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Is this why time speeds up as we age?
We take fewer mental pictures per second.
- Recent memories run in our brains like sped-up old movies.
- In childhood, we capture images in our memory much more quickly.
- The complexities of grownup neural pathways are no match for the direct routes of young brains.
Mechanical engineer Adrian Bejan of Duke University has an interesting theory regarding the strange phenomenon by which time seems to speed up as we age. It's not the only theory, mind you, but an interesting one. In his just-published paper, "Why the Days Seem Shorter as We Get Older," he links the phenomenon to the idea that visual images and the manner in which we process them are the language in which we store and retrieve memories.
Considering it an issue of physics, he suggests that we more rapidly capture and remember visual data when we're young and that this sets our personal "mind time" playback rate. Since it takes longer to capture images and memory when we're older, for a number of reasons, the same length of clock time results in fewer images. When we play our back memories at our habitual mind-time rate, they seem sped up to us, much like how old movies appear (the reason why they appear so will be explained shortly). Hence, the clock time they encompass seems to have gone by faster than older memories.
"The human mind senses time changing when the perceived images change. Days seemed to last longer in your youth because the young mind receives more images during one day than the same mind in old age."
To understand Bejan's concept, it helps to understand the old-movie phenomenon. Obviously, the sense of motion in films is produced by rapidly flashing a sequence of changing images before our eyes that causes our brains to see a cohesive moving event. In the early days of cinema, movie cameras captured images at 16 frames per second.
Since The Jazz Singer in 1927 — in order to accommodate sound — we've filmed and played back movies at 24 frames per second. This means that when we play a second of an old 16 fps film, it goes by in just two-thirds of a second, making it seems like everyone in those days moved more quickly than we do now, or that their time was sped-up. This is the essential conceit behind Bejan's hypothesis.
In this excerpt from Peter Jackson's WWI movie "They Shall Not Grow Old," the playback speed changes from 24 fps to the original 16 fps at the same moment the black-and-white contrast is corrected, and everyone is revealed to be moving at a normal speed. Image source: Imperial War Museums
According to Bejan's paper, "Time represents perceived changes in stimuli (observed facts), such as visual images. The human mind perceives reality (nature, physics) through images that occur as visual inputs reach the cortex."
Clock time is mutually agreed-upon and measurable: All clocks agree on its passage, barring mechanical irregularities. Mind time is more subjective, though, and, "The time that you perceive is not the same as the time perceived by another." Bejan says this is caused by the way we interpret time looking back on memories recent and distant. Our playback rate is constant but fewer images are recorded in memory by older people, producing the old-movie effect.
Processing memory images more slowly as we age
The paper notes that the average adult makes three to five rapid eye movements — or "saccades" — each second, resting in intervals of 200–300 milliseconds in-between. These rest stops are called "fixations." If fixations go on for too long, the visual image blurs, its perception fades away in about 10 seconds, and it's thus less likely to be captured in memory. Because of this, and because one can rarely take in the entire field of vision without moving one's eyes, saccade reaction time is critical to gathering images to store in memory.
In infants, the fixation periods are shorter, and thus the saccades more frequent, allowing the discernment and capture of more images.
As for older people, Bejan cites a study that found "peak [saccade] velocities were significantly reduced in the elderly." In the study, the entire visual system lagged, and "saccadic accuracy was significantly decreased." There are a couple of reasons for this. First, the more complicated neural pathways that have evolved over the course of a lifetime slow down the trip from the eyes to the cortex — children's pathways are still fairly simple, making the journey much more direct and thus shorter. Second, fatigue — used here as a broad term encompassing "impairment, or loss, of efficiency and skill" — lengthens the fixations so they don't stick and reduces the frequency of saccades.
Why do you think time speeds up?
In addition to Bejan's hypothesis, one can also think of other possible reasons that time speeds up in adults as they age:
- A change from the flitting-from-object-to-object attention of childhood to the more concentrated attention required for adult tasks produces fewer visually distinct images worthy of capture.
- Adult responsibilities keep adults busier, and thus the days, weeks, and months fly by more quickly. All of us can remember being bored as children, a sensation that for most of us is a thing of the past.
- A heightening awareness of brevity of life.
It would be interesting to learn if people in retirement continue to experience the speeding up of time.
Construction of the $500 billion dollar tech city-state of the future is moving ahead.
- The futuristic megacity Neom is being built in Saudi Arabia.
- The city will be fully automated, leading in health, education and quality of life.
- It will feature an artificial moon, cloud seeding, robotic gladiators and flying taxis.
The Red Sea area where Neom will be built:
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A new study suggests that a century-old vaccine may reduce the severity of coronavirus cases.
- A new study finds a country's tuberculosis BCG vaccination is linked to its COVID-19 mortality rate.
- More BCG vaccinations is connected to fewer severe coronavirus cases.
- The study is preliminary and more research is needed to support the findings.
Professor Luis Escobar.
Credit: Virginia Tech
A study of the manner in which memory works turns up a surprising thing.
- Researchers have found that some basic words appear to be more memorable than others.
- Some faces are also easier to commit to memory.
- Scientists suggest that these words serve as semantic bridges when the brain is searching for a memory.
Cognitive psychologist Weizhen Xie (Zane) of the NIH's National Institute of Neurological Disorders and Stroke (NINDS) works with people who have intractable epilepsy, a form of the disorder that can't be controlled with medications. During research into the brain activity of patients, he and his colleagues discovered something odd about human memory: It appears that certain basic words are consistently more memorable than other basic words.
The research is published in Nature Human Behaviour.
An odd find
Image source: Tsekhmister/Shutterstock
Xie's team was re-analyzing memory tests of 30 epilepsy patients undertaken by Kareem Zaghloul of NINDS.
"Our goal is to find and eliminate the source of these harmful and debilitating seizures," Zaghloul said. "The monitoring period also provides a rare opportunity to record the neural activity that controls other parts of our lives. With the help of these patient volunteers we have been able to uncover some of the blueprints behind our memories."
Specifically, the participants were shown word pairs, such as "hand" and "apple." To better understand how the brain might remember such pairings, after a brief interval, participants were supplied one of the two words and asked to recall the other. Of the 300 words used in the tests, five of them proved to be five times more likely to be recalled: pig, tank, doll, pond, and door.
The scientists were perplexed that these words were so much more memorable than words like "cat," "street," "stair," "couch," and "cloud."
Intrigued, the researchers looked at a second data source from a word test taken by 2,623 healthy individuals via Amazon's Mechanical Turk and found essentially the same thing.
"We saw that some things — in this case, words — may be inherently easier for our brains to recall than others," Zaghloul said. That the Mechanical Turk results were so similar may "provide the strongest evidence to date that what we discovered about how the brain controls memory in this set of patients may also be true for people outside of the study."
Why understanding memory matters
Image source: Orawan Pattarawimonchai/Shutterstock
"Our memories play a fundamental role in who we are and how our brains work," Xie said. "However, one of the biggest challenges of studying memory is that people often remember the same things in different ways, making it difficult for researchers to compare people's performances on memory tests." He added that the search for some kind of unified theory of memory has been going on for over a century.
If a comprehensive understanding of the way memory works can be developed, the researchers say that "we can predict what people should remember in advance and understand how our brains do this, then we might be able to develop better ways to evaluate someone's overall brain health."
Image source: joob_in/Shutterstock
Xie's interest in this was piqued during a conversation with Wilma Bainbridge of University of Chicago at a Christmas party a couple of years ago. Bainbridge was, at the time, wrapping up a study of 1,000 volunteers that suggested certain faces are universally more memorable than others.
Bainbridge recalls, "Our exciting finding is that there are some images of people or places that are inherently memorable for all people, even though we have each seen different things in our lives. And if image memorability is so powerful, this means we can know in advance what people are likely to remember or forget."
Image source: Anatomography/Wikimedia
At first, the scientists suspected that the memorable words and faces were simply recalled more frequently and were thus easier to recall. They envisioned them as being akin to "highly trafficked spots connected to smaller spots representing the less memorable words." They developed a modeling program based on word frequencies found in books, new articles, and Wikipedia pages. Unfortunately, the model was unable to predict or duplicate the results they saw in their clinical experiments.
Eventually, the researchers came to suspect that the memorability of certain words was linked to the frequency with which the brain used them as semantic links between other memories, making them often-visited hubs in individuals's memory networks, and therefore places the brain jumped to early and often when retrieving memories. This idea was supported by observed activity in participants' anterior temporal lobe, a language center.
In epilepsy patients, these words were so frequently recalled that subjects often shouted them out even when they were incorrect responses to word-pair inquiries.
Modern search engines no longer simply look for raw words when resolving an inquiry: They also look for semantic — contextual and meaning — connections so that the results they present may better anticipate what it is you're looking for. Xie suggests something similar may be happening in the brain: "You know when you type words into a search engine, and it shows you a list of highly relevant guesses? It feels like the search engine is reading your mind. Well, our results suggest that the brains of the subjects in this study did something similar when they tried to recall a paired word, and we think that this may happen when we remember many of our past experiences."
He also notes that it may one day be possible to leverage individuals' apparently wired-in knowledge of their language as a fixed point against which to assess the health of their memory and brain.