In Search of Time

via Wired: Wired Science by Jonah
Lehrer on 8/30/10

Ever since Einstein, physicists have been telling us that time – this steady
tick-tock of the universe – is much weirder than we think. It doesn’t flow in a
single, linear direction, or beat like a steady metronome. Instead, it depends
on all sorts of peculiar cosmi variables. We speed up, time slows down. (Fall
into a black hole and time turns into a viscous sludge.) And there’s nothing in the mathematical laws
of physics that says time can only go forward. In theory, at least, the hands of
your clock can tick in both directions.

But if time is so strange, then why does it seem so normal? Why
don’t we feel all the quantum weirdness? Psychologists and neuroscientists are
now beginning to explore the phenomenology of time, beginning not with spacetime
but with the fleshy brain. If our’ sense of time is largely a cognitive
illusion, then where does the illusion come from?

Let’s begin by looking at this audacious experiment, led by David Eagleman of
Baylor College of Medicine. (Eagleman is also a best-selling novelist – Sum is a brilliant riff on the
possibility of an afterlife.) He was interested in why time seems to slow down
when we’re really scared. (His research was inspired by a childhood fall.) Of
course, it’s not easy to terrify subjects in a science lab, or to trick people
into thinking that they’re about to die. (It might also violate a few IRB rules.)
And so Eagleman came up with an original experimental paradigm: SCAD jumping, which is
often described as bungee jumping without the bungee. A subject is hoisted 150
up in the air and then dropped (hopefully) onto a big net. Jad and Robert of
WNYC’s Radiolab explain
what happened next:

SCAD diving was just what David needed — it was definitely terrifying. But
he also needed a way to judge whether his subjects’ brains really did go into
turbo mode. So, he outfitted everybody with a small electronic device, called
a perceptual chronometer, which is basically a clunky wristwatch. It flashes
numbers just a little too fast to see. Under normal conditions — standing
around on the ground, say — the numbers are just a blur. But David figured, if
his subjects’ brains were in turbo mode, they would be able to read the
numbers.

The falling experience was, just as David had hoped, enough to freak out
all of his subjects. “We asked everyone how scary it was, on a scale from 1 to
10,” he reports, “and everyone said 10.” And all of the subjects reported a
slow-motion effect while falling: they consistently over-estimated the time it
took to fall. The numbers on the perceptual chronometer? They remained an
unreadable blur.

“Turns out, when you’re falling you don’t actually see in slow motion. It’s
not equivalent to the way a slow-motion camera would work,” David says. “It’s
something more interesting than that.”

According to David, it’s all about memory, not turbo perception. “Normally,
our memories are like sieves,” he says. “We’re not writing down most of what’s
passing through our system.” Think about walking down a crowded street: You
see a lot of faces, street signs, all kinds of stimuli. Most of this, though,
never becomes a part of your memory. But if a car suddenly swerves and heads
straight for you, your memory shifts gears. Now it’s writing down everything —
every cloud, every piece of dirt, every little fleeting thought, anything that
might be useful.

This is a deeply Proustian
idea. It turns out that our sense of time is deeply entangled with memory, and
that when we remember more – when we are sensitive to every madeleine
and sip of limeflower tea – we can stretch time out, like a blanket. This
suggests that the simplest way to extend our life, squeezing more experience out
of this mortal coil, is to be more attentive, more sensitive to the everyday
details of the world. The same logic should also apply to our vacations. If we
want our time off to last longer, then we should skip the beach naps and instead
cram our days full of new things, which we will notice and memorize.

Furthermore, the link between the perception of time and the density of
memory can also work in the other direction, so that it’s possible to increase
our memory by speeding up our internal clock. In 1999, a team of psychologists
at the University of Manchester demonstrated that it was possible to tweak our
“pacemaker” by exposing people to a sequence of click-trains, or acoustic tones
that arrive in rapid progression. It turns out that such click trains accelerate
our internal clock – it beats a little bit faster – which means that everything
else seems to take just a little longer. (Perhaps this is why, when companies
put us on hold, they always play sluggish muzak – the adagio sounds might slow
down our clock, thus making the frustrating experience of waiting on the phone
pass more quickly.)

A new study, by the
same Manchester lab, uses click trains to explore the implications  of this
accelerated tick-tock. It turns out that when our internal clock is ticking
faster, we don’t just perceive the external world as moving slower – we can
actually remember more about it. In other words, our sense of time isn’t just a
perceptual illusion, but instead seems to regulate the pace of information
processing in the brain. When it ticks faster, we can process more. It’s like
getting a faster set of microchips embedded in the cortex. (This suggests that
we’d get better at executing very demanding tasks, such as making quarterback
decisions in the pocket, or playing Rachmaninoff, if we listened to a series of
fast clicks first.) Here’s the abstract from the latest paper:

A series of experiments demonstrated that a 5-s train of clicks that have
been shown in previous studies to increase the subjective duration of tones
they precede (in a manner consistent with “speeding up” timing processes)
could also have an effect on information-processing rate. In general,
preceding trials by clicks made response times significantly shorter than
those for trials without clicks, but white noise had no effects on response
times. Experiments 3 and 4 investigated the effects of clicks on performance
on memory tasks, using variants of two classic experiments of cognitive
psychology: Sperling’s (1960) iconic memory task and Loftus, Johnson, and
Shimamura’s (1985) iconic masking task. In both experiments
participants were able to recall or recognize significantly more information
from stimuli preceded by clicks than those preceded by
silence.

And this returns us to the SCAD jumping paradigm used by David Eagleman.
Perhaps the feeling of terror is like a series of clicks, speeding up our clock.
We think of time as a constant, but there is nothing constant about it. Even a
fleeting feeling can change the pace of everything.

Image: A terrifying picture
of a black hole sucking in spacetime.