Phil: Do you ever have déjà vu, Mrs. Lancaster?
Mrs. Lancaster: I don't think so, but I could check with the kitchen [1].
I hate to admit it, but I don't know anything about déjà vu. However, I believe that it is: 1) something that has happened to most of us; and 2) a completely fascinating subject in its own right. Like me, you might be wondering: What causes déjà vu?
In the movie The Matrix (1999), déjà vu was explained as, "a glitch in the matrix." In other words, "they" (i.e., the system administrators) changed something. That's all well and good for people who inhabit a computer simulation, but what about people in real life? Is there another explanation?
Philip K. Dick's Electric Dreams: Season 1, Episode 1 "Real Life"
There's an alternative explanation that that recently came up in a sci-fi television show, but sounded like it was based in sci-nonfi(ction). According to the first episode of Electric Dreams ("Real Life"), déjà vu is result of two normal cognitive functions: perception and memory [2]. In this episode, George, the main character, owns a company that produces virtual reality (VR) headsets. Unfortunately, he hit his head extremely hard. To deal with his current situation, he does two things. He uses a VR prototype to help him process what happened. In an unusually gripping VR experience, he is left wondering what is real and what is virtual. In addition to treating himself with technology, he contacts his personal doctor, Paula. Here is their dialog:
Paula: There's a theory that what we call déjà vu is actually a delay in real-time information being transmitted from one hemisphere of the brain to the other. That lag is only microseconds, but when it's received in the second hemisphere, it creates a small, momentary dissonance in perception. Now, that dissonance is misinterpreted by the cerebral cortex as memory, so the mind believes that normal events have been experienced twice.
George: Yeah, but this isn't déjà vu. It's like the memories have been there all along.
Paula: Well, they are memories, but they're memories of simulated events, events from your VR program. I think your brain's having trouble processing these simulated events, and it's creating a dissonance in your cerebral cortex, just like déjà vu.
George: I tell you it feels much more real than that. I keep having these flashes of that life, and I swear, it feels right. Feels true.
According to Paula, déjà vu is a result of delayed signals traversing the corpus callosum, which is a thick band of neurons that connect the left and right hemispheres [3]. I know the show is fiction, but how good is its explanation for déjà vu?
To evaluate Paula's theory, I consulted two resources. The first, Psychology Today, is a publication geared toward non-specialists, while the second, Neuron, publishes cutting-edge neuro-scientific research. Psychology Today returned 275 hits when I searched for "déjà vu" (mostly in the form of blog entries), and Neuron had exactly three articles with those search terms. These results tell me that this is an extremely popular topic without many studies devoted to uncovering the neuroscientific underpinnings of the phenomenon. Despite that fact, I found a small amount of evidence for the idea that there are brain systems that are out of sync [4]. For example, one study claimed that individuals who suffer from "complex partial seizures" experience hallucinations and déjà vu. They hypothesize that seizures disrupt memory and perceptual neural networks by causing them to be temporarily unsynchronized [5].
In addition to the asynchrony explanation, there is another piece that seems to fit with current findings in cognitive psychology. George reports that his experiences are authentic and feel "real" and "true." I find that interesting given the research on source monitoring. In a previous post, we discussed how people can convince themselves that they were the source of an idea, only to find out later that they picked up the idea from someone else.
Maybe there's something to the déjà vu theory put forth in Electric Dreams. But anyway you slice it, be sure you don't jeopardize recovering from a concussion with too much VR. Otherwise, you'll be staying at Mrs. Lancaster's Bed & Breakfast for a very...long...time.
Share and Enjoy!
Dr. Bob
More Material
[1] Dialog from the movie Groundhog Day (1993). The main character wakes up and experiences the exact same morning routine as the day before.
[2] Special thanks to Springfield! Springfield! for the transcript of "Real Life". Watch Electric Dreams on Amazon Prime.
[3] If you want to read about some really freaky stuff, checkout what happens when patients have their corpus callosum severed, effectively creating individuals with two separate brains.
[4] Uhlhaas, P. J., & Singer, W. (2006). Neural synchrony in brain disorders: relevance for cognitive dysfunctions and pathophysiology. Neuron, 52(1), 155-168.
[5] Medvedev, A. V. (2002). Epileptiform spikes desynchronize and diminish fast (gamma) activity of the brain: an “anti-binding” mechanism? Brain Research Bulletin, 58(1), 115-128.
Learning By Doing
To get post started, let's memorize a bunch of useless stuff. Do your best to memorize the following list:
banana
orange
kiwi
strawberry
peach
blueberry
mango
watermelon
lemon
grapefruit
What did you notice about the list? Did you reorganize the list to make the items easier to remember? Did you use any other memorization strategy?
"I have memories, but I can't tell if they're real." -K, Blade Runner 2049
In previous posts, we addressed the misconception that "memory is like a video recording." Instead, memories are reconstructed at the moment of recollection, and they are influenced by the way in which the memory is probed (e.g., "About how fast were the cars going when they hit [vs. smashed into] each other?"). Memories are also colored by one's emotional experience [1]. In recalling past events, the mind may put a positive spin on something that was horrific at the time the memory was created. A group of veterans, playing cards at the local VFW, fondly reminiscing of their time at war is a vivid example.
Pop Quiz! Without looking at the top of this post, rate how confident you are that the following words appeared in the original list [2].
| Item |
High |
Med. High |
Medium |
Med. Low |
Low |
| Kiwi |
5 |
4 |
5 |
2 |
1 |
| Strawberry |
5 |
4 |
5 |
2 |
1 |
| Apple |
5 |
4 |
5 |
2 |
1 |
| Banana |
5 |
4 |
5 |
2 |
1 |
Were you right? Some people mentally insert the word apple into the list because it is a highly iconic member of the category fruit. Activation of the category spreads to tightly knit members; thus, we infer that apple was on the list. This is may be a elementary example, but it is symptomatic of a much larger (and more interesting) issue. Memories are not indelibly stamped onto our neurons. Instead, we are prone to inserting new details at the time of retrieval.
Memory Insertion & False Memories
A much more serious example can be found in a line of research where scientists actually implanted false memories in children [3]. Scientists were able to implant false memories in about a quarter of their volunteers, and the false memories ranged from being lost in the mall to being attacked by a dog. The most outlandish implanted memory was convincing the participant that he or she had witnessed a demonic possession [4]!
Inferring an item on a list that wasn't originally there, or a false memory from childhood, are examples of confabulation, which is defined as a memory disturbance that is neither intentional nor created to deceive other people. The more commonplace version is usually just a harmless insertion of a memory that did not necessarily happen to that person. For example, on a work trip, I was completely convinced that it was my first overnight trip to West Virginia. I firmly believed that until one of my friends helpfully pointed out that I spent my 30th birthday in a resort in WV. He knew because he had been there with me! In my defense, the trip was a surprise by my wife, so I didn't know we were going to WV until we got there, and then I was shocked to see many of my good friends were there, too.
The S.T.E.M. Connection
The relevance of confabulation might not present a huge problem in middle- or high-school, but it may become an issue later in life. For example, the authorship of a scientific paper or assigning credit for an invention can become contentious when the parties involved selectively forget or insert false memories [5]. For example, George H. Daniels wrote a book entitled Science in American Society: A Social History (1971). A reviewer of his work pointed out that he had plagiarized entire paragraphs and other large sections without giving proper credit to the original source. Daniels was mortified, and he wrote an apology to the scientific community [6]. It is probably the case that Daniels did not intend to deceive his readers; instead, he falsely accepted these ideas as his own.
Aside from this specific (and potentially embarrassing) example, confabulation is important when thinking critically about someone's recollection of events. This is, of course, extremely important in eyewitness testimony (as we saw earlier). But it's also important to social scientists who rely on their participants' retrospective accounts of their behavior. Participants might think about what they logically should have done, instead of what they actually did. This inference can color the data that is ultimately collected.
In the end, we can all sympathize with K, the main character from the movie Blade Runner 2049 (2017), because our memories are subject to intrusions. He is rightfully skeptical of his memories because they can be difficult to verify if they are real (or not)!
Share and Enjoy!
Dr. Bob
Going Beyond the Information Given
[1] A great example of this is in the Pixar movie Inside Out (2015).
[2] Using the recognition test with confidence ratings was used in: Brewer, W. F., & Treyens, J. C. (1981). Role of schemata in memory for places. Cognitive psychology, 13(2), 207-230.
[3] Elizabeth Loftus is probably the most widely recognized name in this area. A summary of her research can be found in her Ted Talk.
[4] Mazzoni, G. A., Loftus, E. F., & Kirsch, I. (2001). Changing beliefs about implausible autobiographical events: a little plausibility goes a long way. Journal of Experimental Psychology: Applied, 7(1), 51-59.
[5] Goldberg, C. (2006) Have you ever plagiarized? If so, you're in good company. Retrieved from boston.com.
[6] Daniels, G.H. (14 Jan 1972) Acknowledgement. Science 175 (4018), 124-125.
