An Overview of Déjà Vu

Scientific findings and speculation concerning the déjà vu experience

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What am I going to talk about?

•A definition

•Facts

What is déjà vu?

•Problems in finding the causes

•Some scientific explanations

•Brain parts involved in déjà vu

What causes déjà vu?

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What is déjà vu?

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A definition

Déjà vu is that feeling when you experience something familiar, but in fact it is novel.

“We have all some experience of a feeling which comes over us occasionally, of what we

are saying or doing having been said or done before, in a remote time – of our having

been surrounded, dim ages ago, by the same faces, objects and circumstances – of our

knowing perfectly what will be said next, as if we suddenly remembered it” (Dickens 1849).

Standard definition: Any subjectively inappropriate impression of familiarity of a present

experience with an undefined past.

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Facts

Lifetime Incidence: Everybody experiences at least one déjà vu in his/her lifetime.

Not Frequent: Healthy brains do not experience it very frequent.

Decreases with Age: It starts from 8-9 and mostly happens when you are young.

Education: Happens more to better educated people.

Travel: There would be lots of new physical locations and logically, more chance of déjà vu.

Fatigue: Déjà vu experiences are more likely when fatigued.

Brain illness: Déjà vu can be associated with some brain illnesses.

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What causes déjà vu?

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Problems in finding the causes

We don’t know when déjà vu happens, it’s not frequent

Some methods are used for problematic brains, but …

Its results are not applicable to healthy brains

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Some scientific explanations

There are lots of explanations, but none is certain.

They fall into four categories:

1. Dual-processing explanations.

2. Neurological explanations.

3. Memory explanations.

4. Attentional explanations.

We will have a quick brief over them.

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Some scientific explanations

Dual Processing

Familiarity and retrieval

Encoding and retrieval

Perception and memory

Dual consciousness

Neurological

SeizureNeural

transmission delay

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Memory

Conflict in source monitoring processes

Duplication of processing

Single-element familiarity

Single-element emotional association

Gestalt familiarity

Attentional

Perceptual fluency

Inattentional blindness

Dual-Processing Explanations

This explanations assume that two cognitive processes that normally operate in synchrony become momentarily uncoordinated or out of phase.

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Novel experiencePerception

Memorizing

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1

Retrieve

Novel experiencePerception

Memorizing

1

2

Retrieve

Normal

Déjà vu

An example of dual-Processing explanations.

1 and 2 show precedence

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Neurological explanations

Suggest that déjà vu represents a brief dysfunction in the nervous system involving either a small seizure or alteration in the normal time course of neuronal transmission.

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EEG results of a patient with TLE. Déjà vu is part

of the preseizure aura in some TLEs. A logical

extension is that déjà vu in nonepileptic individuals

results from a small temporal lobe seizure

TLE = Temporal Lobe EpilepsyEEG = Electroencephalography

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Memory explanations

Memory interpretations assume that some aspect of the present setting is objectively familiar but that the source of familiarity has been forgotten.

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Attentional explanations

Attentional interpretations posit that an initial perception under distraction is followed immediately by a second perception under full attention.

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Distracted (Pay attention to the music)

Immediately after that - Paying attention to the scene

Brain parts involved in déjà vu

According to scientific explanations, many parts of the brain can be involved in this

phenomenon.

Temporal Lobe has been studied in many literature, since:

Frequent déjà vu experience with longer duration is reported in patients with Temporal Lobe

Epilepsy (TLE).

Hippocampus which plays important role in consolidating information and memorizing is in

Temporal lobe. Any malfunction of Hippocampus can have a role in experiencing déjà vu.

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Final words

Although everybody experiences déjà vu during his/her life, still there’s no dominant

explanation for this phenomenon.

Temporal lobe may be the part of the brain in which déjà vu can be triggered from.

In Week 10, Module 1 to 3, Prof. Mason talks a little about attention in “Thalamic Attention”

lecture and she talks about Temporal lobe and Hippocampus in “The Story of H.M.” and

“Memory Formation Circuitry” lectures. Her notes about “implicit Perceptual Memory” in

“Memory Types” lecture somehow can be used in attentional interpretations of déjà vu.

They all helped me understand listed explanations about déjà vu.

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References

Mainly from:

Brown, Alan S. "A review of the déjà vu experience." Psychological bulletin 129.3 (2003): 394.

Other resources:

Warren-Gash, Charlotte, and Adam Zeman. "Deja vu." Practical Neurology 3.2 (2003): 106-109.

Vlasov, P. N., A. V. Chervyakov, and V. V. Gnezditskii. "Déjà vu phenomenon-related EEG pattern. Case report." Epilepsy & Behavior Case Reports 1 (2013): 136-141.

See also:

https://www.youtube.com/watch?v=CSf8i8bHIns

https://www.youtube.com/watch?v=foVMwJtlR5s

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