictal activity (déjà vu is an ictal event) in the parahippocampal gyrus while only 2 out of 10 patients from another sample that contained different symptoms such as hallucinations or feelings of peculiarity (Spatt, 2002).

Dual Processing Theories

Proponents of the different dual processing theories claim that the brain may function in one of several ways. One theory incorporated a metaphor involving a tape recorder to describe how the déjà vu phenomenon takes place in the brain. According to this theory, two parts of the brain work together in order to successfully coordinate the functions of memory. One part of the memory turns the perceptual information into storage data in the same way a tape recorder stores sounds of the voice for playback. The second part of the memory brings back the stored information in the form of memories in the same way a tape recorder would play back a previous recording. Under unusual circumstances, both mechanisms work at the same time in the brain resulting in the experience of déjà vu (Brown, 2003; Sno & Linszen, 1990). Other researchers propose a neuronal delay theory. When neuronal messages sent along pathways along the brain do no end up in the same location on the cortical centers, then the human brain interprets the signals as repeated experiences, déjà vu (O’Connor, 2006)

The neuronal message theory assumes that individuals perceiving a stimulus require an optic nerve; researchers, however, falsified that assumption. O’Connor & Moulin conducted a case study on a 25 year old blind male individual and found that the man experienced the defining criteria of déjà vu. The results indicate that other senses contribute to the déjà vu experience. More research will be necessary to determine the frequency and other defining features of déjà vu in blind individuals for comparison purposes with the sighted population (O’Connor et al., 2006).

Psychoanalytic Theory

Proponents of psychoanalytic theory focused on how déjà vu could be used as a defense mechanism, and researchers provide differing explanations for this mechanism (Findler, 1998). Freud argued that déjà vu represents an unconscious desire in the past that conflicts with a current experience it resembles. Since the desire was unconscious, it can never be recalled, so the individual experiences the disconnected feeling of déjà vu. The process works acts a defense mechanism by unconsciously driving the individual to fulfill the past desire being experienced in the present moment. Déjà vu also serves as a defense mechanism by providing psychological support to the individual experiencing the phenomenon. The person feels a sense of having experienced the same event before; as a result, the person should not feel a sense of alarm when having to cope with the current situation. Similar to Freud’s view, researchers advocating yet another perspective argue that déjà vu constitutes an unconscious desire to redo a certain life event, so the new form of action works better with the original wish. This perspective is sometimes described as encore vu (Sno & Linszen, 1990).

Memory Theories

One theory proposed by researchers proposes that perceptual information gets stored in the brain as holograms. Holograms are three dimensional images represented on the brain as distinct wave form patterns that fire across the neurons. The experience of déjà vu takes place when someone unconsciously perceives the holographic data, but cannot consciously recollect it. A déjà vu could also result when certain elements of a holographic image are observed as being akin to a previously observed image, but the previously observed image cannot be remembered (Sno & Linszen, 1990; Brown, 2003).

In addition to the holographic theory of memory, researchers also proposed more fundamental theories about memory. The first explanatory theory, Gestalt familiarity, occurs when an individual sees a perceptual layout that is similar to the overall perceptual layout of a past scene in a previous experience. The resulting familiarity with the scene that the individual has never before experienced constitutes the déjà vu phenomenon. Another theory states that when an individual experiences an emotional response that resembles one previously experienced, déjà vu can occur by working in a similar fashion. Experimental evidence supports the emotional response theory. Researchers in a study showed images to participants, and the images could only be unconsciously perceived. When researchers later asked participants which image they liked better, participants consistently chose images that had unconsciously been exposed to them. The final explanatory memory theory involves the contextual component parts of the perceived stimulus. The research highlighted the role of unconscious memory in human thought processes leading researchers to speculate that if one component part of the perceived stimulus resembles some past memory, then déjà vu may take place (Brown, 2003).

Attentional Theories

Déjà vu can also result when an individual alternates focus (attention) between different objects, people, or situations. The result of someone switching areas of focus occasionally results in the apparent reprocessing of information resulting in the experience of déjà vu. According to the theory, an individual will process a scene focusing on certain elements while disregarding others, although the disregarded portion of the data is still unconsciously interpreted by the brain. For whatever reason, some element of the scene causes a person to divert attention to a new phenomenon, which the brain previously processed as background information. The new area of already processed information is then focused on with the fovea and other perceptual tools, so déjà vu ensues as a result of the conflicting processed and seemingly reprocessed information. Researchers conducted more studies by exposing participants to words unconsciously and then later exposing them to the words again, and then the researchers compared those responses to the respective words with words that participants received only once. The results of the experiment supported that unconscious processing has an effect on behaviors and on déjà vu. However, more research is needed to clarify the exact nature of the connection between unconscious processing and déjà vu (Brown, 2003; Brown; 2004).

Discussing the theories concerning neurological mechanisms, dual processing, psychoanalytic perspectives, memory systems, and attentional shifts allows a greater understanding of déjà vu. In comparison to other psychological phenomena, déjà vu has received relatively little attention involving careful systematic research. Etiological discussion, hopefully, will inspire more creative and diligent research of this phenomenon.

References

Brown, A. S. (2003). A Review of the Déjà Vu Experience. Psychological Bulletin, 129, 394-413.

Brown, A. S. (2004). The Déjà vu Illusion. American Psychological Society, 13, 256-259

Findler, N. V. (1998). A Model-Based Theory for Déjà Vu and Related Psychological Phenomena. Computers in Human Behavior, 14, 287-301.

O’Connor, A. R., & Moulin, C. J. A. (2006). Normal patterns of deja experience in a healthy, blind male: Challenging optical pathway delay theory. Brain and Cognition, 62, 246-249.

Sno, H. S., & Linszen, D. H. (1990). The Déjà Vu Experience: Remembrance of Things Past?. The American Journal of Psychiatry, 147, 1587-1595.

Spatt, J. (2002). Déjà Vu: Possible Parahippocampal Mechanisms. The Journal of Neuropsychiatry and Clinical Neurosciences, 14, 6-9.

Thompson, R. G., Moulin, C. J. A., Conway, M. A., & Jones, R. W. (2004). Persisent Déjà vu: A disorder of memory. International Journal of Geriatric Psychiatry, 19, 906-907.