Smash Mouth got it right: The years start comin’ and they don’t stop comin’.
What wibbly-wobbly, timey-wimey facts has science taught us about aging and our brains?
We are all inherently aware that time is subjective.
You probably first noticed in school that one particular semester felt shorter than
the last one. You may have shaken it off as a fluke, but then, as time went on,
you began to realize that each and every school year seemed thinner than the last.
In his memoir, Summer of a Dormouse, written at the age of 75, the author John Mortimer noted:
"In childhood, the afternoons spread out for years. For the old,
the years flicker past like the briefest of afternoons. The playwright Christopher Fry,
now 93, told me that after the age of 80 you seem to be having breakfast every five minutes."
That time speeds up as we get older has been widely observed, but can science tell us why?
Some of the most common explanations are tied to memory, and, like memory,
such explanations tend to be frustratingly fuzzy. As noted by Psychology Today, one
theory holds that our perception of time's passing is inherently linked to the years we have lived.
To a 5-year-old child, a single year feels incredibly long as it represents
20% of their life so far — more if we discount their infancy, which might not be remembered.
To a person in old age, however, a year is a tiny fraction of the life they have lived.
"How old are you?"
"Seven, but I look a lot older."
This proportional explanation is somewhat satisfying, but it still
doesn't quite touch on why. Thankfully, experts in the fields of physics and
biology are increasingly trying to nail down the phenomenon in scientific terms.
Writing for Psychology Today, Dr. Clifford N. Lazarus explains a common experiment,
in which both small children and older adults are asked to estimate the passing of a single minute.
According to Lazarus, children tend to vastly overestimate the passing of time,
often guessing that a minute has passed within just 40 seconds.
In contrast, adults often perceive a minute has passed at the 70-second mark.
Scientists have postulated that this disparity of time perception may be the result of the
gradual slowing of the "neural pacemaker" of the brain. In childhood, the brain processes
a greater number of images — Lazarus makes the comparison to a film camera rolling at a higher
frame rate per second — but like the heart, the beating of which slows as we age, the process of
neurovisual memory-making becomes slower-paced, meaning that time appears to pass more quickly.
"Doctor, what's going on?"
"It's a timey wimey thing."
Lazarus points to a 2019 paper by Professor Adrian Bejan, published in the European Review, which
describes how more time passes between the arrival of each newly-created neural image. Bejan presents
a series of scientific models which suggests the difference between how we perceive time and how
much time has actually passed might be reflected in the slowing down of our neural processes,
which might explain why those long summer months seem to become shorter as the years roll on.
It may sound from the experiment that children and adults tend to misjudge the passage of time
in their own ways. And if the idea that the brain slows down isn't a particularly attractive one,
other research into human time perception suggests that our sense of time's passing
actually becomes more acute as we develop.
As noted by NBC News, neuroscientists conducted 'temporal bisection tasking,"
a basic experiment meant to measure the accuracy of time perception, which had
participants compare the length of tones they were played. Neuroscientist Patricia Costello explains:
"You first hear a short tone that's about a fraction of a second. Then
you hear comparison tones. You're supposed to respond [...] and say
if the next tone is more like the short or more like the long one."
In these experiments, it was discovered that the youngest children tested — around the age
of five — had notable discrepancies in their perception of short tones.
In particular, children in that age group tended to perceive short tones as longer than they were,
which coincides with anecdotal evidence that time seems to pass more slowly in our formative years.
Time may also seem to pass much more quickly when we are fully grown because of how differently we
spend our time as adults in comparison to when we were children. In our early years, many of our
experiences are formative and meaningful; often, we are experiencing things for the first time,
getting to understand the world around us, and learning new things all day long.
"Without time, we don't exist."
However, as Scientific American argues, the older we get, the more familiar with the world
we become. But as the surprises and spontaneity of childhood are replaced with the monotonous
chores and routines of adult life, we create fewer new memories. Can you remember what you
thought and felt while eating breakfast seven days ago? How about the last time you did the laundry?
With fewer truly unique moments each day, multiple memories tend to blur into one.