Déjà Vu | Research & Encyclopedia Articles

Déjà vu is a memory phenomenon widely experienced by the general public and is often cited in the popular literature. While the experience was described in the scientific literature as early as the mid-1800s, researchers used a variety of different terms to describe the experience (e.g., paramnesia) until the middle of the twentieth century. A standard definition of déjà vu used today was provided by Neppe (1983, p. 3): "any subjectively inappropriate impression of familiarity of a present experience with an undefined past."

Survey research indicates that between half to two-thirds of individuals have had a déjà vu experience, although this estimate varies considerably (30 to 97 percent) across three dozen investigations. Of those who experience déjà vu, nearly all have had more than one, and most experience one or more each year. A déjà vu experience is typically triggered by a visual scene, lasts for a few seconds, and is associated with mild stress, anxiety, or fatigue. The primary psychological reaction is surprise, and the time sense seems to slow down.

The incidence of déjà vu decreases systematically with age, and this is probably due to an increase in societal awareness across recent years. For example, Gallup and Newport (1991) found that belief in déjà vu nearly doubled between 1978 and 1990. There may be a decrease in reports of déjà vu with age because older adults grew up in a time when belief in déjà vu was not as widely accepted as it is today.

Déjà vu appears to be more common in better-educated and better-traveled individuals; there is no evidence of gender differences. Déjà vu also occurs in the aura preceding a seizure in some temporal lobe epileptics (TLEs). This trend motivated research to determine whether déjà vu is a potential diagnostic tool in seizure activity, epilepsy, and brain pathology. Accumulating evidence, however, does not support such speculation.

Interpretations of déjà have varied from the parapsychological (a telepathic reversion to a previous lifetime) to the psychodynamic (the mind neutralizes an emotional situation by displacing it into the past). These theses are thoroughly discussed by Sno and Linszen (1990) and Neppe (1983). We will examine several possible scientific interpretations.

For more than a century, researchers have suggested that a déjà vu experience reflects a neurological dysfunction. Since déjà vu is part of the preseizure aura in some TLEs, it seems reasonable that déjà vu in nonepileptics may result from small temporal lobe seizures. Another interpretation is that the déjà vu experience results from a momentary delay in neuronal transmission from the perceptual organ to the higher processing centers of the brain. This slight (several millisecond) increase in the normal time taken to transmit the message because of a synaptic dysfunction may lead to a misinterpretation of the information as being old.

Another neurological interpretation involves two pathways rather than one. In the visual system, information is received in the cortex first from the primary and then a secondary pathway. When the normally brief delay between the two tracks lengthens, the usually seamless integration of the two messages is disrupted and experienced as two separate messages. A variation on this position is that the primary rather than the secondary neuronal path is inordinately slowed, resulting in a reversal of the normal sequence of messages. We routinely interpret information from the primary pathway as our initial perception, so when the secondary pathway arrives slightly before the primary pathway, the information from the primary pathway feels familiar because a "memory" match already exists—it was established moments before.

It is possible that the individual experienced the present situation not directly but through a magazine, movie, TV show, or dream. Considerable research suggests that source confusions are routine and that déjà vu may reflect a match with a "memory" created by media or imagination. Another memory perspective is that the type of cognitive processing is being duplicated rather than the actual memory. Retrieval success often depends upon the correspondence between the way information is processed during input and retrieval. If the cognitive processing of new information follows a set of mental procedures similar to those of a prior experience, an unexpected sense of familiarity may result.

Another memory perspective is that one aspect of the present setting is objectively familiar, but conscious recognition fails when the object appears in a different context. The familiarity elicited by the unidentified object is then overgeneralized to the entire setting. On a visit to a friend's home for the first time, for example, the grandfather clock in the corner is identical to one in your aunt's home. The implicit familiarity of this object is not connected to the "old" object but instead misattributed to the objectively new setting.

Finally, the present setting may evoke a sense of déjà vu because of a familiar organization of the elements in a scene. It is not the grandfather clock in the living room of your friend's new home that is familiar but rather that the room's layout: a sofa to the right of the love seat, with a stairway to the left and a grandfather clock against the back wall, the same as in your aunt's house.

An ongoing perceptual experience may occasionally be divided into separate perceptions through distraction or inattention. In this explanation, first proposed by Titchener in 1924, a brief initial perception under diminished attention is followed immediately by a second perception under full attention. The second impression matches the "ignored" first glance taken moments earlier, giving rise to the feeling that the current experience duplicates something experienced before. As you walk into a new hotel lobby talking on your cell phone, you process the scene without full attention. When you hang up, you perceive the situation with full awareness and get the feeling that you have been here before. Recent research on inattentional blindness by Mack and Rock (1998) suggests that individuals often miss clearly visible objects if they are focused on something else, even when the unattended object is directly in front of them.

Routine cognitive experience may often involve the operation of two separate but interactive processes. While both processes usually operate in concert, occasionally they might shift out of synchrony, or one process might occur in the absence of the other. For example, retrieval and familiarity usually operate in an independent but coordinated manner, with recall accompanied by familiarity. When retrieval is activated without familiarity, a familiar setting seems momentarily unfamiliar (jamais vu). Conversely, when familiarity is activated in the absence of retrieval, déjà vu is the result. Another interpretation is that memory encoding and retrieval usually operate independently of each other. We experience a new situation; then we encode it into memory. However, if both encoding and retrieval are simultaneously activated, this spurious familiarity results in déjà vu.

Finally, we may have two different varieties of consciousness: One processes information from the environment, whereas the other monitors our inner, mental world. Déjà vu may occur when normal consciousness is diminished by distraction, fatigue, or seizure, forcing reliance on the internal consciousness operating from internally generated images, resulting in a misreading of a new experience as old.

In summary, déjà vu is experienced by most people on an average of once per year. Its incidence decreases with age, increases with education, and is more common under stress or fatigue. Likely explanations include neurological dysfunction (seizure, synaptic slowdown), implicit familiarity of objects, divided attention followed by full perception, and/or alteration in the normal function of two cognitive processes.

Gallup, G. H., and Newport, F. (1991). Belief in paranormal phenomena among adult Americans. The Skeptical Inquirer 15, 137-146.

Mack, A., and Rock, I. (1998). Inattentional blindness. Cambridge, MA: MIT Press.

Neppe, V. M. (1983). The psychology of déjà vu: Have I been here before? Johannesburg: Witwatersrand University Press.

Sno, H. N., and Linszen, D. H. (1990). The déjà vu experience: Remembrance of things past? American Journal of Psychiatry 147, 1,587-1,595.

Titchener, E. B. (1924). A beginner's psychology. New York: Macmillan

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