The world's clocks implacably mark every passing second, minute, and hour. But to humans, seconds of pain can feel like minutes, hours spent at a party can end in a blink, and a week of drudging through paperwork can vanish from the mind entirely.
The brain can stretch or compress the feeling of time for many reasons, including pleasure, pain, fear, age—and even the ongoing COVID-19 pandemic. Although the science behind this “subjective time” is not fully understood, some research suggests that an additional factor might influence the subjective length of your life: your income.
Research already suggests that, on average, wealthy people live longer, biologically. Now, emerging work hints that varied and novel experiences could create more “time codes” in the human brain as it processes memory formation. This, in turn, could mean that people who can afford to enjoy more vacations and hobbies, and who have more stimulating jobs, will recall having lived for a longer time on Earth.
“Even though time flies when you're having fun, when you remember back on it, you can remember much more of this extended experience compared to a boring experience,” says Jørgen Sugar, a postdoctoral student at the Norwegian University of Science and Technology's Kavli Institute for Systems Neuroscience. He’s part of a team of scientists investigating these mental time codes.
The idea that novelty—the newness of an experience which may stick out in a person’s memory—can affect the experience of time also seems to fit cultures that don’t measure time using clocks (many cultures rely instead on celestial, cultural, and seasonal events to mark the flow of time). “Our experience of time does vary according to circumstances, and also according to the kind of rhythm of activity we engage in,” says Chris Sinha, a cognitive scientist working with Hunan University who has studied so-called “event-based time” in Amazonian tribes and linguistic minority groups in China.
But other experts aren’t convinced. According to Monica Capra, an economist with a background in neuro-economics at Claremont Graduate University, subjective time isn’t well understood scientifically. What’s more, she says, there are too many factors to consider in how the brain processes time. For instance, according to Adrian Bejan, a professor of thermodynamics at Duke University, the novelty of fun experiences can simply wear off.
Still, researchers from across many fields are keen to unravel the mysteries of memory and subjective time. According to Sugar, understanding how humans form and retrieve memories can inform many facets of society, such as law, education, and healthcare—and perhaps can even aid our understanding of ourselves. “The human brain is the most complex biological system we know,” he says.
Hunting for time codes
The study of subjective time has a long history. According to Valtteri Arstila, a professor of philosophy at the University of Helsinki, discussing subjective time dates back to the ancient Greek philosophers. In the 1800s, the study became more established among psychologists and philosophers, says Dan Lloyd, a professor of philosophy and neuroscience at Trinity College in Hartford, Connecticut, who along with Arstila co-edited a book called Subjective Time: The Philosophy, Psychology, and Neuroscience of Temporality.
On the physiological side of things, the field got a big break in the 1950s, when a common treatment for epilepsy focused on removing parts of patients’ brains. Henry Molaison, one such patient, had large segments of his medial temporal lobe removed. This cured his epilepsy, but left him unable to form new long-term memories. This effect suggested that the medial temporal lobe is tied to memory formation and time perception.
Sugar’s team believes that they have found a sequence of neurons that activates when the brain creates memories. The team began by studying rats, hooking bundles of electrodes to their brains and designing experiments to trigger memory formation. The first test saw the researchers transfer the rats from a box where they could move freely to a “rest box” where they mostly stayed still. The rats were moved back and forth, and the researchers hoped they would begin to use their memory to anticipate the change. In the second test, individual rats ran around a figure-eight maze. When the rats ran through the right sequence of turns, they got a cookie as a reward.
While studying the results, the researchers noticed the neurons in a part of the brain called the lateral entorhinal cortex, which is part of the medial temporal lobe, never activated the same way twice. By contrast, the neurons in the neighboring medial entorhinal cortex—which the team’s leaders previously studied in relation to space—fired predictably. This pattern would make sense, because while one can go to the same place several times, actual points in time never repeat, Sugar says. (Also find out how researchers have managed to remove and alter memories in mice.)
Activity in this brain region also varied depending on what the rats did. When they ran free, new time codes popped up faster than when they were at rest or had run through the maze for the umpteenth time. According to Sugar, the brain doesn’t want to waste time memorizing moments that are dull or non-essential. So, it seems the rats created more memories when their actions were free, engaging, or varied.
Extrapolating the findings to humans, it’s possible that someone with more money may be able to purchase more new experiences, sparking more time codes—though Sugar notes that people don’t need massive pay checks to lead dynamic and interesting lives.
There’s also a difference between short-term, “working” memory felt in the moment and long-term, episodic memory viewed in retrospect, Sugar says. For example, a university student sitting through a dull lecture will feel like it takes forever to end, while time flies for the student sitting in an interesting lecture. However, when looking back on those times, the boring class that created fewer time codes will have disappeared from the mind, while the fascinating class that flew by will be full of memories and, thus, feel longer in retrospect.
Can we escape time?
According to Hunan University’s Sinha, humans tend to create internal narratives about themselves, and a life full of rich and varied stories will likely have a satisfying quality to it in retrospect compared to a life constrained by uniformity. As such, he suspects that having more control over your time—something that could be afforded by both wealth and using event-based, clock-less time—could lead to more novel memories and a more fleshed-out life story.
But even if higher-paid jobs can lead to more new experiences, wealthy people aren’t necessarily spending money that way, argues Claremont Graduate University’s Capra. A millionaire, for instance, may spend money on a fancy watch, but this isn’t likely to change their perception of time the way a vacation or even a low-cost hike would, she says.
Further, not everyone needs, or would even enjoy, pricey vacations or flashy jobs. Someone could derive enjoyment and satisfaction out of painting houses or gardening. For parents at all socio-economic levels, spending time with their kids is a way to find joy; CEOs and other money-rich, time-poor employees may miss out on this quality family time.
Age is also a well-documented and wealth-independent factor in how we experience subjective time. Last year, Duke’s Bejan penned an article explaining why time seems to speed up as people grow older. In it, the professor of thermodynamics posits that “eye jiggles” are primarily behind the phenomenon.
Human eyes perform these jiggles, more formally called “saccades,” in response to a change in the field of vision. Our eyes quickly scan the surroundings and then send the data to the brain. Youthful eyes jiggle regularly to take in new or unfamiliar stimuli. As the person attached to those eyes ages, the eye muscles grow slower and the pathways between the eye and the brain grow longer, more complex, or, in some cases, damaged.
In all, this means the brain receives less input over the course of a day. But by a certain age, the brain has grown accustomed to a certain amount of stimuli, and the relatively small amount received in old age leaves a person with the feeling that a day has ended too soon.
According to Bejan, the wealthy can't trick time into slowing down for them. For a rich person, taking a vacation to Maui may make time slow down for a while, Bejan says, but sooner or later it loses its charm, time speeds up again, and the jet-setter wants to get back to the office. “Not that you should feel sorry for the rich and famous,” he says.
According to Trinity College’s Lloyd, wealth could actually get in the way of living a subjectively longer life. A rich person may have more control over their environment, leading to fewer time-expanding surprises.
Arstila, on the other hand, says it’s possible that people with less money have fewer chances and resources to escape the dull or monotonous parts of their lives. “So I think like the main thing is that wealthy people have the option of getting rid of their daily routines,” he says, though he notes that memory is just one aspect of subjective time.
Researchers are still learning how the brain perceives time and the internal and external factors that can affect the way we experience it. Sickness, poor physical health, and malnutrition can also have a detrimental effect on memory, Sugar says. His team is in the early stages of further exploring time codes using mice, genetic modifications, and extremely small cameras. The team’s work with rats also suggests that innate biology may play a role: In their experiments to date, some subjects just naturally had a harder time memorizing things than others.
For now, the idea of subjective time is still full of many unknowns, including the impact of memory and the exact effects of wealth, if any. But for many researchers across fields, the complexities of time and the brain remain rich and interesting areas of study. “It’s a very pervasive psychological experience,” Lloyd says, “and we don’t quite know how it works.”